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Structural basis of directionality control in large serine integrases | mcell

Structural basis of directionality control in large serine integrases | mcell | RMH | Scoop.it
Large serine integrases catalyze unidirectional insertion of large DNA payloads and, in the presence of a cognate recombination directionality factor (RDF), catalyze unidirectional excision. Understanding how directionality is enforced has been hampered by a lack of structural information. Here, we report 8 structures of SPβ integrase-DNA complexes along the integrative (−RDF) and excisive (+RDF) reaction pathways at resolutions extending to 3.15 Å. These include tetrameric intermediates before and after strand exchange and product-bound dimers for both pathways. We find that recombination-induced conformational changes and RDF-mediated repositioning of the integrase’s coiled-coil subdomain (1) dictate which pairs of DNA sites can be assembled into active synaptic complexes and (2) dictate which product complexes will be conformationally locked, preventing back reactions. Critically, we find that the synaptic complex in which excision occurs is fundamentally different from that in which integration occurs. These insights provide a framework for engineering improved genome editing tools.
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Soil viruses as key regulators of the microbial carbon pump in deep soils | Nee

Soil viruses as key regulators of the microbial carbon pump in deep soils | Nee | RMH | Scoop.it

Deep soils store over half of terrestrial organic carbon, yet the viral mechanisms governing carbon persistence in subsurface contexts remain unclear. Here, by conducting a soil profile survey (0–700 cm) across four agroecosystems and a global synthesis of subsurface metagenomes, we established the Deep Soil Viral Resources Database, comprising 50,949 viral operational taxonomic units and 3,902 auxiliary metabolic genes (AMGs). Viral richness increased significantly with depth, accompanied by a shift towards lysogeny driven by declining carbon availability. The deep-soil virome carried AMGs and lysozymes involved in polymer degradation and cell endolysis. Viral endolysin significantly promoted necromass carbon accumulation, which contributed to increases in mineral-associated organic carbon. A synthesis of 138 global soil profiles further revealed a positive effect of viral abundance on soil organic carbon. Our findings establish a framework where viruses strengthen the microbial carbon pump in deep soils by facilitating host carbon scavenging via AMGs and promoting necromass formation via endolysin activity. Combining a metagenomic analysis of agroecosystem soils along a 7-metre depth profile with microcosm incubations and a global synthesis, the authors find increases in viral diversity, lysogeny and necromass carbon accumulation in deeper soils.

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Hidden carbon: uncovering the diversity and function of polyhydroxyalkanoates | tin

Hidden carbon: uncovering the diversity and function of polyhydroxyalkanoates | tin | RMH | Scoop.it
Polyhydroxyalkanoates (PHAs) are a widespread family of microbial carbon-storage polymers. Ecological studies often focus on polyhydroxybutyrate (PHB), obscuring the broader chemical diversity. We argue that PHA monomer composition should be treated as a microbial trait and propose a multiscale framework, from the single cell to the ecosystem level, to reveal hidden carbon dynamics.
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Induction Temperature and Feeding Profile Shape the Partitioning Between Soluble Product and Inclusion Body Formation in Escherichia coli | bab

Inclusion body (IB) processes yielding the recombinant product only as IBs are long-established in the biopharmaceutical industry. Yet, for recombinant proteins that accumulate both IBs and soluble fraction depending on the selected upstream processing (USP) strategy, the influence of process parameters on the partitioning between both forms remains poorly characterized. In this study l-lactate dehydrogenase (LDH) was selected as a model protein as it yields IBs and soluble protein concurrently. We investigated how induction temperature and specific substrate uptake rate shift the relative amount of soluble product. A response surface model revealed a sharp switch between exclusively soluble production at 25°C, exclusive IB formation at 35°C and a mixed production regime at 30°C. Further, we investigated whether these trends hold for the structurally related proteins xylose isomerase (Xiso) and pyranose-2-oxidase (P2O) using a reduced diagonal design and a projection into the LDH latent space by principal component analysis (PCA). Results revealed that the shared structural features were not sufficient to predict the expression form. Still, the LDH model served as a reference framework for identifying the extent to which other mixed producers follow established process-response trends.

mhryu@live.com's insight:

overexpression, solubility

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Programmable design of functional proteins from natural language | nat

Programmable design of functional proteins from natural language | nat | RMH | Scoop.it

Programming biological function—designing bespoke proteins to perform specified molecular tasks—is a foundational goal of molecular engineering. However, current design models remain fundamentally limited: they typically require either natural proteins as starting points for optimization or manual reformulation of functional goals as geometric and sequence-level constraints to guide candidate generation. Here we introduce Pinal, a 16-billion-parameter foundation model that designs candidate proteins from natural-language descriptions of desired function. Trained on 1.7 billion synthetically annotated protein–text pairs, Pinal links functional intent to protein sequence and structure. In computational evaluations, generated candidates combined high predicted foldability with functional-description alignment and sequence diversity, providing a basis for prioritizing experimentally testable designs. We applied Pinal to four distinct design tasks—a fluorescent protein, a polyethylene terephthalate hydrolase, an alcohol dehydrogenase and a metabolic H-protein—and experimentally observed the intended function in each case, including catalytic activity for both designed enzymes. Without iterative experimental optimization, a Pinal-designed H-protein increased product titre by 1.7-fold relative to the corresponding native Escherichia coli H-protein in a multi-enzyme CO2 fixation pathway. These findings support natural language as a high-level interface for candidate generation in protein design, enabling programmable exploration with reduced reliance on manually specified structural or sequence constraints. Pinal, a 16-billion-parameter artificial intelligence model, designs functional proteins from natural-language descriptions, demonstrating experimentally validated activities and improved CO2-fixation product yields without iterative optimization.

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http://www.denovo-pinal.com/ 

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TargetMITO: a rule-based model for generating functional synthetic mitochondrial targeting sequences in yeast | nar

TargetMITO: a rule-based model for generating functional synthetic mitochondrial targeting sequences in yeast | nar | RMH | Scoop.it

Mitochondria are essential organelles containing their own genomes, encoding a few proteins essential for energy production. Most of the mitochondrial proteins are nucleus-encoded, translated as precursors in the cytosol, with a large fraction of these precursors properly addressed by an N-terminal mitochondrial targeting sequence (MTS). These MTS share common features but no consensus sequence can explain their functionality nor the precursors-specific determinants of mitochondrial import. To help understand this mechanism, we created a simple computational model to generate functional synthetic MTS while maintaining a tight control on the design parameters. Using the budding yeast, we demonstrated the presence of precursors-specific import capabilities in addressing artificially nucleus-relocated OXPHOS proteins. Our research confirms the existence of cargo-dependent functional compatibilities and takes us one step closer towards improving gene therapy-based treatment of mitochondrial diseases.

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In vivo Gene Writing with engineered retrotransposons | CEL

In vivo Gene Writing with engineered retrotransposons | CEL | RMH | Scoop.it
Efficient integration of gene-length cargos in vivo remains challenging. Non-long terminal repeat (non-LTR) retrotransposons, which naturally mobilize large DNA segments through an RNA intermediate, could potentially address these limitations. Here, we developed a computational pipeline to systematically identify a diverse set of non-LTR retrotransposons. Extensive engineering generated elements capable of the efficient and stable insertion of reporter genes in human cells using RNA templates introduced in trans, which we term Gene Writers. Gene Writers successfully generated CD19 and CD20 chimeric antigen receptor T (CAR-T) cells ex vivo with robust antitumor activity. Lipid nanoparticle-mediated RNA delivery enabled in vivo CAR-T cell generation and stable B cell depletion in a humanized mouse model. Our study delineates a comprehensive framework for the discovery, engineering, and application of non-LTR retrotransposons and demonstrates their utility for gene-sized cargo delivery in vivo, thereby bridging a critical gap in existing gene therapy modalities.
mhryu@live.com's insight:

memory, record, integration sites were random across the genome

mined 406 candidate LTR elements from eukaryotic genomes, found a handful that work in human cells
deliver two RNAs: One is the driver messenger RNA, which the cell translates into the retrotransposase protein in lipid nanoparticles. The other is the template RNA, which carries GOI between the matching end regions.

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Bacteroides fragilis outer membrane vesicle mediates Pseudomonadota colonization by inducing autophagy on the skin | iSci

Bacteroides fragilis outer membrane vesicle mediates Pseudomonadota colonization by inducing autophagy on the skin | iSci | RMH | Scoop.it
Skin homeostasis is essential for host defense. Though constantly exposed to the external environment, signals from anaerobes have been detected in deeper skin layers, with their functional role in cutaneous immunity remaining unclear. Here, we explored whether skin-associated Bacteroidota contribute to pathogen exclusion via host autophagy. Comparative analysis of the skin microbiota revealed a progressive reduction in Pseudomonadota abundance alongside an increase in Bacteroidota during childhood-to-adulthood transition. A significant inverse correlation between Bacteroidota and Pseudomonadota abundance was observed in pediatric cohorts. Bacteroides fragilis and its secreted outer membrane vesicles (OMVs) induced autophagy, which facilitated Pseudomonadota clearance in macrophages. In vivo colonization experiments showed that live B. fragilis bacteria or intact OMVs outcompeted Pseudomonadota in wild-type mice, but not in lc3a−/− mice. These findings provide a plausible model explaining the inverse association detected in human cohorts, indicating that B. fragilis may help suppress potentially pathogenic taxa like Pseudomonadota on the skin.
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Preferred evolutionary routes of convergence in Klebsiella pneumoniae favor siderophore acquisition over hypervirulence | ncm

Preferred evolutionary routes of convergence in Klebsiella pneumoniae favor siderophore acquisition over hypervirulence | ncm | RMH | Scoop.it

The rise of Klebsiella pneumoniae combining antimicrobial resistance and virulence genes poses a major health threat, but the evolutionary routes and phenotypic consequences of this convergence are poorly understood. Here, phylogenetics of 1468 isolates and population analysis of 7520 plasmids, from >50 countries through the last two decades, reveal that convergence follows preferred, constrained evolutionary paths. The dominant route involves multidrug-resistant classical K. pneumoniae acquiring conjugative IncFIB(Mar)/IncHI1B(Mar) plasmids carrying an incomplete set of virulence biomarkers. Across 25 independent convergence events, the acquisition of the aerobactin siderophore locus was the only universal feature. These convergent isolates exhibit enhanced siderophore production but consistently lack the hypervirulent phenotype in vivo. In contrast, genuine hypervirulent strains that gain resistance remain rare. We conclude that enhanced siderophore production, not hypervirulence, is the primary adaptive trait driving the success of globally emerging convergent lineages, representing a distinct evolutionary state optimized for transmission rather than systemic invasion. Authors present a global study revealing that drug-resistant Klebsiella pneumoniae repeatedly acquires conjugative plasmids with aerobactin, boosting iron-scavenging ability without becoming hypervirulent. This may help emerging strains spread in healthcare settings.

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Drift, selection and recombination bias drive the evolution of a non-ribosomal peptide | Nee

Drift, selection and recombination bias drive the evolution of a non-ribosomal peptide | Nee | RMH | Scoop.it

Non-ribosomal peptides play important roles in microbial ecology and medicine, for example as toxins and antibiotics such as penicillin. Like ordinary proteins, non-ribosomal peptides are subject to evolutionary change, which is driven by rampant recombinations of their synthetases. The evolutionary dynamics and causes of non-ribosomal peptide diversification are not well understood, because recombinations complicate phylogenetic analysis and statistical tests for natural selection and drift. Here we study the non-ribosomal GameXPeptides, which entomopathogenic bacteria use to kill their insect prey. We use recombination-aware phylogenetics, ancestral sequence reconstruction and statistical analysis of historical recombination patterns to retrace the evolution of GameXPeptides. This uncovers dozens of new GameXPeptides, including striking patterns of structural convergence. We provide statistical and experimental evidence that this diversity is shaped by selection, but also that GameXPeptides experience substantial genetic drift and biased recombination rates that limit the space of accessible peptide variants. Our work illuminates the complex interplay of adaptive and non-adaptive evolutionary forces acting on some of the most versatile chemical weapons in nature. The structural diversity of non-ribosomal peptides is largely determined by recombination. This study shows that selection, genetic drift and biased recombination rates contribute to the diversity of GameXPeptides, non-ribosomal peptides used by entomopathogenic bacteria to kill their insect prey.

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Engineered human Argonaute 2 for targeted C-to-U RNA base editing | Nbt

Engineered human Argonaute 2 for targeted C-to-U RNA base editing | Nbt | RMH | Scoop.it

Tools for manipulating RNA that rely on nonhuman proteins, such as ISC-based and Cas-based scaffolds, can lead to unintended and little-understood effects on human cells and present challenges in therapeutic translation. Replacing them with human proteins engineered for expanded, programmable functions could bypass the limitations of these foreign proteins. Here we demonstrate that human Argonaute 2 (AGO2) can be repurposed as a modular RNA targeting domain. AGO2 fused to a C-to-U deaminase enables AGO-led targeted editing of RNA (ALTER). Using guide RNAs that remodel target RNA structure for selective editing and reduced nuclease activity, we show that ALTER achieves, on average, 1.9-fold higher C-to-U editing on mRNA targets in HEK293T cells compared with Cas13 editors CURE and RESCUE. Transcriptome-wide RNA-seq revealed similar or lower levels of off-target editing compared to the same Cas13-based editors. Machine learning models predict that far fewer immunogenic peptides will result from ALTER and we show that ALTER is amenable to a validated workflow for artificial intelligence-directed deimmunization. Human Argonaute is repurposed for RNA editing.

mhryu@live.com's insight:

why RNA? Targeting is RNA only. AGO2 uses a small RNA guide to base pair with mRNA; nothing in the design recognizes DNA.  The deaminase was engineered against DNA. ALTER-4 uses A3A K30R;Y132G, reported to have undetectable DNA activity.  Wrong compartment: ALTER-4 is largely excluded from the nucleus, where genomic DNA sits. Adding a nuclear localization sequence (ALTER-4N) removes that protection.

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Efficient scarless gene editing in Pichia pastoris via survival stress-based intramolecular homologous recombination | mre

Efficient scarless gene editing in Pichia pastoris via survival stress-based intramolecular homologous recombination | mre | RMH | Scoop.it
To overcome low efficiency and/or genomic instability induced by DNA cleavage in current genome-editing approaches, a novel pop-in/pop-out-based editing system was developed for Pichia pastoris. An ingenious arrangement of components leads to a more efficient screening by permitting the only type of DNA recombination under defined pressure conditions, in terms of the overall efficiency of gene editing, the system virtually depends on the integration efficiency mediated by single-crossover recombination. It does not rely on exogenous recombinases or programmable nucleases such as Cas9, thereby avoiding nuclease induced double strand breaks and associated off target mutations or chromatin fatigue. This strategy preserves high editing efficiency with no modification to the host’s inherent genetic properties. Relative to site-specific recombination methods, its dual MazF counterselection enables seamless editing, avoiding scar sequence-induced genomic instability. In this study, nearly 100% knockout efficiency and over 86.67% integration efficiency were achieved in the described experimental cases with this system, which provides a new gene-editing tool for synthetic biology in Pichia pastoris.
mhryu@live.com's insight:

counterselection, two mazF expression cassettes driven by distinct promoters (PAOX1 and PLRA3 inducible by methanol and rhamnose, respectively)

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Endophytes for climate-resilient agriculture: Mechanisms and systems-level insights

Endophytes for climate-resilient agriculture: Mechanisms and systems-level insights | RMH | Scoop.it
Endophytic bacteria and fungi that asymptomatically colonize plant tissues represent promising biological resources for developing sustainable and climate-resilient agricultural systems. These beneficial microorganisms establish intimate associations with crops and modulate plant growth, nutrient acquisition, immune responses, and stress physiology through diverse biochemical and molecular mechanisms. Endophytes enhance crop performance by producing phytohormones, solubilizing and mobilizing essential nutrients, improving nutrient-use efficiency, suppressing phytopathogens, inducing systemic resistance, and regulating plant metabolic and antioxidant responses. These functions can improve crop tolerance to major climate-associated stresses, including drought, salinity, heat, and nutrient limitations, while contributing to stable growth and yield under changing environmental conditions. Their potential as biofertilizers, biocontrol agents, biostimulants, and components of integrated crop management offers opportunities to reduce dependence on synthetic fertilizers and pesticides and promote environmentally sustainable agricultural production. This review critically synthesises current knowledge of endophyte diversity, crop colonization, host specificity, plant-microbe signalling, and mechanisms underlying growth promotion, disease suppression, nutrient acquisition, and abiotic stress tolerance. Particular emphasis is placed on multi-omics and systems-level approaches that reveal endophyte-mediated regulation of plant metabolism, immunity, and microbiome assembly. The review also evaluates major constraints limiting agricultural translation, including inconsistent field performance, environmental adaptability, formulation and delivery, host microbe compatibility, ecological interactions, biosafety, and regulatory requirements. Finally, integration of multi-omics, microbiome engineering, synthetic biology, and precision agriculture is proposed as a pathway for developing robust endophyte-based technologies and microbial consortia. Such approaches could facilitate the transition toward low-input, resource-efficient, productive, and climate-resilient agriculture while strengthening long-term food security.
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From genome editing to chromosome engineering in plants | tin

From genome editing to chromosome engineering in plants | tin | RMH | Scoop.it
Engineering large genomic segments is rapidly expanding the scope of plant genome manipulation from individual genes to chromosome-scale redesign. Recent advances in double-strand break-, prime-editing-, recombinase-, and transposase-based technologies now enable programmable deletion, insertion, replacement, duplication, inversion, and translocation of DNA fragments ranging from kilobases to megabases. In this review, we summarize the major strategies for large-fragment genome engineering in plants, compare their strengths and limitations, and discuss their applications in both fundamental plant biology and crop breeding. We further highlight that the integration of artificial intelligence is catalyzing the rapid optimization of large-fragment genome engineering. The ongoing transition from genome editing to chromosome engineering promises to revolutionize crop breeding and plant synthetic biology, ultimately enabling rational design of plant genomes.
mhryu@live.com's insight:

gao c

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Community context redirects evolutionary trajectories under stress | tin

Community context redirects evolutionary trajectories under stress | tin | RMH | Scoop.it
Adaptation to abiotic stress is typically studied in single-species cultures, yet bacteria inhabit and evolve in multispecies communities where neighboring organisms reshape, for example, nutrient availability, redox state, and cellular physiology. We recently demonstrated that interspecies interactions can alter the fitness effects of antibiotic resistance mutations, and we suggest that this reflects a broader principle. Stress-response networks are extensively cross-regulated and draw upon a shared, finite pool of proteomic and energetic resources. Consequently, activation of one pathway constrains others, creating physiological trade-offs. Because microbial interactions routinely perturb the physiological inputs to these networks, they can systematically redirect evolutionary trajectories under abiotic stress. We discuss the evidence, limitations, and implications of this framework for predicting evolution and understanding microbiome stability.
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Microbial resistance from genotype to metabolic phenotype | tin

Microbial resistance from genotype to metabolic phenotype | tin | RMH | Scoop.it
Antimicrobial resistance (AMR) poses an escalating global threat, yet surveillance and mechanistic understanding remain anchored in individual resistance genes, an approach that is inadequate for capturing the ecological, genomic, and metabolic complexity through which resistance emerges and spreads. In this opinion article, we argue that genome-scale metabolic models (GEMs) offer a principled framework for advancing AMR research beyond this gene-centric paradigm. Strain-resolved GEMs embed resistance determinants within metabolic networks, with the potential to generate quantitative, context-dependent phenotypic predictions, including minimum inhibitory concentrations and environment-conditional resistance, that sequence-based tools do not provide. Expanded GEM frameworks incorporating mobile genetic elements, horizontal gene transfer, and community-level interactions support ecology-aware resistance profiling. At the therapeutic level, whole-network modelling can identify metabolic vulnerabilities, synthetic lethal interactions, and microbiome-targeted strategies. Integrating GEMs with multiomics and data-driven approaches represents a critical step toward a mechanism-aware AMR platform connecting surveillance, diagnosis, and drug discovery.
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Efficient permuted intron-exon RNA circularization system based on the LtrB group II Intron from Lactococcus lactis | brvbe

Efficient permuted intron-exon RNA circularization system based on the LtrB group II Intron from Lactococcus lactis | brvbe | RMH | Scoop.it

Circular RNAs (circRNAs) have emerged as promising platforms for stable RNA expression and therapeutic applications, but methods for their generation remain limited. Here, we engineered the Lactococcus lactis LtrB group II intron into a permuted intron-exon (PIE) configuration to enable efficient circRNA formation (circLtrB). Among the tested split designs, LtrB domain IV cleavage yielded the highest circularization efficiency. Although LtrB encodes LtrA maturase required for efficient in vivo splicing, in vitro application of LtrA to the PIE constructs resulted in lower circularization efficiency than self-splicing conditions. We further examined circularization under distinct salt conditions and showed that NH4Cl- and KCl-based splicing buffers independently support high circularization efficiencies (>80%), while producing distinct splicing intermediates, indicating ion-specific mechanistic effects on circularization. Extending outer homology arms did not enhance circularization efficiency, demonstrating that efficient circRNA formation in the circLtrB platform is independent of extended exon pairing interactions. Using this system, we generated circRNAs across a range of coding sequence lengths, highlighting its payload flexibility. To optimize translation, we evaluated multiple internal ribosome entry sites (IRES), including Aichivirus, Crohivirus, CVB3, improved EMCV, HRV, and Salivirus, and found that the CVB3 IRES drove the highest translation efficiency. Linear NLuc showed faster decay kinetics, while circLtrB-NLuc exhibited more sustained expression over time. Transcriptome-wide RNA sequencing revealed comparable innate immune responses between circular and linear RNAs. Together, these results establish circLtrB as a versatile and efficient platform for circRNA production, providing mechanistic insight into group II intron-mediated circularization and expanding the toolkit for functional circRNA engineering.

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Chemically encoded pH-tunable covalent adhesion by a bacterial thioester domain | sadv

Chemically encoded pH-tunable covalent adhesion by a bacterial thioester domain | sadv | RMH | Scoop.it
Thioester domains (TEDs) represent a family of bacterial adhesin domains that mediate covalent anchoring to target ligands via an intramolecular thioester bond. Although the broad distribution of TEDs among Gram-positive bacteria suggests a critical functional role, the biological significance of this covalent mechanism remains unclear. In this study, we demonstrated that TED-mediated covalent anchoring is reversible and that its equilibrium is regulated by pH. Specifically, SfbI-TED from group A Streptococcus binds tightly to fibrinogen at physiological pH, whereas mild acidification to pH 6.0 induces rapid dissociation of the complex. Thermodynamic analyses indicated that this pH responsiveness is largely dictated by the intrinsic pH sensitivity of the thioester-mediated acyl transfer reaction conserved within TEDs, rather than by surface residues specific to individual TEDs. Similar pH-dependent behavior was observed in phylogenetically distinct TEDs, suggesting that pH-responsive adhesion is likely to be a broadly shared feature of TED-containing adhesins across Gram-positive bacteria.
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G4All: a database of experimentally confirmed G-quadruplex-forming sequences | nar

G4All: a database of experimentally confirmed G-quadruplex-forming sequences | nar | RMH | Scoop.it

G-quadruplexes (G4s) are non-canonical nucleic acid structures with critical roles in gene regulation, genomic stability, and disease, making them prime targets for therapeutic and biotechnological applications. However, the absence of a curated, centralized, experimentally validated repository of short (mostly synthetic) G4-forming sequences, paired with appropriate single-stranded or hairpin controls, has limited reproducibility and hindered progress in the field. Here, we introduce G4All, a comprehensive, curated database of G4-forming short DNA and RNA sequences, complemented by rigorously selected non-G4 controls, all studied under roughly similar experimental conditions (generally around 100 mM potassium and near neutral pH). G4All consolidates sequences validated by diverse experimental methods, including circular dichroism, NMR, UV spectroscopy, with annotations for topology, thermal stability, and experimental conditions. By providing both positive and negative datasets, G4All enables rigorous comparative analyses, assay benchmarking, and the development of predictive models. The database supports a broad range of applications, from fundamental studies of G4 biophysics to the rational design of aptamers, as well as benchmarking prediction algorithms. Future developments will expand G4All to include user-submitted datasets and more RNA sequences. Freely accessible at https://g4-all.streamlit.app/, G4All offers a searchable interface and downloadable datasets, establishing a community-driven hub to accelerate discovery and standardization in G4 research.

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A phage-encoded small RNA that mimics chimeric guide to inhibit CRISPR-Cas9 | chm

A phage-encoded small RNA that mimics chimeric guide to inhibit CRISPR-Cas9 | chm | RMH | Scoop.it
CRISPR-Cas9 relies on a dual CRISPR RNA (crRNA)-trans-activating crRNA (tracrRNA) guide, yet whether RNA-based anti-CRISPRs exist for this system has remained unknown. Here, we identify a phage-encoded small non-coding RNA, rAcrIIA1, that adopts an unexpected chimeric crRNA-tracrRNA architecture, faithfully recapitulating the entire single-guide RNA (sgRNA) of Cas9. Cryo-electron microscopy (cryo-EM) structures of the Cas9-rAcrIIA1 binary complex and the Cas9-rAcrIIA1-DNA ternary complex reveal that rAcrIIA1 engages Cas9 nearly identically to the native sgRNA, competitively blocking crRNA and tracrRNA loading and thereby abolishing DNA interference. Strikingly, beyond its natural inhibitory function, rAcrIIA1 is fully reprogrammable: with variable guide sequences, it directs Cas9 for sequence-specific DNA cleavage with efficiency comparable to the canonical sgRNA, and it activates trans-cleavage more potently. Thus, rAcrIIA1 provides an experimentally validated, mechanistically resolved RNA-based inhibitor of CRISPR-Cas9, reveals a distinct anti-CRISPR mechanism through complete sgRNA mimicry, and serves as a versatile bifunctional scaffold for genome editing and diagnostics.
mhryu@live.com's insight:

1str

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Discovery of phage defense systems through component modularity networks | chm

Discovery of phage defense systems through component modularity networks | chm | RMH | Scoop.it
Phage defense systems in bacteria exhibit high degrees of modularity, with sensing, signal transmission, and effector enzymes frequently exchanged among phage defense gene clusters. In this study, we capitalize on this modularity to discover phage defense systems by searching for defense-associated modules in new gene contexts across Pseudomonas aeruginosa genomes. This approach reveals a large and interconnected network of modular components distributed across diverse gene clusters. From over 500 candidate defense systems, we select five for experimental testing and validate three: Dionysus, a TerB-encoding system that interferes with early phage infection (EPI) vesicle formation by jumbo phages; Ophion, a radical S-adenosyl-L-methionine (SAM)-containing system that blocks progression from the EPI vesicle to the nucleus stage during jumbo phage infection; and Hercules, a tightly regulated restriction-modification (RM)-like system. Collectively, we demonstrate that leveraging the modular architecture of phage defense systems is an effective approach to their discovery.
mhryu@live.com's insight:

1str, gene network analysis,

Find conserved gene clusters in regions of genomic plasticity across 541 P. aeruginosa genomes, since over 95% of defense systems live there (Finding the variable regions and recurring gene groups: PPanGGOLiN v1.2.74. panRGP method for the regions of genomic plasticity, which PPanGGOLiN implements.)
That gave 1,040 clusters, of which 548 contained a domain already associated with phage defense. Then build a network where two clusters are linked if they share a gene. 

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Recordanelles for transcriptome-wide single-cell RNA recording in human cells | Nbt

Recordanelles for transcriptome-wide single-cell RNA recording in human cells | Nbt | RMH | Scoop.it

Transcriptomic measurement technologies provide powerful approaches to understand biology but are limited to providing either a high-resolution snapshot at a moment in time or a low-resolution history of transcription constrained to a few genes over a narrow time range. Here, we introduce the ‘recordanelle’, a single-component synthetic organelle capable of recording the transcriptome in human cells. Recordanelles are composed of a mitochondrial membrane anchor, a condensate assembler and a poly(A)-binding protein. We demonstrate that the recordanelle can be engineered to recruit engineered RNAs or a sampling of up to 90% of all endogenous mRNAs and protect them over several days. We further show that transient and dynamic transcriptional responses resulting from inducible promoters or interferon signaling are preserved throughout time within the recordanelle at the single-cell level. This work provides a nondisruptive and unbiased transcriptome-wide single-cell RNA recording technology to enable a deeper understanding of biology. Recordanelles continuously and unbiasedly record the transcriptome throughout time in living mammalian cells.

mhryu@live.com's insight:

1str, llps, three components—a generic RNA-binding domain (RBD), a biomolecular condensate assembler domain and a mitochondrial membrane anchor. Together, the RBD and the assembler domain collect endogenous RNAs in a protective environment, which is stabilized by the mitochondrial membrane anchor at an easily isolatable structure through time and cell division.   In cells expressing an RNA recording organelle (recordanelle) mounted onto the mitochondria, once genes B are expressed upon stimulation, they are captured within the organelle, where they are protected from decay. The RNA content of the entire cell can then be analyzed at a later time point t3, at which the recorded transcripts remain detectable. To improve the signal-to-noise ratio, recordanelles can be purified by mitochondrial extraction

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Data storage with amino acid sequences | tin

Data storage with amino acid sequences | tin | RMH | Scoop.it
Amino acid sequences in peptides and proteins can be used to store data with the advantages of high capacity and stability, offering a solution for storing ever-increasing amounts of data. Compared with peptides, proteins have longer sequences and can be produced at a much lower cost, enabling more efficient data storage and allowing specific functions to be incorporated using established protein techniques. Although data storage using peptides and proteins has been demonstrated, challenges related to cost, throughput, error rates, data density, and scalability remain to be addressed. Emerging technologies to overcome these challenges are under active development, and their successful commercialization could drive a paradigm shift, enabling high-density and very long-term data storage.
mhryu@live.com's insight:

dna

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Next-generation metabolic models: From multi-constraint integration to AI-driven whole-cell kinetic simulation | cin

Next-generation metabolic models: From multi-constraint integration to AI-driven whole-cell kinetic simulation | cin | RMH | Scoop.it
With the advancement of modeling techniques, metabolic models are evolving from static, single-dimensional approaches to dynamic, multidimensional, and hybrid intelligence frameworks, thereby laying the foundation for next-generation computational models in simulating the metabolic activities. The integration of multi-constraint modeling, and artificial intelligence has substantially improved the predictive accuracy and application scope of various metabolic models. These integrated approaches have been demonstrated to accelerate the optimization of model parameters, enhance the understanding of genotype-phenotype relationships, and offer powerful tools for synthetic biology, precision medicine, and biomanufacturing. Nevertheless, current models continue to encounter challenges, including parameter uncertainty, computational efficiency, and scalability issues. Future research will focus on integrating multiscale data with dynamic simulations to enable a transition from descriptive characterization to systematic modeling. This review summarizes the key advances, typical applications, and current challenges of next-generation metabolic modeling, while also outlining future trends in developing whole-cell kinetic models.
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Decoding the rhizosphere immune signaling network: Microbiome-driven modulation of plant immunity and disease resistance | mre

Decoding the rhizosphere immune signaling network: Microbiome-driven modulation of plant immunity and disease resistance | mre | RMH | Scoop.it
Classical plant immunity models rely on pattern-triggered immunity (PTI) and effector-triggered immunity (ETI), yet these frameworks largely overlook the rhizosphere microbiome as a functional determinant of disease resistance. Plants act as holobionts, their root exudates comprising flavonoids, coumarins, benzoxazinoids, strigolactones, and primary metabolites selectively recruit microbial communities whose composition is shaped by host genotype and dynamically reprogrammed under biotic and abiotic stress. Recruited microorganisms return a diverse signal range including flagellin, siderophores, lipopeptides, lactones, mycorrhizal lipochitooligosaccharides, and volatile organic compounds, which are perceived by LRR (leucine rich repeats) and LysM (lysin motif) domain receptors. This in turn engages the salicylic acid, jasmonic acid, and ethylene signaling pathways. The beneficial rhizosphere members predominantly trigger the JA/ET-dependent induced systemic resistance (ISR) through epigenetic mechanisms, including the H3K4me3 deposition at defense loci that establish heritable primed states that enhance the immune response when pathogens attack. This review synthesizes these interactions within the rhizosphere immune signaling network (RIsN) framework. This reconceptualizes the rhizosphere as multi-kingdom signaling systems whose emergent properties including the signal cooperation, competitive interference, and feedback stabilization, collectively determine disease suppression capacity. Climate change threatens the RIsN stability through microbiome dysbiosis while advances in syncoms, spatial metabolomics, and AI-driven network modeling provide new opportunities for predictive and targeted rhizosphere engineering for durable crop protection.
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Engineering sticky microbes: A framework for appraisal of microbial cell-cell adhesion

Engineering sticky microbes: A framework for appraisal of microbial cell-cell adhesion | RMH | Scoop.it
Engineering bacterial consortia is key in biotechnological applications where specific spatial interactions among their components determine system performance. Genetic tools for programming cell-cell binding such as the nanobody-antigen (Nb-Ag; relying on non-covalent binding) and SpyCatcher-SpyTag (Spy; based on covalent linkage) systems are increasingly adopted as assets for enabling specific interactions of interest among otherwise detached members of a given combination of strains or species. Yet, despite the potential of these technologies, a robust metrology to quantify and compare the efficacy, stability, and specificity of inter-cell binding in a consortium is lacking. This work introduces a conceptual and experimental framework to systematically evaluate synthetic binding systems by combining aggregation assays, flow cytometry, and microscopy. Together, these techniques provide detailed insights into the structure and composition of engineered bacterial aggregates. This methodology was benchmarked with two E. coli strains tagged with different fluorescent markers and engineered to surface-display matching adhesins. Under the test conditions, results showed that the Spy system outperformed the Nb-Ag system in terms of aggregation speed and stability. We also applied the same metrics for assessing the efficacy of the Spy system to mediate synthetic consortia of the pathogenic bacterium Enterobacter cloacae. The robustness of the results suggests the proposed framework to become a valuable tool for quantitative studies on designer bacterial consortia.
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