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mhryu@live.com
Today, 3:33 PM
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Invasive aspergillosis most commonly manifests as pulmonary disease. However, in a subset of patients, the fungus disseminates from the lungs to secondary sites of infection. Disseminated disease is associated with markedly worse clinical outcomes than pulmonary infections, underscoring the importance of understanding the biological mechanisms through which Aspergillus can escape from the pulmonary environment. Here, we review the molecular and cellular events that facilitate dissemination of Aspergillus fumigatus, with a focus on interactions at the host–pathogen interface within the vasculature. Additionally, we examine how fungal morphogenesis, adhesion to endothelial surfaces, and penetration of vascular barriers contribute to hematogenous spread. Finally, we highlight areas of open investigation to focus future research efforts.
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mhryu@live.com
Today, 3:15 PM
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Enzymes drive cellular metabolism, yet predicting catalytic properties from amino acid sequences remains challenging. Existing protein language models (PLMs) provide powerful general-purpose representations but are often inefficient for high-throughput screening and insufficiently adapted to enzyme-specific tasks. Here, we propose EnzGFM, an enzyme-specific PLM based on a Mamba-Transformer hybrid architecture with hierarchical pre-training to capture enzyme-specific patterns. Across enzyme property prediction benchmarks, EnzGFM consistently outperforms Transformer-based PLMs with 2–5-fold acceleration, achieving relative improvements of 16.67% in kinetic parameter prediction, 15.69% in enzyme-reaction mapping, 13.19% in EC number classification, and 20.04% in mutation effect assessment. Building on EnzGFM, we develop EnzGFM-Agent, an enzyme-focused agentic pipeline. Experimental validation further suggests that EnzGFM-Agent can enrich beneficial variants within small candidate pools. Together, these results demonstrate that EnzGFM captures enzyme-specific sequence-function patterns, while EnzGFM-Agent translates these predictions into experimentally actionable candidates and can help reduce wet-lab screening burden for practical enzyme engineering. Enzyme function prediction from amino acid sequences remains a central challenge in computational biology, despite recent advances in protein language models. This manuscript introduces EnzGFM, an enzyme-specific hybrid model that improves both accuracy and efficiency across multiple prediction tasks and, together with the EnzGFM-Agent pipeline, demonstrates the ability to identify experimentally validated beneficial variants while reducing screening effort.
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mhryu@live.com
Today, 2:44 PM
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The development of advanced genome engineering tools is crucial for optimizing metabolic pathways in Saccharomyces cerevisiae and achieving efficient biomanufacturing. This study proposes an enhancing multiplex genome editing strategy in S. cerevisiae by employing Escherichia coli-derived single-stranded annealing proteins (SSAPs) combined with S. cerevisiae-derived homologous recombinases (Rad51 and Rad52). The strategy utilizes an SSAP-Rad-Linearized CRISPR (SRLC) platform, which supports efficient simultaneous editing of multiple genomic loci without constructing complex multi-gRNA expression vectors. Co-overexpressing Rad51/Rad52 and E. coli SSAP proteins significantly enhances homologous recombination (HR), allowing precise multi-locus genome editing mediated by short homologous arms. Furthermore, SRLC employs a linearized CRISPR-Cas system to stimulate homologous recombination and enable counter-selection in S. cerevisiae, thereby improving precise multiplex genome editing efficiency. We applied SRLC to engineer the malonyl-CoA metabolic pathway in S. cerevisiae. Through a single round of editing and screening, we constructed a chassis strain with 9 targets simultaneously modification and achieved a 9.6-fold increase in intracellular malonyl-CoA. Using this chassis, 3-hydroxypropionic acid production increased 4.5-fold relative to wild-type S. cerevisiae. This platform offers a robust and scalable tool for S. cerevisiae manipulation and a practical pathway-engineering strategy for building for malonyl-CoA-derived factories.
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mhryu@live.com
Today, 2:23 PM
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Deep learning has advanced RNA secondary-structure prediction by bypassing explicit energy rules to capture long-range dependencies, yet progress is limited less by model scale than by how structures are measured: single scores hide where and why models fail, and benchmark scores can reflect memorization of one dataset rather than genuine generalization. We address this with Shifu, a framework of three coupled parts. Shifu-Corpus is a leakage-audited dataset of 254123 sequences from six databases, with family-aware splits certified free of exact and near-duplicate leaks. The Shifu Trifecta scores a model on three axes (correctness, breadth across diverse RNAs, and whether its confidence can be trusted) rather than one number. Shifu-LMR, a family of compact RNA language models, serves as controlled experiments: changing the training corpus shifts accuracy by 0.13, and a 65- million-parameter model, Shifu-LMR-Nano, leads on correctness while running on a laptop. We release the dataset, code, and model backbones.
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mhryu@live.com
Today, 2:11 PM
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A mechanistic understanding of how genetic variants alter drug-receptor binding is central to precision medicine, drug response prediction, and drug development. Yet, experimental mutation-drug profiling remains slow and expensive, while existing computational approaches often trade accuracy for scalability. We developed BoltzOmics, an interactive, open-source platform that integrates Boltz-2, a deep learning model for biomolecular structure prediction, to rapidly assess mutation effects on drug binding. Starting from amino acid sequences, the workflow queries databases for genetic variants, generates wild-type and mutant protein structures, and screens multiple drugs across variants to predict binding affinity changes. We evaluated BoltzOmics across four targets: hERG, NaV1.5, HER2, and CYP3A4. Predictions achieved Pearson correlations with experimental drug IC50 data up to 0.76 for wild-type proteins and 0.60 for mutants. By enabling scalable, high-throughput assessment of drug-variant interactions, BoltzOmics establishes a practical AI-driven framework for accelerating computational drug discovery and advancing precision medicine research.
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mhryu@live.com
Today, 10:13 AM
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All organisms defend against viral infections through active immunity mechanisms that clear the virus or population-level mechanisms that cause regulated cell death. Recent research increasingly shows that, across all domains of life, these two types of defence systems are coupled such that regulated cell death mechanisms safeguard or back up active immunity.
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mhryu@live.com
Today, 1:48 AM
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In prokaryotic genomes, methylation is an important epigenetic modification that regulates the uptake of foreign DNA; it can also contribute to replication or virulence. We present MPore, a novel method for the database-driven detection of active methyltransferases and their associated target site recognition motifs from Nanopore R10 sequencing data of prokaryotic isolates. In contrast to existing methods, which typically start with the de novo identification of differentially methylated sequence motifs, MPore starts by identifying potential methyltransferase genes by homology search against REBASE; activity is then assessed through a regularized logistic regression model of observed genome-wide methylation patterns, integrating motif and genomic sequence context information. On two benchmarking datasets, 10 bacterial monocultures and two Helicobacter pylori genomes with complex methylation patterns, MPore achieved a combined recall of 93% and a combined PPV of 96%, outperforming Nanomotif (81%/91%), Modkit (66%/4%), and Snappy (89%/50%). Further validation on a well-characterized dataset of Mycoplasma hominis isolates showed perfect agreement with wet-lab-based validation results and demonstrated that MPore could complement REBASE information by disambiguating the specific methylated base in a motif with multiple potential methylation sites. MPore automatically produces integrated visualizations of the identified methyltransferases and observed methylation patterns; the tool is implemented as a user-friendly Snakemake pipeline.
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mhryu@live.com
Today, 1:26 AM
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The paradigm of molecular diagnostics has been transformed by the repurposing of CRISPR-Cas systems from being gene-editing tools to nucleic acid detection engines with remarkable specificity and programmability. Both the SHERLOCK and DETECTR platforms have shown high sensitivity and specificity; however, the requirement of a pre-amplification step to achieve clinically relevant detection limits adds another layer of complexity and cost and is also a potential source of contamination, precluding their use as true point-of-care (POC) tools. The next frontier for CRISPR diagnostics will be the design of biosensors that enable preamplification-free, multiplex, and continuous direct detection of targets. Achieving this goal will involve the very close integration of CRISPR biology with nano-biotechnology, microfluidics, orthogonal Cas enzyme systems, and artificial intelligence (AI). This review aims to provide a comprehensive overview of recent advancements and strategic thinking related to this integration. This review discusses how nanomaterials facilitate signal generation and transduction, how microfluidics automates, multiplexes, and miniaturizes “all-in-one” devices, and how orthogonal CRISPR systems can enable robust multiplexing. We will also probe into the emerging application of AI to accelerate guide RNA design and optimize the performance of CRISPR biosensors. Furthermore, the roles of orthogonality and nanomaterials in real-time, continuous molecular monitoring will be assessed. The review will finally discuss the transformative future applications of high-throughput biomarker discovery and theranostics potential through massively parallelized CRISPR sensing.
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mhryu@live.com
Today, 1:15 AM
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Antiphage systems such as restriction-modification and CRISPR-Cas have DNA substrate specificity mechanisms that enable the identification of invaders. How Gabija, a highly prevalent nuclease-helicase antiphage system, limits phage replication while executing self- vs. non-self-discrimination remains unknown. Here, we show that phage-encoded DNA end-binding proteins that antagonize host RecBCD sensitize phages to Gabija. When targeting a temperate lambda-like phage in Pseudomonas aeruginosa, Gabija prevents phage genome circularization and subsequent replication. DNA end-binding complexes, including a phage exonuclease and a single-stranded DNA (ssDNA)-annealing protein or GamMu dimers that prevent loading of the host repair complex RecBCD, are necessary and sufficient to license phage and plasmid sensitivity to Gabija. Mutant escape phages lacking these DNA end-binding proteins become protected from Gabija by RecBCD translocation activities. RecBCD activity on the bacterial genome, presumably whenever it is linearized, also prevents Gabija from targeting self-DNA. Therefore, we propose that Gabija antagonizes the circularization and replication of linear DNA devoid of RecBCD as a mechanism to identify and antagonize foreign invaders.
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mhryu@live.com
Today, 12:44 AM
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Microbial communities are largely driven by metabolic interactions, whereby species compete for shared resources and exchange byproducts. Such interactions are commonly classified by their sign alone. Yet, theory shows that the strength of interactions and the shape of their distribution impact how many and which species coexist. What this shape looks like in microbial communities and why has rarely been examined. Starting from a consumer-resource model of resource competition and cross-feeding, we find that these metabolic processes generate a skewed distribution with ``many weak, few strong'' interactions -- a pattern previously documented in the food webs of larger organisms. This skew emerges whenever species have different substrate preferences and when metabolite leakage is sufficiently high. Across nine microbial datasets spanning diverse community origins, empirical interactions not only qualitatively display this skewed pattern but quantitatively follow the relationship between higher-order statistics predicted by the model. Generalized Lotka-Volterra (gLV) models, the standard framework for predicting community diversity, typically assume Gaussian interaction strengths. Instead, we show that the observed ``many weak, few strong'' interaction distribution is better captured by a lognormal distribution than the symmetric Gaussian distribution. Sampling interactions in gLV models from a lognormal distribution yields more stable communities in simulations and more accurately predicts the diversity observed in the two datasets where community-assembly experiments were performed. Together, these results reveal a metabolic origin for the ``many weak, few strong'' pattern of microbial interactions and show that using empirically grounded interaction distributions improves predictions of community diversity.
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mhryu@live.com
Today, 12:22 AM
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Bacillus subtilis is a core microbial chassis in biomanufacturing, and establishing efficient gene editing technologies is key to engineering this strain. In conventional CRISPR gene editing technologies, the large size of DNA nucleases leads to difficulties in plasmid construction, low transformation efficiency, and cumbersome multi-round editing operations; therefore, developing miniature gene editing tools can effectively address these issues. Although our group previously established a miniature gene editing tool based on IscB in B. subtilis SCK6, IscB relies on the 5′-CAGGAA-3′ TAM recognition sequence, and 83.36% of the genes in the SCK6 genome harbor no or only one TAM sequence, indicating a bottleneck of restricted editing for IscB in this strain. The novel miniature DNA nuclease TasR does not require a TAM sequence and can thus compensate for the limitation of IscB; however, the applicability of TasR in B. subtilis remains unknown. Therefore, this study first constructed a single plasmid, pBsuTasR, capable of expressing TasR and its guide RNA (tigRNA), which enabled gene deletion of regular-sized fragments in SCK6 with editing efficiencies of 21.7%-78.3%. Subsequently, the capacity of TasR to delete a long DNA fragment (169.9 kb) was evaluated, and it was found that under the guidance of a single tigRNA, the deletion efficiency was 21.73%, whereas after optimizing to two tigRNAs, the efficiency increased to 39.13%. Furthermore, the gene integration capability of pBsuTasR was further tested, and TasR was able to integrate the aprN gene into the amyE locus at an efficiency of 13.3% under the guidance of a single tigRNA, and after increasing to two tigRNAs, the integration efficiency increased to 91.3%. In terms of iterative genome editing, this study developed the pBsu-SRP (Scissors-Rock-Paper) iterative editing system, which automatically cures the editing plasmid from the previous round while performing a new round of gene editing, with sequential gene deletion efficiencies of 4.34%-26.08%, and using this system, the editing cycle can be shortened from 4N days by the conventional method to 3N+1 days. Subsequently, the pBsu-SRP system was successfully used to achieve the integration of two and three copies of the mCherry fluorescent reporter gene in SCK6, and it was found that the fluorescence intensity increased with the copy number. Finally, this study also explored the escape of SCK6 from TasR cleavage and found that mutations in the tigRNA sequence are the cause of the escape. In summary, this study constructed a novel miniature genome editing system in B. subtilis using the TAM-independent nuclease TasR as the core component. This system can not only provide an efficient technical tool for genetic manipulation of industrial microorganisms, but also offer new instrumental support for the iterative engineering and functional optimization of chassis cells in biomanufacturing. genome editing
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mhryu@live.com
July 16, 11:31 PM
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We previously reported the de novo design of three small (<20 kDa), highly soluble synthetic intrinsically disordered proteins (SynIDPs) and demonstrated their utility as solubility tags for proteins and antifouling agents. Building on this work, we now show that these hypersoluble SynIDPs significantly enhance the soluble expression of disulfide-rich proteins (DRPs) of therapeutic relevance, including fibroblast growth factor 21 (FGF-21), interleukin-15 (IL-15), and bovine pancreatic trypsin inhibitor (BPTI). Through SynIDP fusions, we achieve soluble recombinant production of functionally active DRPs containing a single disulfide bond in the E. coli strain BL21(DE3) and up to three nonconsecutive disulfide bonds in the E. coli SHuffle T7 Express strain, without the need for refolding. The resulting SynIDP-DRP fusion proteins retain biological activity, confirming correct folding and disulfide-bond formation with minimal interference from the SynIDP tag, which obviates the need for tag removal. Collectively, these findings highlight the versatility and utility of SynIDPs as molecular tools to advance the production and development of protein therapeutics.
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mhryu@live.com
July 16, 10:56 PM
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Komagataella phaffii (syn. Pichia pastoris) is an important host for the production of recombinant proteins and small molecules, often exhibiting superior performance compared to other heterologous hosts. With advancements in synthetic biology and computational biology, metabolic engineering has become a key strategy for achieving high-level heterologous proteins and small molecules in K. phaffii for industrial and commercial applications. In this review, we provide an overview of advances in K. phaffii metabolic engineering. We first discuss the development of the K. phaffii expression system. Subsequently, we analyze core optimization strategies, including metabolic flux control, metabolic dynamic control, application of system modeling, chassis cell optimization, and recombinant protein and small-molecule production, before finally summarizing the current challenges and future development directions.
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mhryu@live.com
Today, 3:24 PM
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Advances in molecular biology have expanded antimicrobial strategies that traditionally targeted proteins or metabolic pathways to now include RNA, enabling a previously unattainable precision through control of gene expression. The clinical potential of RNA-therapeutics was demonstrated during the COVID-19 pandemic, when mRNA vaccines marked a transformative milestone for RNA-based interventions for viral infections. Increasingly, similar principles are emerging for the treatment of bacterial infections. Antisense oligonucleotides (ASOs) bind complementary mRNA sequences to induce RNase H-mediated degradation or block their translation. Initially developed for genetic and neurodegenerative disorders, ASOs are now emerging as next-generation antibacterials, termed ASOBiotics, designed to silence essential bacterial genes. In this review, we explore the advances of ASO technologies with applications in bacterial pathogens, outlining design considerations while discussing the challenges and opportunities for making precision antibacterial therapeutics.
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mhryu@live.com
Today, 3:11 PM
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Seaweeds (macroalgae) are important primary producers that sustain food webs in coastal ecosystems. Most algae accelerate inorganic carbon assimilation by actively concentrating CO2 in a Rubisco-rich specialized organelle called the pyrenoid. However, the molecular composition of this pathway is unknown in seaweeds. Here, we investigated the intracellular localization of 160 proteins associated with CO2 acquisition in the green seaweed Ulva (Sea lettuce). We assign 68 proteins to different pyrenoid subdomains and identify a consensus Ulva Rubisco binding motif revealing the molecular logic of the Ulva pyrenoid. We reveal Seaweed Ulva Pyrenoid Assembly 1 (SUPA1) as the core pyrenoid assembly factor. We show that Rubisco condensation is driven by a unique mechanism: the helical folding of SUPA1 motifs upon Rubisco binding, combined with steric hindrance that halves the available Rubisco binding sites from eight to four. Our data gives an unprecedented sub-cellular spatial understanding on seaweed carbon fixation and provides insights into the evolution of this important pathway in the global carbon cycle.
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mhryu@live.com
Today, 2:25 PM
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Food safety is a major public concern, with foodborne pathogens such as Staphylococcus aureus, Listeria monocytogenes, Clostridium perfringens, and Vibrio parahaemolyticus causing millions of infections and significant economic losses annually. Phage and endolysin therapies have emerged as promising environmentally friendly strategies for pathogen control. Bacteriophage lytic enzymes, which are proteins produced during the late stage of phage infection, offer advantages over whole phages, including rapid bactericidal action, a broad antibacterial spectrum, and a low risk of inducing resistance. This review summarizes the structure, classification, and lytic mechanism of phage lysins, as well as their application in combating foodborne pathogens across various food matrices, including meat, dairy products, agricultural produce, and seafood. Furthermore, these lysins have demonstrated promising potential in biofilm removal. Meanwhile, this review discusses multiple improvement strategies that have been developed to enhance the activity of lysins against both Gram-positive and Gram-negative bacteria. These include domain truncation, site-directed mutagenesis, and domain shuffling to overcome insufficient stability and suboptimal activity in food environments, as well as co-administration with outer membrane permeabilizers, encapsulation and engineered lysins (e.g., Artilysins, Innolysins, and Lysocins) to breach the outer membrane barrier of Gram-negative bacteria. Furthermore, the introduction of computer-aided and bioinformatics tools has provided new avenues for the high-throughput screening and rational design of lysins. Although challenges such as low screening efficiency, unstable activity in food matrices, non-uniform efficacy endpoints, regulatory data requirements, high production costs, and limited consumer acceptance persist, lysins, as green and efficient natural antimicrobial proteins, still exhibit broad application prospects in food biocontrol.
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mhryu@live.com
Today, 2:15 PM
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Prokaryotic isocitrate dehydrogenase (PIDH) is a conserved and highly versatile enzyme regulating carbon flux between the TCA cycle and the glyoxylate shunt. While most mesophilic organisms encode a single PIDH, the industrial chassis Pseudomonas putida KT2440 harbours two isoforms: a monomeric (IDH) and a dimeric (ICD). The physiological significance of this dual-system in mesophiles remains poorly understood, yet it may provide a framework for understanding metabolic flexibility and flux regulation in biotechnological applications. Here, we biochemically characterized both PIDHs and, through modelling and site-directed mutagenesis, identified key residues (Ser133, Asn136, and Arg140) critical for monomeric catalytic activity and substrate binding. Genetic analysis revealed that the monomeric IDH is essential for growth, whereas the dimeric ICD appears to facilitate high-flux oxidative metabolism. System-level analysis integrating transcriptomics and flux modelling further demonstrated that these isoforms might fuel distinct TCA functional modes. Our results suggest that IDH sustains a basal, carbon-independent mode critical for biosynthetic precursor supply. In contrast, ICD drives a high-flux oxidative mode under glycolytic conditions and is post-translationally inactivated under gluconeogenic conditions, favouring the glyoxylate cycle. Taken together, these findings support a model in which specialized isoenzymes with conditional redundancy, rather than simple redundancy, in P. putida. This dual-enzyme system enables the cell to balance energy production with biosynthetic demands, which might facilitate metabolic adaptation under fluctuating environmental conditions. Our results provide a potential modular framework for engineering central metabolism to optimize precursor provisioning in microbial cell factories.
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mhryu@live.com
Today, 1:32 PM
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Cells have evolved to defend against perturbations by maintaining their intrinsic homeostasis to survive. However, no intrinsic pathway exists for them to expel new-to-biology synthetic nanostructures. Here we establish crosstalk between supramolecular transformations and genetic responses, achieving programmable influx–efflux cycles of nano-assemblies in living bacterial cells to restore redox and energy homeostasis. Specifically, a model photosensitizer–peptide conjugate undergoes multiple redox cycles between methionine and methionine sulfoxide (MetO), resulting in reversible morphological transformations between nanofibers (NFs) and nanoparticles (NPs). Upon irradiation, the oxidized peptide NPs are internalized into bacteria. To counteract the perturbations caused by internalized NPs, engineered bacteria activate the expression of MetO reductases in response to photo-oxidative stress. The internalized NPs are intracellularly enzymatically reduced such that they are expelled as reduced NFs, setting the stage for subsequent cycles. The concept presented here paves the way for the interlinked network between dynamic supramolecular assemblies and cellular regulatory behaviors. Cells have evolved defense pathways to maintain homeostasis against external perturbations, but not against new-to-nature nanomaterials, which can irreversibly accumulate and induce cell stress. Now, programmable peptide nanoassemblies have been designed that can morphologically transform in influx–efflux cycles in response to restoring redox homeostasis in bacterial cells.
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mhryu@live.com
Today, 9:51 AM
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In this Genome Watch, we explore how the ecological memory of microbiomes shapes transgenerational stress resilience in plants.
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mhryu@live.com
Today, 1:36 AM
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Seaweed plays a crucial role in carbon cycling and is expected to be a valuable resource for sustainable biomass, with applications in biofuel production, human nutrition, and animal feed. Although seaweed has historically been used as a feed source for livestock grazing near coastlines, the process by which it is digested in the rumen remains unknown. Here, we show how the brown alga Saccharina latissima is catabolized within the rumen ecosystem of two different ruminant species using in vivo and in vitro experimental systems. Evidence of digestion was obtained using a combination of animal models, bacterial imaging, multilayered meta-omics, and enzyme biochemistry. Our results demonstrate that geographically distinct ruminants harbor conserved alginate utilization loci, of which essential enzymes were expressed in response to S. latissima in the diet. While core enzymes involved in alginate metabolism have been maintained throughout populations, ancillary enzymes appear to be gained or lost through gene duplication or loss events. The conservation of these systems indicates that the ruminant microbiome retains a latent capacity to metabolize marine polysaccharides. Here, the authors reveal conserved enzymes in geographically distinct ruminant microbiomes that break down brown seaweed alginate, showcasing the rumen’s remarkable capacity to adapt to novel dietary polysaccharides.
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mhryu@live.com
Today, 1:18 AM
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Bottom-up membrane reconstitution has become a powerful framework to investigate the physical principles governing membrane organization and function in highly controlled environments. Among the broad range of available model systems, supported lipid bilayers (SLBs) and giant unilamellar vesicles (GUVs) have emerged as particularly versatile platforms compatible with live optical imaging. In the present mini-review, we summarize recent advances in the preparation and application of these micron-scale membrane systems. We discuss how SLBs and GUVs have enabled major insights into membrane-associated protein assembly, membrane curvature sensing and remodeling, permeability, and cytoskeletal organization. We further highlight emerging developments, including suspended membranes, membrane–coacervate interactions, and the use of GUVs as chassis for bottom-up synthetic biology. Finally, we discuss future perspectives for the field, particularly the growing effort in interfacing synthetic membrane systems and living cells, with potential applications in biomedicine.
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mhryu@live.com
Today, 1:05 AM
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Plant roots are hotspots for interactions with soil microbes, where a characteristic bacterial community structure is formed. Plant specialized metabolites often play pivotal roles in this assembly process. However, the molecular basis underlying root microbiota responses to these bioactive compounds, and how such metabolic interactions shape the assembly of host-specific root microbiota, remain largely unknown. Nicotine is a toxic alkaloid predominantly produced by the genus Nicotiana, and the genus Arthrobacter is known as one of the nicotine-degrading bacteria in the tobacco root microbiota. In this study, we used the tobacco–Arthrobacter interaction system as a model and integrated comparative genomics and experimental genetic manipulation assays to uncover the role of bacterial catabolism capacity for host specialized metabolites in shaping host-specific root microbiota. Nicotine catabolism genes are uniquely found in the Arthrobacter strains derived from nicotine-containing environments, and this restricted gene distribution is driven by a plasmid-mediated horizontal gene transfer. To assess the ecological consequences of this genomic adaptation in Arthrobacter fitness in tobacco roots, we characterized the nicotine utilization ability of Arthrobacter and conducted adaptation assays under in planta conditions using genetically manipulated Arthrobacter strains and tobacco mutants impaired in nicotine catabolism and biosynthesis, respectively. Nicotine improves Arthrobacter colonization of tobacco roots through a catabolism-dependent mechanism. Bacterial community analysis using a synthetic community approach further demonstrated that this metabolic adaptation enhances Arthrobacter fitness within tobacco root microbiota. Our findings illustrated that bacterial catabolic capacity toward host-derived plant specialized metabolites is key for successful root colonization. This metabolic adaptation is driven by plasmid-mediated horizontal gene transfer and ultimately shapes the structure of the root microbiota community.
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mhryu@live.com
Today, 12:26 AM
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Prokaryotic taxonomy now relies on both marker-gene and genome-wide sequence comparisons, but these methods differ in taxonomic range, scalability, and sensitivity to genome quality. Here, we benchmarked four commonly used approaches, including 16S rRNA identity, FastANI, Mash distance, and FastAAI/Jaccard similarity across a dataset of 30,495 prokaryotic type-strain genomes. Type-strain genomes provide nomenclatural anchors for validly named species, making them a useful framework for evaluating how sequence-based methods correspond to current taxonomic assignments. We evaluated method behavior across taxonomic ranks from species to domain and separated initial method failures from threshold-based failures. When clean full-length 16S rRNA sequences were available, same-species comparisons passed the empirical threshold in >97% of cases. However, a usable full-length 16S rRNA sequence was unavailable for 4,551 of the 16,402 same-species comparisons (28%), limiting marker-gene-based analysis. In addition, 16S rRNA identity ranges overlapped across higher taxonomic ranks, limiting the use of universal rank-specific cutoffs. FastANI provided strong species-level resolution, with same-species comparisons passing the empirical threshold in approximately 88% of cases but was less informative at deeper ranks. Mash enabled rapid genome-scale screening, although its distance values require careful interpretation beyond close relatives. FastAAI provided a genome-wide amino-acid signal, with approximately 92% of same-species comparisons passing the empirical threshold and was especially useful for comparisons beyond the species boundary. Overall, no single method performed optimally across all taxonomic levels. These results support a rank-aware benchmarking framework in which 16S rRNA, FastANI, Mash, and FastAAI are interpreted as complementary tools, with attention to genome quality, missing data, and method-specific failure modes.
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mhryu@live.com
July 16, 11:56 PM
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Food enzymology is entering a new era driven by the convergence of metagenomics, artificial intelligence, and synthetic biology. While traditional food processes rely on a limited repertoire of established biocatalysts, metagenomic and multiomics approaches now provide access to vast reservoirs of unexplored enzymatic diversity. Simultaneously, advances in protein structure prediction, functional modeling, and de novo protein design are transforming enzyme discovery from a largely empirical process to a predictive discipline. In this Perspective, we discuss how these technologies will enable the development of tailored biocatalysts for sustainable, precise, and next-generation food processing applications.
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mhryu@live.com
July 16, 11:03 PM
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Mobilizable plasmids are typically used in metabolic engineering studies, especially for their small size, to express heterologous proteins in new host organisms to manipulate their metabolism. R. palustris is a non-model soil bacterium of interest that is well-known for its extensive metabolic versatility, being able to accumulate a wide range of industrially relevant bioproducts, such as polyhydroxybutyrate, n-butanol, hydrogen, and other lignin-derived compounds. However, many of these non-model organisms are more genetically recalcitrant, and the rules of genetic stability, or even plasmid stability, can change drastically from organism to organism. This study investigates the effects of pBHR1’s native mobilization protein, MobV, on the retention of pBBR1 origin plasmids in R. palustris, and the effects of supercoil regulation on both plasmid stability, as well as plasmid-based gene expression. Mobilization proteins participate in horizontal gene transfer between bacterial species. Through two functional assays, a relaxation and a conjugation assay, we determine that the relaxation mechanism is similar to a previously annotated mobilization protein, MobM, and confirm that R. palustris is able to participate in conjugation using its two native type IV secretion systems, respectively. Using flow cytometry, we determine that mutations to various homologous active sites deleteriously impact plasmid expression. Finally, through RT-qPCR, we also determine that the presence of the mobilization protein confers a large positive effect on copy number, where its absence reduces the copy number from 44.27 ± 2.00 copies per cell to 22.86 ± 0.63.
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