Molecular Microbiology最新文献

{"title":"A Cas12a Toolbox for Rapid and Flexible Group B Streptococcus Genomic Editing and CRISPRi.","authors":"G H Hillebrand, S C Carlin, E J Giacobe, H A Stephenson, J Collins, T A Hooven","doi":"10.1111/mmi.70022","DOIUrl":"10.1111/mmi.70022","url":null,"abstract":"<p><p>Streptococcus agalactiae (group B Streptococcus; GBS) is a leading cause of neonatal sepsis and meningitis. Despite advances in molecular microbiology, GBS genome engineering remains laborious due to inefficient mutagenesis protocols. Here, we report a versatile and rapid Cas12a-based toolkit for GBS genetic manipulation. We developed two shuttle plasmids-pGBSedit for genome editing and pGBScrispri for inducible CRISPR interference-derived from an Enterococcus faecium system and optimized for GBS. Using these tools, we achieved targeted gene insertions, markerless deletions, and efficient, template-free mutagenesis via alternative end-joining repair. Furthermore, a catalytically inactive dCas12a variant enabled inducible gene silencing, with strand-specific targeting effects. The system demonstrated broad applicability across multiple GBS strains and minimal off-target activity, as confirmed by whole-genome sequencing. In benchmarking, template-less Cas12a mutagenesis yielded sequence-confirmed mutants in ~7 days and homology-directed edits in ~7-14 days; aTC-resistant colonies arose at ~10^-4 of uninduced CFU, and 27%-65% of resistant clones carried the intended homology-directed edit depending on locus and homology arm length (e.g., ~27% markerless deletion; ~35% insertion; 65% with 1 kb arms). These workflows provide a rapid alternative to temperature-sensitive plasmid mutagenesis protocols that typically require ≥ 4 weeks. This Cas12a-based platform offers an efficient, flexible, and scalable approach to genetic studies in GBS, facilitating functional genomics and accelerating pathogenesis research.</p>","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":" ","pages":"449-461"},"PeriodicalIF":3.1,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12588400/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145054617","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Small RNA Derived From the 5' End of the IS200 tnpA Transcript Regulates Multiple Virulence Regulons in Salmonella typhimurium.","authors":"Ryan S Trussler, Naomi-Jean Q Scherba, Hoda Kooshapour, Michael J Ellis, Konrad U Förstner, Matthew Albert, Alexander J Westermann, David B Haniford","doi":"10.1111/mmi.70016","DOIUrl":"10.1111/mmi.70016","url":null,"abstract":"<p><p>The insertion sequence IS200 is widely distributed in Eubacteria. Despite its prevalence, IS200 does not appear to be mobile and as such is considered an ancestral component of bacterial genomes. Previous work in Salmonella enterica revealed that the IS200 tnpA transcript is processed to form a small, highly structured RNA (5'tnpA) that participates in the posttranscriptional control of invF expression, encoding a key transcription factor in this enteropathogen's invasion regulon. To further examine the scope of 5'tnpA transcript integration into Salmonella gene expression networks, we performed comparative RNA-seq, revealing the differential expression of over 200 genes in a Salmonella SL1344 5'tnpA disruption strain. This includes the genes for the master regulators of both invasion and flagellar regulons (HilD and FlhDC, respectively), plus genes involved in cysteine biosynthesis and an operon (phsABC) encoding a thiosulfate reductase complex. These expression changes were accompanied by an 80-fold increase in Salmonella invasion of HeLa cells. Follow-up experimentation suggested an additional direct target of 5'tnpA to be the small RNA PinT, which has previously been shown to be a negative regulator of invasion genes through its inhibitory action on key transcription factors governing the Salmonella pathogenicity island 1 regulon. This study provides a powerful new example of bacterial transposon domestication that is based not on the production/use of a regulatory protein or regulatory DNA sequences, but on the function of a transposon-derived small RNA.</p>","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":" ","pages":"413-432"},"PeriodicalIF":3.1,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12594629/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144847666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"WhiB6 Transduces Contact-Dependent Signaling in Mycobacterium smegmatis and Coordinately Induces Both ESX-1 and ESX-4.","authors":"Jill G Canestrari,Emma C Gordon,Spencer A Bruce,Erica Lasek-Nesselquist,Sadie R Schultz,Hannah A Marietta,Kyle J Biegas,Benjamin M Swarts,Matthew M Champion,Keith M Derbyshire,Todd A Gray","doi":"10.1111/mmi.70030","DOIUrl":"https://doi.org/10.1111/mmi.70030","url":null,"abstract":"Bacteria have evolved complex conditional pathways that respond to environmental stresses and signals. We use conjugation in Mycobacterium smegmatis to identify contact-recognition and response pathways that mediate interactions between donor and recipient cells. Contact with a compatible donor cell initiates a response in the recipient that requires the ESX-1 secretion system and subsequently activates the dormant ESX-4 secretion system. The links of this signal transduction pathway, the mechanism of coordination and dependency between ESX-1 and ESX-4 secretion systems, are unknown. Previous studies identified SigM as a cell-contact responsive sigma factor dedicated to activating ESX-4. WhiB proteins are iron-sulfur-binding stress-response transcription factors exclusively found in Actinobacteria. WhiB6 has been shown to regulate ESX-1 associated gene expression in other mycobacteria. Here, we show that WhiB6 is required both for conjugation and for transducing cell-contact dependent signaling in the recipient cell. Our RNA-seq, ChIP-seq, and proteomic profiling data define a WhiB6 regulon that supports conjugative cell-cell interaction. The WhiB6 regulon includes genes encoding ESX-1, ESX-4, SigM, as well as dispersed operons that likely support ESX secretion. Our data demonstrate that WhiB6 is epistatic to SigM and ESX-4 in this signal transduction pathway. This work shows that WhiB6 functions as a signal transduction node in recipient cells: it coordinates the expression of two ESX systems and it also induces uncharacterized proteins that collectively constitute a complete secretion response to recipient contact with a donor cell.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"53 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2025-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145357622","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Molecular Characterization of the Group A Streptococcus Virulence-Regulatory System FasBCAX.","authors":"Sushila Baral,Roshika Roshika,Clay P Renshaw,Ameya Singh,Ashna Prabhu,Ira Jain,Rebekah Woolsey,David Quilici,Yftah Tal-Gan,Paul Sumby","doi":"10.1111/mmi.70029","DOIUrl":"https://doi.org/10.1111/mmi.70029","url":null,"abstract":"By regulating the assortment and abundance of its virulence factors at different anatomic sites, the group A Streptococcus (GAS) can cause a range of human diseases. The Fas regulatory system is encoded by a four-gene locus, fasBCAX, with fasX encoding the FasX small regulatory RNA effector molecule. FasX post-transcriptionally regulates target mRNAs through well-characterized mechanisms. Less characterized are the layers of regulation that occur upstream of FasX activity, such as how the products of the fasBCA genes enhance FasX abundance 100-fold. Here, we present data consistent with FasBCA forming a three-component regulatory system, with FasBC being sensor kinase-like proteins that, upon recognizing one or more signals, heterodimerize and phosphorylate FasA, with phosphorylated FasA binding to the fasX promoter and inducing transcription. We identified key amino acids involved in phosphate flow, including H246 of FasC and D60 of FasA, and demonstrated that certain domains (e.g., the kinase domain of FasC) are dispensable for activity. Additionally, we show that a proteinaceous factor within human plasma activates the Fas system. This work represents the first molecular analysis of the Fas proteins which, by modulating FasX levels, play a critical role in the ability of GAS to coordinately regulate virulence factor production.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"16 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2025-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145311703","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization of a Regulatory Network Promoting Cell Fate Segregation in the Myxococcus xanthus Biofilm.","authors":"Shelby Kasto,Penelope I Higgs","doi":"10.1111/mmi.70028","DOIUrl":"https://doi.org/10.1111/mmi.70028","url":null,"abstract":"Most bacterial populations exhibit phenotypic heterogeneity to increase fitness in rapidly changing environmental conditions. Myxococcus xanthus is an environmental bacterium that displays pronounced phenotypic heterogeneity in its complex lifecycle. Under nutrient limitation, M. xanthus produces a specialized biofilm in which cells segregate into two spatially distinct fates: fruiting bodies filled with spores and a persister-like peripheral rod population. Little is known about the regulatory mechanisms controlling peripheral rods. To begin to investigate this cell fate segregation mechanism, we focused on the EspAC signaling system, which controls the accumulation of MrpC, a central transcription factor necessary to induce fruiting body formation. Single-cell reporters and in situ confocal microscopy demonstrated that expression of the esp genes is enriched in the peripheral rods. We identified three transcription factors necessary for espAC transcriptional control: MrpC, FruA, a transcription factor that coordinates sporulation within fruiting bodies, and the xenobiotic response element, Xre0228. We demonstrate that MrpC directly activates espA and espC; FruA represses espC but not espA; and Xre0228 activates espA but represses espC. These genetic interactions fit common network motifs that promote or stabilize phenotypic heterogeneity. We propose a model by which cell fate segregation is directed, stabilized, and tuned to environmental conditions.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"45 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2025-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145311705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Panduratin A Induces Autophagy Through AMPK Activation Independent of mTOR Inhibition and Restricts Mycobacterium tuberculosis in Host Macrophages.","authors":"Thomanai Lamtha,Olabisi Flora Davies-Bolorunduro,Sureeporn Phlaetita,Chernkhwan Kaofai,Phongthon Kanjanasirirat,Tanawadee Khumpanied,Napason Chabang,Bamroong Munyoo,Patoomratana Tuchinda,Suparerk Borwornpinyo,Supawan Jamnongsong,Somponnat Sampattavanich,Prasit Palittapongarnpim,Marisa Ponpuak","doi":"10.1111/mmi.70025","DOIUrl":"https://doi.org/10.1111/mmi.70025","url":null,"abstract":"Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains a major global health burden, especially with the increasing prevalence of drug-resistant strains. There is an urgent need for new therapeutics that act via alternative mechanisms. Autophagy, a vital cell-autonomous defense process, allows macrophages to degrade intracellular pathogens such as Mtb and has gained attention as a potential target for host-directed therapy. In this study, we conducted a high-content imaging screen of herb-derived compounds to identify autophagy inducers in RAW264.7 macrophages. Panduratin A (NPA), a natural compound from Boesenbergia rotunda, was found to potently induce autophagy. NPA promoted autophagic vacuole formation in a dose-dependent fashion at low micromolar levels. Its autophagy-inducing effect was validated using RFP-GFP-LC3 dual fluorescence assays and immunoblotting in the presence of bafilomycin A1. Further mechanistic analysis revealed that NPA activates autophagy through AMPK activation, independent of mTOR inhibition. Importantly, NPA significantly promoted intracellular Mtb clearance and increased colocalization of Mtb with autophagosomes and lysosomes, in a manner dependent on Beclin-1. These findings highlight NPA as a potent enhancer of macrophage antimicrobial responses via autophagy, supporting its potential as a candidate for host-directed adjunctive therapy against TB.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"154 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2025-09-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145140449","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Targeted Deletion of the Cytopathogenic Toxin A Gene in Sneathia vaginalis","authors":"Rishi M. Ray, Phoebe V. Bridy, Aubree G. Musicant, Shiny Chandravel, Youstina Y. Aziz, Jasmine C. Cruz, Kimberly K. Jefferson","doi":"10.1111/mmi.70024","DOIUrl":"https://doi.org/10.1111/mmi.70024","url":null,"abstract":"<jats:italic>Sneathia vaginalis</jats:italic> is a common component of the vaginal microbiome and is emerging as a marker for preterm birth. It produces the cytopathogenic toxin A (CptA), which is capable of lysing human red blood cells and permeabilizing epithelial cells. However, the role of CptA and other potential virulence factors in pathogenesis has been difficult to characterize due to the lack of genetic tools for targeted deletion in <jats:styled-content style=\"fixed-case\"><jats:italic>S. vaginalis</jats:italic></jats:styled-content>. The objective of this study was to create the first isogenic gene deletion mutant in <jats:styled-content style=\"fixed-case\"><jats:italic>S. vaginalis</jats:italic></jats:styled-content>. We chose the <jats:italic>cptA</jats:italic> gene as a target for deletion because of its role in virulence. We characterized the restriction‐modification profile in <jats:styled-content style=\"fixed-case\"><jats:italic>S. vaginalis</jats:italic></jats:styled-content> to increase the chances that exogenous DNA would resist restriction digestion, and we identified an antibiotic resistance cassette that is functional in this species. We identified a genetic locus encoding a Dam methylase and a restriction endonuclease with DpnII‐like activity in <jats:styled-content style=\"fixed-case\"><jats:italic>S. vaginalis</jats:italic></jats:styled-content> strain SN35. By convention, this newly described restriction endonuclease would be named SvaSI for <jats:styled-content style=\"fixed-case\"><jats:italic>S. vaginalis</jats:italic></jats:styled-content> SN35. Using plasmid DNA purified from a Dam+ <jats:styled-content style=\"fixed-case\"><jats:italic>E. coli</jats:italic></jats:styled-content> strain to evade SvaSI restriction, we successfully replaced <jats:italic>cptA</jats:italic> with an erythromycin resistance cassette encoding the <jats:italic>ermF</jats:italic> and <jats:italic>ermAM</jats:italic> genes, creating the first genetically engineered deletion mutation in this species. Results revealed that CptA is necessary for the hemolytic and cytopathogenic activities of <jats:styled-content style=\"fixed-case\"><jats:italic>S. vaginalis</jats:italic></jats:styled-content>. This work is a resource that lays the foundation for the development of additional genetic tools for <jats:styled-content style=\"fixed-case\"><jats:italic>S. vaginalis</jats:italic></jats:styled-content> and facilitates the characterization of additional genes in this emerging pathogen.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"25 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145116552","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Type IV Pili-Associated Secretion of a Biofilm Matrix Protein From Clostridium perfringens That Forms Intermolecular Isopeptide Bonds","authors":"Sarah E. Kivimaki, Samantha Dempsey, Collette Camper, Julia M. Tani, William K. Ray, Ian K. Hicklin, Richard F. Helm, Crysten E. Blaby-Haas, Anne M. Brown, Stephen B. Melville","doi":"10.1111/mmi.70020","DOIUrl":"https://doi.org/10.1111/mmi.70020","url":null,"abstract":"<i>Clostridium perfringens</i> is a gram-positive, anaerobic, spore-forming bacterial pathogen of humans and animals. <i>C. perfringens</i> also produces type IV pili (T4P) and has two complete sets of T4P-associated genes, one of which has been shown to produce surface pili needed for cell adherence. One hypothesis about the second set of T4P genes is that they comprise a type II secretion system (TTSS) like those found in gram-negative bacteria, but for gram-positive bacteria, the TTSS would aid transit across the thick peptidoglycan (PG) layer. The secretome of mutants lacking type IV pilins was examined, and a single protein, BsaC (CPE0517), was identified as being dependent on pilin PilA3 for secretion. The <i>bsaC</i> gene is in an operon with genes encoding a SipW signal peptidase and two putative biofilm matrix proteins, BsaA and BsaB, both of which have remote homology to <i>Bacillus subtilis</i> biofilm protein TasA. Since BsaA forms long oligomers that are secreted, we analyzed BsaA monomer interactions with <i>de novo</i> modeling. These models projected that the monomers formed isopeptide bonds as part of a donor strand exchange process. Mutations in residues predicted to form the isopeptide bonds led to the loss of oligomerization, supporting an exchange and lock mechanism, and isopeptide bonds were detected by mass spectrometry methods. Phylogenetic analysis showed the BsaA family of proteins is widespread among bacteria and archaea, but only a subset is predicted to form isopeptide bonds.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"17 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145103805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Role of the [2Fe‐2S] Cluster of Escherichia coli IscR in Responding to Redox‐Cycling Agents","authors":"Rajdeep Banerjee, Erin L. Mettert, Angela S. Fleischhacker, Patricia J. Kiley","doi":"10.1111/mmi.70021","DOIUrl":"https://doi.org/10.1111/mmi.70021","url":null,"abstract":"The mechanisms by which cells respond to growth inhibitory redox‐cycling agents is only partially understood. In <jats:styled-content style=\"fixed-case\"><jats:italic>Escherichia coli</jats:italic></jats:styled-content> K12, the IscR regulon, which includes the ISC and SUF Fe‐S cluster biogenesis machineries, is differentially expressed in response to these agents. Here, we report how one redox‐cycling agent, phenazine methosulfate (PMS), regulates IscR activity via its [2Fe‐2S] cluster cofactor. A direct role for IscR in mediating the response to PMS was inferred from the PMS‐dependent weakening of [2Fe‐2S]‐IscR binding to an <jats:italic>isc</jats:italic> operon type 1 DNA site in vitro. This decrease in DNA binding was attributed to the accompanying oxidation of its [2Fe‐2S]<jats:sup>1+</jats:sup> cluster. Exposure of anaerobic cultures to PMS leads to increased <jats:italic>isc</jats:italic> expression, as expected from IscR cluster oxidation and impaired binding to type 1 sites in the <jats:italic>isc</jats:italic> promoter. However, this same anaerobic PMS treatment did not change expression of type 2 site promoters, such as <jats:italic>suf</jats:italic>, which require IscR that lacks an Fe‐S cluster (apo‐IscR) for effective transcriptional regulation. In contrast, PMS exposure under aerobic conditions significantly increased both <jats:italic>isc</jats:italic> and <jats:italic>suf</jats:italic> expression, indicating the formation of both [2Fe‐2S]<jats:sup>2+</jats:sup>‐IscR and apo‐IscR. This effect was partially attributed to superoxide generation by PMS under aerobic conditions, as evidenced by a superoxide dismutase‐deficient mutant showing a modest impact on <jats:italic>isc</jats:italic> and <jats:italic>suf</jats:italic> expression. Together, these findings provide new insights into redox‐cycling dependent regulation of IscR activity and highlight the distinct activities of apo‐IscR, [2Fe‐2S]<jats:sup>2+</jats:sup>‐IscR and [2Fe‐2S]<jats:sup>1+</jats:sup>‐IscR in controlling the IscR regulon.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"3 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145035311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Staphylococcus aureus COL: An Atypical Model Strain of MRSA That Exhibits Slow Growth and Antibiotic Tolerance due to a Mutation in PRPP Synthetase.","authors":"Claire E Stevens, Ashley T Deventer, Paul R Johnston, Phillip T Lowe, Alisdair B Boraston, Joanne K Hobbs","doi":"10.1111/mmi.70000","DOIUrl":"10.1111/mmi.70000","url":null,"abstract":"<p><p>Methicillin-resistant Staphylococcus aureus (MRSA) has been a pathogen of global concern since its emergence in the 1960s. As one of the first MRSA strains isolated, COL has become a common model strain of S. aureus. Here we report that COL is, in fact, an atypical strain of MRSA that exhibits slow growth and multidrug tolerance. Genomic analysis identified three mutated genes in COL (rpoB, gltX and prs) with links to tolerance. Allele swapping experiments between COL and the closely-related, nontolerant Newman strain uncovered a complex interplay between these genes. However, Prs (phosphoribosyl pyrophosphate [PRPP] synthetase) accounted for most of the growth and tolerance phenotype of COL. Biochemical and transcriptomic analysis revealed that COL does not exhibit slow growth as a result of partial stringent response activation, as previously proposed. Instead, the COL Prs mutation greatly reduces the PRPP synthetase activity of the enzyme and leads to downregulation of pyrimidine, histidine, and tryptophan synthesis, three pathways that rely on PRPP. Overall, our findings indicate that COL is an atypical, antibiotic-tolerant strain of MRSA whose isolation predates the previous first report of tolerance among clinical isolates. Characterization of clinical Prs mutations and their relationship with tolerance requires further investigation.</p>","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":" ","pages":"189-203"},"PeriodicalIF":3.1,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12423488/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144258515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}