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Structural and functional implications of phase separation of membrane protein LacY in Escherichia coli | Ncm

Structural and functional implications of phase separation of membrane protein LacY in Escherichia coli | Ncm | RMH | Scoop.it

Liquid-liquid phase-separation (LLPS) controls protein activity and dynamically organizes (macro)molecules in living systems without the need for membrane-bound compartments. Biomolecular condensates of water-soluble proteins have extensively been studied, but little is known about LLPS of membrane proteins. In this work we induce in vivo condensation of lactose permease (LacY), a widely-studied model monomeric inner membrane protein in E. coli, and evaluate how it affects LacY function. We fused LacY with engineered, condensate-forming protein PopTag. We observe major changes in the localization and mobility of LacYPop. Molecular dynamics simulations show how the PopTag domain drives the condensate-like association dynamics of LacYPop through hydrophobic sticker interactions. LacYPop preserves native-level transport activity and outperforms the non-condensed LacY under mild hyperosmotic stress (osmotic upshift). In osmotically stressed cells, membrane-bound biomolecular condensates also reduce deformation of the cytoplasmic membrane. Perturbation experiments suggest that membrane curvature drives the accumulation of LacYPop at the poles of E. coli. Co-condensation of LacY and β-galactosidase LacZ slightly reduces their activity and results in remarkable cellular reorganization of the proteins. Our research shows the localization, dynamics, and function of phase-separated membrane proteins in bacteria and highlights the potential of LLPS for engineering complex metabolic networks in vivo. Phase-separation of the transport protein LacY alters its membrane localization and mobility, preserves its transport activity, reduces cell membrane stress under osmotic upshift, and LacY forms mixed condensates with the enzyme β-galactosidase LacZ.

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PopTag is the C-terminal part of the phase separating protein PopZ

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https://www.pnas.org/doi/10.1073/pnas.2534387123

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RNAi-Based Molecular Biopesticide: Inspired by Nature, Precision by Science, and Harmony to the Ecosystem | acs

RNAi-Based Molecular Biopesticide: Inspired by Nature, Precision by Science, and Harmony to the Ecosystem | acs | RMH | Scoop.it

RNA interference (RNAi)-based molecular biopesticides represent a transformative approach to sustainable crop protection. By harnessing a natural gene silencing mechanism, these next-generation pesticides offer unparalleled species specificity, potentially overcoming the limitations of broad-spectrum chemicals. This review systematically outlines the research and development framework for RNA biopesticides. We explore the core processes of target gene discovery, RNA design with the use of computational tools, and scalable production methods. A significant focus is placed on delivery strategies, including nanocarriers and carrier-free systems. Furthermore, we critically discuss the biosafety considerations and ecological impacts of deploying RNAi agents in the environment. This review synthesizes how RNA biopesticides, inspired by nature and refined by scientific precision, can be integrated into agricultural ecosystems for harmonious and effective crop protection.

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Hyperspectral Remote Sensing for Harmful Algal Bloom Detection: Pseudo-nitzschia in the Northeast Pacific | brvm

Hyperspectral Remote Sensing for Harmful Algal Bloom Detection: Pseudo-nitzschia in the Northeast Pacific | brvm | RMH | Scoop.it

Diatoms are microscopic marine algae that are critical for global primary production, carbon sequestration, and fisheries productivity. However, select diatoms may form harmful algal blooms, which threaten marine ecosystems and the fisheries they sustain. Rapidly identifying harmful blooms is necessary to effectively manage marine resources, yet current identification methods are limited by expensive and labor-intensive in situ point sampling. Hyperspectral remote sensing enables scalable monitoring, but its ability to resolve taxonomic shifts within phytoplankton groups (e.g. diatoms) is largely unknown. To investigate this uncertainty, we cultured four dominant diatom genera from the California Current upwelling system, including this systems' most abundant harmful algae, Pseudo-nitzschia. The hyperspectral absorption and backscatter of these taxa were measured and used to model spectral reflectances that remote sensing platforms (satellites/drones) might detect. Differences between fingerprints of these taxa were quantified using vector-based and statistical analyses. Mean spectral differences of 48% were observed between the most dominant diatom, Thalassiosira, and the most toxic diatom, Pseudo-nitzschia. Differences of approximately 30% were found between Pseudo-nitzschia and the second and third most abundant diatoms, Chaetoceros and Asterionellopsis. Successful identification of Pseudo-nitzschia's reflectance fingerprint was driven by the presence of a unique feature around 560 nm. The distinct spectral fingerprint of Pseudo-nitzschia indicates that it can be distinguished from benign diatom blooms using hyperspectral remote sensing platforms.

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Unraveling posttranscriptional regulatory networks in phage infection | Tin

Unraveling posttranscriptional regulatory networks in phage infection | Tin | RMH | Scoop.it
Phages employ sophisticated transcriptional regulatory networks to optimize replication. Recently, Silverman et al. used RIL-seq (RNA interaction by ligation and sequencing) to reveal an additional layer of regulation and uncovered the Hfq-mediated posttranscriptional regulon of the model phage lambda.
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RIL-seq (RNA interaction by ligation and sequencing) provides a global overview of the Hfq-mediated RNA interactome.  Upon phage infection, the RNA chaperone Hfq mediates base pairing between phage and host RNAs, which can, for example, lead to activation (green) or repression (red) of translation. To globally analyze these interactions via RIL-seq, the RNAs are crosslinked to Hfq using UV light. Following cell lysis, RNAs bound to Hfq are trimmed and interacting RNAs are ligated to generate chimeric RNA molecules, which are finally identified via sequencing.

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Disentangling coevolutionary constraints for modeling protein conformational heterogeneity | ComB

Disentangling coevolutionary constraints for modeling protein conformational heterogeneity | ComB | RMH | Scoop.it

Accurate characterization of multi-state protein conformations is crucial for understanding their functional mechanisms and advancing targeted therapies. Extracting coevolutionary constraints from homologous sequences helps reveal protein structure and function, which can be automatically captured by MSA Transformer leveraging attention mechanisms. Making use of the multi-conformational coevolutionary signals captured by MSA Transformer, we introduce in this study EvoSplit to disentangle coevolutionary signals associated with distinct conformations to guide protein structure predictions. EvoSplit outperforms AF-Cluster on 85 fold-switching proteins and successfully models the conformations of proteins beyond AlphaFold2’s training set. We then identify 54 candidates with potential conformational diversity for cancer-related human proteins. Notably, for five GTPases, EvoSplit consistently predicts two conformations, one of which has not been previously reported. As an important example, the protein–protein interaction analysis provides new insights into novel HRAS function-associated conformations. Furthermore, the validity of these newly identified conformations is examined by evolutionary analysis and extensive molecular dynamics simulations. Understanding multi-state protein conformations is essential for elucidating their functions and developing targeted therapies. Here, the authors introduce EvoSplit, leveraging MSA Transformer to disentangle coevolutionary signals associated with distinct conformations, outperforming AF-Cluster in modeling fold-switching proteins and identifying new conformations of GTPases and HRAS.

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Raman Spectroscopy: Probing the proteome | eLife

Raman Spectroscopy: Probing the proteome | eLife | RMH | Scoop.it

Raman spectroscopy can be used to predict cellular physiology and proteome composition in E. coli.

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Schematic representation showing how Raman spectroscopy can be used to study the proteome of E. coli under different growth conditions. Light of a single wavelength (532 nanometers; top) is directed towards the E. coli (middle), and the light scattered by the various proteins in the proteome is recorded as a function of wavelength (horizontal axis, bottom). The individual proteins (represented here by different shapes and colors) all have different Raman spectra, so the overall Raman spectrum extends over a wide range of wavelengths and contains various peaks and troughs. If the growth conditions are adjusted, the composition of the proteome will also change, as will the Raman spectrum. By jointly analyzing the Raman spectra for 15 sets of growth conditions with existing data on the proteomes for these growth conditions, Kamei et al. showed that Raman data can be used to predict cellular physiology and proteome composition. In addition to proteins, other biomolecules (such as sugars) also contribute to the Raman spectra.

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PhuS conformational dynamics are essential for DNA binding and heme-responsive control of the prrF operon in Pseudomonas aeruginosa | jbc

In P. aeruginosa chronic infections heme is a primary source of the essential micronutrient iron. The cytoplasmic heme-binding protein, PhuS, regulates extracellular heme flux through its interaction with the iron-regulated heme oxygenase (HemO). Additionally, in its apo-state PhuS modulates iron homeostasis through transcriptional regulation of the prrF1,2 sRNA genes. These two functions are mutually exclusive and dependent on the conformational rearrangement of PhuS upon heme binding and coordination. Herein, we characterize a PhuS R25A variant that shows similar heme binding kinetics and transfer of heme to HemO as PhuS WT, while DNA-binding to the prrF1 promoter is completely lost, successfully uncoupling the two functions. HDX-MS analysis revealed an overall decrease in conformational dynamics of the apo- and holo-PhuS R25A compared to their WT PhuS counterparts, demonstrating the importance of conformational flexibility for DNA-binding. qRT-PCR and Northern blot analysis comparing the phuSR25A allelic mutant strain to the PAO1 WT showed a significant decrease in PrrF and PrrH levels and revealed PhuS-dependent differences in regulation over PrrF1 and PrrF2, altering the relative ratio of these two sRNAs in a heme specific manner that is distinct from iron. By removing its DNA-binding function, we elucidated the direct effects of PhuS binding on PrrF expression, separate from its effects on heme transfer and utilization. The contrasting effects on gene expression of the tandem sRNAs PrrF1 and PrrF2 in iron and heme and the resulting distinct mRNA profiles may allow the bacteria a fitness advantage in establishing chronic infection.
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Programmable spatiotemporal control of CRISPR-Cas12a: Engineering precision for next-generation gene editing and diagnostics | ssb

Programmable spatiotemporal control of CRISPR-Cas12a: Engineering precision for next-generation gene editing and diagnostics | ssb | RMH | Scoop.it
CRISPR-Cas12a has emerged as a versatile alternative to Cas9, offering distinct advantages, such as recognition of thymine-rich protospacer adjacent motifs, generation of staggered 5′ DNA breaks, simplified guide RNA architecture, and collateral (trans) single-stranded DNA cleavage. These features have enabled applications ranging from gene regulation to ultrasensitive nucleic-acid detection. However, Cas12a is typically activated immediately upon target engagement and may lack intrinsic mechanisms for restricting activity in time or space, which can increase off-target effects, systemic exposure, and loss of tissue specificity in certain contexts. Consequently, strategies that enable precise spatiotemporal control of Cas12a activity are increasingly important. Recent advances, including photocaged repeat-recognition sequence-based designs, split-crRNA architectures, chemically inducible systems, and kinetic optimization approaches, provide effective means to modulate Cas12a activation with improved precision. In diagnostic settings, temporal gating enhances signal fidelity by reducing background and false-positive readouts, while in therapeutic applications, controlled activation may enable tissue-restricted editing and safer, reversible gene regulation. This review summarizes current strategies for programmable spatiotemporal control of Cas12a, integrating mechanistic insights with emerging translational considerations, and outlines remaining challenges and opportunities for advancing safe and precise genome engineering.
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mGem: Applying microbiome therapeutic learnings to next-generation agricultural bioproducts | mBio

mGem: Applying microbiome therapeutic learnings to next-generation agricultural bioproducts | mBio | RMH | Scoop.it
Biological discoveries in plant and human systems have long advanced our understanding of how signaling, metabolism, and immunity shape cross-kingdom interactions. Building on this rich history of interdisciplinary insight, there is now a tremendous opportunity to strengthen connections between human and agricultural microbiome research. This perspective highlights key biological synergies across these systems that are essential for advancing human, agricultural, and ecosystem health. Focus is given to colonization, immune, and biosafety engineering strategies developed for microbiome therapeutics that can guide the design and development of next-generation agricultural bioproducts. Ultimately, greater knowledge exchange and collaboration across disciplines will be critical to translate microbiome discoveries into bioproducts with positive societal impact.
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In situ interrogation of microorganisms mediating hydrocarbon degradation | aem

In situ interrogation of microorganisms mediating hydrocarbon degradation | aem | RMH | Scoop.it
Microbially mediated hydrocarbon biodegradation is a cornerstone of natural attenuation and engineered bioremediation, yet the in situ mechanisms and key microbial players remain incompletely resolved due to the historical reliance on cultivation-based approaches. Recent advances in cultivation-independent tools, particularly metagenomics, stable isotope probing (SIP), and single-cell techniques, now enable more effective identification of active microbial populations, their functional genes, and metabolic networks directly mediating hydrocarbon degradation in situ. These studies have unveiled a far greater phylogenetic and functional diversity than previously recognized, including the unexpected co-existence of alkane-oxidizing archaea and bacteria in similar environments. The underlying microbial actors exploit distinctive enzymes to initialize hydrocarbon oxidation under oxic and anoxic conditions and achieve complete degradation through complex ecological networks that involve cooperative and/or competitive interactions with other community members such as viruses. These findings offer better insights into the functioning of the microorganisms that control the fate of hydrocarbons in situ and, as a final outcome, help tailor bioremediation strategies for better performance.
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Toward an integrative framework for monitoring biodegradation of environmental contaminants across scales | Cin

Toward an integrative framework for monitoring biodegradation of environmental contaminants across scales | Cin | RMH | Scoop.it
Organic contaminants from natural and anthropogenic sources threaten global water and food security. While bioremediation offers significant mitigation potential, tracking compound degradation in complex ecosystems remains challenging. Detection technologies span from microscale methods — biosensors, imaging, and volatile organic analysis — to landscape-scale remote sensing. Each technique provides unique information, but integrating these disparate data streams is a major bottleneck hindering ecological-scale tracking and assessment.  In this review, we propose a holistic monitoring framework for detecting contaminants and tracking the progress of bioremediation, highlighting minimally invasive detection techniques and cross-scale sensor integration. We discuss emerging technologies and the generation of standardized datasets essential for machine-learning applications in predicting degradation trajectories using fabricated ecosystems. Integrating environmental sensing, microbiome science, and advanced analytics provides a new chassis for interrogating remediation efforts.
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hyperspectral imaging

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Structural and functional implications of phase separation of membrane protein LacY in Escherichia coli | Ncm

Structural and functional implications of phase separation of membrane protein LacY in Escherichia coli | Ncm | RMH | Scoop.it

Liquid-liquid phase-separation (LLPS) controls protein activity and dynamically organizes (macro)molecules in living systems without the need for membrane-bound compartments. Biomolecular condensates of water-soluble proteins have extensively been studied, but little is known about LLPS of membrane proteins. In this work we induce in vivo condensation of lactose permease (LacY), a widely-studied model monomeric inner membrane protein in E. coli, and evaluate how it affects LacY function. We fused LacY with engineered, condensate-forming protein PopTag. We observe major changes in the localization and mobility of LacYPop. Molecular dynamics simulations show how the PopTag domain drives the condensate-like association dynamics of LacYPop through hydrophobic sticker interactions. LacYPop preserves native-level transport activity and outperforms the non-condensed LacY under mild hyperosmotic stress (osmotic upshift). In osmotically stressed cells, membrane-bound biomolecular condensates also reduce deformation of the cytoplasmic membrane. Perturbation experiments suggest that membrane curvature drives the accumulation of LacYPop at the poles of E. coli. Co-condensation of LacY and β-galactosidase LacZ slightly reduces their activity and results in remarkable cellular reorganization of the proteins. Our research shows the localization, dynamics, and function of phase-separated membrane proteins in bacteria and highlights the potential of LLPS for engineering complex metabolic networks in vivo. Phase-separation of the transport protein LacY alters its membrane localization and mobility, preserves its transport activity, reduces cell membrane stress under osmotic upshift, and LacY forms mixed condensates with the enzyme β-galactosidase LacZ.

mhryu@live.com's insight:

PopTag is the C-terminal part of the phase separating protein PopZ

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Target-stabilized base editors enable robust high-fidelity RNA editing | Nature Communications

Target-stabilized base editors enable robust high-fidelity RNA editing | Nature Communications | RMH | Scoop.it

RNA base editing using engineered deaminases represents a powerful tool to correct mutations at the RNA level. However, widespread off-target effects, primarily arising from dissociated free deaminases, remain a significant challenge. Here, we devise the RECODE (RNA editing with conditionally stable and enhanced ADAR1 deaminase variants) system, which employs designer degron-tagged ADAR1 deaminase (ADAR1d) with guide RNA (gRNA)-regulated stability. By promoting degradation of gRNA-unbound ADAR1d, RECODE markedly reduces transcriptome-wide edits while maintaining high on-target efficacy. Engineering gRNA for target RNA-induced conformational switching confines ADAR1d stabilization to intended editing sites, further enhancing editing precision. With structure-guided rational engineering of ADAR1d, RECODE efficiently corrects an Amyotrophic Lateral Sclerosis-relevant FUS mutation and installs a therapeutic mutation to Angptl3 in vivo, which mitigate FUS mislocalization to neuronal axons and lower plasma lipids, respectively. These findings establish RECODE as a highly stringent and efficient RNA editing technology and underscore a general principle for enhancing the specificity of RNA-guided protein effectors. Engineered RNA base editors are powerful yet limited by promiscuous deaminase activity. Here, the authors devise RECODE that enforces target-dependent deaminase stabilization, thereby reducing off-target edits, and achieving effective in vivo editing of FUS and Angptl3.

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2st, Pepper-tDeg system, an RNA aptamer-regulated protein degradation tag. tDeg serves as a C-terminal degron that renders the protein unstable unless bound to the RNA aptamer Pepper. We envisioned that fusion with tDeg promotes degradation of free deaminases, while the Pepper-bearing gRNA would stabilize these

deaminases at editing sites.

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A Toxin-Antitoxin-Driven Biosensor Platform for the Directed Evolution of d-Allulose 3-Epimerase | acs

A Toxin-Antitoxin-Driven Biosensor Platform for the Directed Evolution of d-Allulose 3-Epimerase | acs | RMH | Scoop.it

Biosensor-assisted growth-coupled screening facilitates the directed evolution of enzymes. However, antibiotic resistance-dependent screening tools generally suffer from declining selection pressure. To overcome this limitation, we developed a toxin-antitoxin-based high-throughput screening platform (TASP) for engineering d-allulose 3-epimerase (DAE), driven by a redesigned d-allulose-responsive biosensor (DB). Engineering the pPsiA promoter expanded its dynamic range to 150 mM d-allulose and enhanced signal-to-noise ratio by 14.2-fold. The TASP incorporates the toxin-antitoxin (AtaT-AtaR) as a sustainable and cell-autonomous selection pressure, where mCherry is used as a reporter gene. This design precisely links DAE catalytic activity to cell growth phenotypes, enabling both visul monitoring and quantitative analysis to rapidly identify variants. Using TASP, we identified the mutant M4–2 (W14C/G67A/L151Y/F245 K), which exhibits a 5.2-fold increase in catalytic activity and a 3.5-fold increase in half-life at 60 °C. This work establishes a reliable platform for high-throughput screening of DAE variants and advances the development of growth-coupled selection strategies.

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hts survival, 2st, the specific binding of d-allulose to PsiR induces a conformational change, resulting in its dissociation from pPsiA to activate the expression of antitoxin genes, thus neutralizing the toxin to restore the growth of the biosensor cells.

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Comparative Performance of Portable DNA Extraction Protocols and Bioinformatics Workflows for Rapid Detection of Pathogens and Antimicrobial Resistance Using Oxford Nanopore Sequencing | brvt

Comparative Performance of Portable DNA Extraction Protocols and Bioinformatics Workflows for Rapid Detection of Pathogens and Antimicrobial Resistance Using Oxford Nanopore Sequencing | brvt | RMH | Scoop.it

Oxford Nanopore technology (ONT) enables rapid, portable pathogen identification and detection of antimicrobial resistance (AMR). Still, the reliability of downstream genomic analyses is highly dependent on DNA extraction quality, particularly in resource-limited settings. This study comparatively evaluated four portable bacterial DNA extraction protocols, derived from three commercial kits, to determine their impact on nanopore sequencing performance, bioinformatics workflow completion, and field deployability. Six Gram-negative bacterial isolates (Escherichia coli, n= 4; Pseudomonas sp., n= 1; and Salmonella sp., n= 1) were processed using four extraction protocols: SwiftX DNA, SwiftX DNA with proteinase K (ProtK), SwiftX ParaBact, and NucleoSpin Microbial. Twenty-four DNA extracts (6 isolates x 4 protocols) were sequenced on a single multiplexed MinION R10.4.1 flow cell. Sequencing data were analysed using validated Galaxy-based generic and species-specific pipelines, with workflow completion defined as successful progression through quality control, assembly, virulence, plasmid and AMR detection modules. DNA purity varied substantially by extraction protocol and was strongly associated with workflow success. NucleoSpin Microbial achieved 100% workflow completion, SwiftX ParaBact achieved 83%, while both SwiftX DNA-based protocols failed to complete full workflows. Higher A260/A280 ratios were strongly correlated with successful workflow completion (Spearman’s ρ = 0.767, p < 0.0001). Importantly, key AMR genes required to classify isolates as multidrug resistant were consistently detected using both NucleoSpin Microbial and SwiftX ParaBact extractions. However, NucleoSpin Microbial assemblies showed significantly higher contiguity and enabled broader and more complete detection of virulence factors, pathogenicity islands, plasmid replicons, and accessory AMR genes, reflecting enhanced genomic resolution.

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Mining Genetically Encoded Biosensors from Filamentous Fungi | mdpi

Mining Genetically Encoded Biosensors from Filamentous Fungi | mdpi | RMH | Scoop.it
Genetically encoded biosensors represent cutting-edge biosensors due to their capabilities in real-time monitoring and precise control in living cells. However, the development of eukaryotic genetically encoded biosensors for new analytes is constrained by the shortage of signal–receptor pairs. Bacterial biosensors have been transferred to eukaryotes to expand the signal detection space, which has achieved remarkable success. However, due to the significant differences between eukaryotic and prokaryotic gene expression systems, optimizing bacterial biosensors has proven challenging. Successful cases indicate that developing orthogonal signal–receptor pairs directly from eukaryotic systems may offer a viable solution. Indeed, the potential of filamentous fungi—a highly diverse group of organisms that share conserved as well as specific signaling and metabolic pathways with yeast and mammalian cells—has been largely overlooked in biosensor development. In this review, we systematically examine biosensing systems in filamentous fungi, summarize their signal recognition receptors, signal transduction pathways, responsive transcription factors, and provide an overview of the biosensors and synthetic tools developed from them. Finally, we highlight the promise and challenges of biosensor development from filamentous fungi and discuss their potential applications.
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m-2st, inducible promoter

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Quantitative mapping of pseudouridines in bacterial RNA | Ncm

Quantitative mapping of pseudouridines in bacterial RNA | Ncm | RMH | Scoop.it

RNA pseudouridylation is one of the most prevalent post-transcriptional modifications, occurring universally across all organisms. Although pseudouridines have been extensively studied in bacterial tRNAs and rRNAs, their presence and role in bacterial mRNA remain poorly characterized. Here, we used a bisulfite-based deep sequencing approach to provide a comprehensive and quantitative measurement of bacterial pseudouridines using E. coli, to provide proof of concept. We identified 1,954 high-confidence sites in 1,331 transcripts, which is 29 times above previous estimates and representing almost 30% of the transcriptome. Furthermore, pseudouridines were significantly associated with mRNA stability and enriched in transcripts associated with secondary metabolite production and adaptation to diverse environments. Finally, we mapped pseudouridines in oral microbiome samples of human subjects, demonstrating the broad applicability of our approach in complex microbiomes. This way, we observe that, although uridines are required for modification, mRNAs from GC-rich bacteria harbored more pseudouridine sites than AT-rich genomes in our dataset. Altogether, our work highlights the advantages of mapping bacterial pseudouridines and provides a tool to study posttranscription regulation in microbial communities. Pseudouridines are RNA modifications occurring in all organisms. Here, Sharma et al. identify and quantify pseudouridines in E. coli bacteria, where this modification is associated with mRNA stability, and map pseudouridines in human oral microbiome samples.

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ptm,  BS treatment of RNA induces deletion at Ψ locations during cDNA synthesis. After sequencing, deletion sites in BS-treated samples are compared with untreated samples to accurately identify Ψ positions.

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Harnessing artificial intelligence for antimicrobial discovery and optimization | Cin

Harnessing artificial intelligence for antimicrobial discovery and optimization | Cin | RMH | Scoop.it
The rise of antimicrobial-resistant pathogens has outpaced the traditional methods of drug discovery and development, emphasizing a need for new and innovative approaches to identifying novel antibiotics. Artificial intelligence (AI) poses new opportunities to overcome the challenges in traditional drug discovery by accelerating the identification, design, and optimization of bioactive small molecules and antimicrobial peptides. AI-driven genome mining allows for the identification and prioritization of biosynthetic gene clusters, while advanced AI models facilitate molecular property prediction, predicted binding interactions, and novel structure design. This review explores the advancements that AI has enabled in antimicrobial discovery and design, as well as its current limitations.
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Bacterial iron acquisition by Escherichia coli is facilitated by amino acid complexation in a rapid-renewal environment | pnas

Bacterial iron acquisition by Escherichia coli is facilitated by amino acid complexation in a rapid-renewal environment | pnas | RMH | Scoop.it
In natural environments, bacteria often encounter low concentrations of nutrient mixtures that are continuously replenished by physical processes such as fluid flow. Studying bacterial physiology under such conditions is experimentally challenging because it is difficult to maintain steady, low nutrient concentrations with rapid renewal. Most studies on nutrient limitation have used approaches such as the chemostat, which rely on long renewal times to sustain low concentrations. We developed a Millifluidic Continuous Culture Device (MCCD), inspired by microfluidics, that enables bacterial cultivation in nutrient mixtures at low micromolar concentrations with rapid renewal driven by fluid flow. Unlike microfluidic systems, the MCCD retains sufficient culture volume to support batch-scale ‘omic analyses. Using the MCCD, we cultured E. coli in a mixture of amino acids and nucleobases at three concentration ranges spanning a fivefold difference in growth rates. Surprisingly, at the lowest concentration range, cells exhibited proteomic signatures of iron limitation despite equal total ferrous iron across conditions. Uptake experiments with labeled iron–histidine and iron–cysteine complexes confirmed that amino acids facilitated ferrous iron acquisition. Under continuous flow, siderophores were washed out, rendering this pathway ineffective and revealing a previously unrecognized mechanism of iron acquisition via soluble ferrous iron–amino acid complexes. These findings highlight the importance of studying bacterial physiology at low nutrient concentrations and also suggest a broader role for other organic substrates capable of complexing iron as potential iron sources in environments with rapid renewal.
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2st, methods,  sauer u, A peristaltic pump delivers fresh culture medium into a Sterivex filter chamber containing bacterial cells (green). A 0.45-µm pore size membrane (dotted shape) separates the inlet from the outlet. This membrane permits the passage of medium but retains cells, which are larger than the pore size and therefore remain on the membrane surface. Continuous flow ensures steady replenishment of nutrients, enabling sustained bacterial growth even at very low concentrations.

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Hyperspectral imaging | Nature Reviews Methods Primers nrmp

Hyperspectral imaging | Nature Reviews Methods Primers nrmp | RMH | Scoop.it

Hyperspectral imaging (HSI) is an advanced sensing modality that captures spatial and spectral information simultaneously, enabling non-invasive and label-free characterization of material, chemical and biological properties. This Primer overviews HSI, with an emphasis on the imaging workflow and data processing pipeline. We introduce the essential physical principles and sensor architectures, using Earth observation HSI systems as a representative example. Key steps in data acquisition, calibration and correction that determine data structure and quality are discussed. We summarize common hyperspectral data forms and highlight core analytical techniques, including dimensionality reduction, classification and spectral unmixing, together with emerging artificial intelligence-based methods that increasingly influence current HSI research. Six representative application fields are briefly surveyed to illustrate how HSI enables sub-visual feature extraction for quantitative interpretation and decision-making. We also discuss persistent challenges, including hardware trade-offs, acquisition variability and high-dimensional complexity alongside promising advances such as computational imaging, physics-guided modelling, cross-modal fusion and scalable learning frameworks. Best practices for dataset sharing, reproducibility and metadata documentation to support transparent research are included. Scalable, real-time and embedded HSI, enabled by sensor miniaturization and artificial intelligence, will push HSI into a cross-disciplinary platform for transformative scientific and societal impact. This Primer introduces hyperspectral imaging (HSI) through a concise, imaging-centric perspective, linking sensor platforms, data types and representative datasets across application domains. It highlights how platform characteristics shape data properties and downstream analysis, providing a unified reference for understanding and comparing HSI systems and data.

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Combinatorial optimization of protein systems in synthetic cells | brvsb

Combinatorial optimization of protein systems in synthetic cells | brvsb | RMH | Scoop.it

In vitro reconstitution of protein systems—e.g., metabolic pathways, genetic circuits or biosensors—often requires optimization to enhance their activity. Combinatorial DNA libraries that simultaneously target multiple genes allow for a holistic optimization strategy by studying the interplay between the systems′ components, which may reveal DNA variants that would be hidden when testing each element in isolation. Here, we screen large populations of synthetic vesicles that express combinatorial DNA variants of a DNA self-replicator or a phospholipid synthesis pathway. We simultaneously vary the strengths of multiple RBSs or synonymously mutate the first codons of multiple genes to explore the effects of the protein translation rates directly on the functionality of the two core synthetic cell modules. We isolated high performers through DNA self-selection or functional screening by fluorescence-activated cell sorting. Long-read sequencing of the fittest variants informed on the optimal RBS strengths and base substitutions in the first codons and indicated which genes were most impactful in regulating the functionality of the protein systems. Single-mutation data were used to predict the fitness of combinatorial variants, which was compared with the experimental fitness observed. The theoretical fitness of combinatorial variants was extremely predictive for the two-gene library of the DNA replicator but less for the larger pathway library. Altogether, our approach exemplifies how combinatorial testing can be expanded from single proteins to multiprotein systems, which can in the future be extended to the evolutionary engineering of even larger genetic and metabolic networks, and eventually an entire artificial cell.

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The Aspergillus nidulans transcription factor SclB governs the transition from vegetative to asexual development | mBio

The Aspergillus nidulans transcription factor SclB governs the transition from vegetative to asexual development | mBio | RMH | Scoop.it
Asexual reproduction in filamentous fungi is a common, efficient, and fast differentiation process for producing large numbers of asexual spores (conidia), which can be distributed through the air to colonize new environments. The whole process is tightly controlled by specific regulatory proteins. Among the major regulators is the zinc cluster protein of SclB (sclerotia-like B), known to influence various aspects of asexual growth and secondary metabolism in Aspergillus nidulans as well as other filamentous fungi. Two different growth conditions of A. nidulans were compared to obtain a mechanistic overview of the role of SclB, mainly during the transition of the fungus from vegetative to asexual growth. Chromatin immunoprecipitation (IP) was coupled with next-generation sequencing (ChIP-seq) and combined with transcriptomic analyses (RNA-seq). SclB coordinates this developmental shift mainly by controlling the expression of genes encoding a few, however, prominent regulators of conidiation. These include the transcription factors BrlA, VelB, and SclB and the pheromone oxygenase PpoC. Association of SclB to promoter regions requires the newly identified putative SclB response element with a nine-base-pair DNA motif. Scl2 is the corresponding protein in the fungal plant pathogen Verticillium dahliae and partially complements the A. nidulans ΔsclB asexual deficiency. This supports a partial functional complementation of this regulator among different fungal species. In summary, SclB coordinates the transition from vegetative growth to asexual reproduction in A. nidulans through in vivo transcriptional control over genes coding for established players of conidia formation.
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CBASS limits bacteriophage production while maintaining cell viability in Pseudomonas aeruginosa | brveco

CBASS limits bacteriophage production while maintaining cell viability in Pseudomonas aeruginosa | brveco | RMH | Scoop.it

CBASS is an immune pathway that recognizes phage infection and generates cyclic nucleotide signals, which directly activate effectors that stop phage replication. Membrane-acting effectors are proposed to induce cell death to prevent phage replication; however, this mechanism has not been assessed with endogenous expression levels of the effector. We therefore sought to determine the cell viability outcomes of the CBASS phospholipase effector (CapV) upon activation with 3',3'-cGAMP signals in Pseudomonas aeruginosa. Here, we surprisingly observe that constitutive 3',3'-cGAMP signaling from the synthase (CdnA) enables robust cell growth and viability while effectively abolishing phage production in a CapV-dependent manner. Exogenous 3',3'-cGAMP also enhances CBASS antiphage activity and cell growth. Moreover, constitutive activation of the CapV effector induces no cell fitness cost, and blocks replication of many, but not all, phages. This demonstrates that a cyclic nucleotide-activated CBASS effector possess a degree of phage specificity that has been previously overlooked. When CBASS is active, phage transcription and initiation of DNA replication proceed normally, but phages do not reach maximum DNA levels and fewer mature virions are produced. Based on these findings, we propose that CapV interferes with the early stages of phage capsid assembly at the cell membrane and resultantly disrupts DNA packaging. Collectively, we demonstrate that a successful CBASS response antagonizes a late-stage of the phage replication cycle while maintaining cell viability.

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Metabolic engineering of microorganisms for the valorization of C2 feedstocks | Cin

Metabolic engineering of microorganisms for the valorization of C2 feedstocks | Cin | RMH | Scoop.it
This review summarizes recent advances in the metabolic engineering of microorganisms for the valorization of C2 feedstocks into high-value chemicals and materials. We first discuss native and engineered C2 assimilation pathways, including reverse β-oxidation, aldol-condensation-based carbon extension, and thiamine pyrophosphate-dependent modules, highlighting representative strain designs in E. coli, Pseudomonas spp., and photosynthetic hosts. We then examine C1-to-C2 platform strategies that couple acetogens or gas-fermenting microbes with C2-assimilating production strains. Finally, we outline the rapidly growing toolbox of non-natural and computationally designed pathways that rewire carbon flux with minimal loss. Particular emphasis is placed on the integration of synthetic biology, enzyme engineering, genome-scale metabolic models, and artificial intelligence-driven design for building next-generation, electrified, and digitally guided C2 biorefineries. These advances are positioning C2-based biomanufacturing as a key pillar of low-carbon chemical production.
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Can nanozymes achieve more than enzymes? | Nrm

Can nanozymes achieve more than enzymes? | Nrm | RMH | Scoop.it

Nano-zymes have progressed from simple enzyme mimics to a versatile class of artificial catalysts that expand functionality beyond the reach of natural enzymes. In this Perspective, we examine how the materials design of nanozymes enables catalytic behaviors that are inaccessible to biological systems, including activity in non-biological environments, promotion of non-natural reactions and the integration of multiple catalytic functions within a single nanostructure. Through nanoscale control over physicochemical parameters and emulation of key enzyme architectures, nanozymes can achieve finely tunable activity and selectivity. Facile surface functionalization and inherent electrical connectivity further enhance their performance in complex systems. Collectively, these attributes extend catalysis beyond the constraints of natural enzymes, driving innovations in an array of different fields, including biomedicine, agriculture, environmental remediation and energy conversion. Nanocatalyst ‘nanozymes’ provide a versatile alternative to natural enzymes. Nanozymes can operate in conditions inimical to enzymes and can catalyse reactions that their natural analogues cannot. This Perspective discusses design principles, strengths, challenges and applications of nanozymes.

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