Journal of Bacteriology最新文献

{"title":"A phage-derived reconfigurable effector associated with an actinobacterial contractile nanomachine tailors bacterial responses to competition.","authors":"Toshiki Nagakubo, Tatsuya Nishiyama, Shumpei Asamizu, Hiroyasu Onaka, Nobuhiko Nomura, Masanori Toyofuku","doi":"10.1128/jb.00532-25","DOIUrl":"https://doi.org/10.1128/jb.00532-25","url":null,"abstract":"<p><p>Contractile injection systems (CISs) are derivatives of phage tails and are widely distributed in prokaryotes. CISs load cognate effectors and eject them through contractile actions resembling those of phage tails. Ejected effectors play central roles in CIS functionality by acting on target cells and mediating various biological processes. Here, we report a novel group of CIS effectors related to phage tape measure protein, the transmembrane component of the phage infection machinery. This group is broadly distributed within the class Actinobacteria, one of the bacterial classes in which CIS gene clusters are highly conserved, and is represented by Sle1, a cognate effector of the intracellularly localized <i>Streptomyces lividans</i> phage tail-like nanoparticle (SLP). This effector is associated with Sle2, which contains a CIS effector core domain and interacts with the SLP core component. Sle1 is packaged inside SLP and is translocated to lipid membranes along with SLPs. The functional domain of Sle1 enriches the membrane-associated subproteome in <i>S. lividans</i> and <i>E. coli</i>. This effect modifies the physiological properties of <i>S. lividans</i>, ultimately enhancing its adaptation to microbial competition. In addition, we revealed that Sle1-type effectors conserved among actinobacterial species are structurally and functionally diverse in their functional domains. One of them from <i>Micromonospora eburnea</i> constitutes a novel toxin-antitoxin system, and introducing its functional domain into Sle1 reprograms the phenotypic responsiveness of <i>S. lividans</i> to neighboring bacteria. Our findings illustrate that phage elements can be incorporated into CISs as reconfigurable platforms for bacterial adaptation to various environmental conditions.IMPORTANCEBacterial CISs have attracted interest for their importance in microbial ecology and potential in biotechnological applications. However, understanding of their functional diversity is currently limited because many CIS effectors remain unannotated due to a lack of inferable structural and genetic signatures. Our findings on Sle1 and its relatives illuminate a previously unidentified class of CIS effectors with phage tape measure protein-related modular architecture, association with the CIS effector core domain, and wide distribution within the major class of Actinobacteria, substantially expanding the known repertoire of effector classes. The impact of Sle1 on <i>S. lividans</i> suggests a link between CIS effectors and bacterial adaptation to environmental conditions, highlighting unexplored functional diversity of CIS effectors as tuners of bacterial phenotypes in communities.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0053225"},"PeriodicalIF":3.0,"publicationDate":"2026-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147838352","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The MarR family regulator RmaH underlies the trade-off between acid sensitivity and antibiotic tolerance in <i>Lactococcus lactis</i>.","authors":"Qianqian Song, Peng Zhang, Hao Wu, Hongji Zhu, Jiaheng Liu, Jianjun Qiao","doi":"10.1128/jb.00502-25","DOIUrl":"https://doi.org/10.1128/jb.00502-25","url":null,"abstract":"<p><p>Microorganisms exhibit remarkable adaptability to diverse environmental stresses through transcriptional reprogramming. Here, we focused on the MarR family regulator RmaH in <i>Lactococcus lactis</i>, which orchestrated a pivotal trade-off: enhancing tolerance to the bacteriocin nisin and the antibiotic vancomycin at the expense of acid resistance. RmaH directly activated genes for cell wall and membrane lipid biosynthesis, leading to a thicker cell wall, and repressed the arginine deiminase pathway, attenuating acid tolerance. Integrated transcriptomic, chromatin immunoprecipitation-sequencing, and electrophoretic mobility shift assay identified RmaH as a global transcription regulator, modulating processes, including amino acid transport and metabolism, cell wall/membrane/envelope biogenesis, carbohydrate transport and metabolism, and nucleotide transport and metabolism. The molecular basis of this regulation was defined by identifying two RmaH-specific DNA-binding motifs and confirming the essential role of arginine residues R79 and R87 in DNA binding. Our work elucidated a sophisticated regulatory mechanism that enabled bacteria to navigate complex and changing stressors.</p><p><strong>Importance: </strong>This study reveals how the global regulator RmaH in <i>Lactococcus lactis</i> orchestrates a critical survival trade-off, prioritizing antibiotic tolerance over acid resistance. By directly activating cell wall and membrane biosynthesis pathways, RmaH enhances defense against antimicrobials like nisin and vancomycin. Concurrently, it represses the arginine deiminase pathway, compromising the cell's ability to mitigate acid stress. This work provides a fundamental model for how bacteria dynamically allocate finite cellular resources to navigate complex, changing environments. The elucidated mechanism offers broader insights into bacterial persistence strategies and the physiological compromises underlying stress response networks.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0050225"},"PeriodicalIF":3.0,"publicationDate":"2026-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147838380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"<i>Escherichia coli</i> pathobionts and Crohn's disease: varied genetic paths leading to similar phenotypes.","authors":"Melissa Arroyo-Mendoza, Hernan Lorenzi, Gregory J Phillips, Deborah M Hinton","doi":"10.1128/jb.00016-26","DOIUrl":"https://doi.org/10.1128/jb.00016-26","url":null,"abstract":"<p><p>Crohn's disease (CD), an inflammatory bowel disease that arises from an immune attack on the gastrointestinal tract, affects roughly 1.6 million Americans. The etiology of CD and the other major irritable bowel disease, ulcerative colitis, is not known, but host genetics and immunology, the gut microbiome, and environmental factors are all thought to be involved. In addition, adherent-invasive <i>Escherichia coli</i> (AIEC) strains, which are able to adhere to and invade epithelial cells and macrophages, are frequently found to be associated with CD. Besides their adherence and invasion properties, key features that distinguish AIEC from commensal <i>E. coli</i> include increased biofilm formation, increased antibiotic resistance, and survival/replication within macrophages. However, these pathobionts lack genetic features typical of frank pathogens. Thus, the potential role AIEC plays in CD pathogenesis is not clear. The <i>E. coli</i> pathobiont LF82, isolated from the ileum of a patient with CD, has been a well-studied, prototypic AIEC. Dozens of single-nucleotide polymorphisms (SNPs) distinguish LF82 and other AIEC from commensal <i>E. coli</i>, suggesting that some of these genetic features might account for particular LF82 phenotypes. In this review, we summarize changes in the CD gut, the association of AIEC with CD, genes and SNPs associated with AIEC, and recent work connecting a specific SNP within a bacterial RNA polymerase gene to the expression of genes associated with the LF82 lifestyle.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0001626"},"PeriodicalIF":3.0,"publicationDate":"2026-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147814829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"<i>Enterococcus faecalis</i> alters antibiotic susceptibility in <i>Pseudomonas aeruginosa</i> mixed-species biofilms.","authors":"Caleb M Anderson, Yves Mattenberger, Ana Parga, Heidi Portalier, Casandra Ai Zhu Tan, Maria Esteban Henao, Patrick H Viollier, Kimberly A Kline","doi":"10.1128/jb.00548-25","DOIUrl":"https://doi.org/10.1128/jb.00548-25","url":null,"abstract":"<p><p>Bacterial infections often occur in polymicrobial biofilms where nutrient limitation and interspecies interactions can profoundly shape microbial physiology. <i>Enterococcus faecalis</i> can antagonize <i>Pseudomonas aeruginosa</i> growth under conditions of iron limitation, such as those found in the mammalian host. Here, we report that this growth antagonism reveals surviving <i>P. aeruginosa</i> cells capable of surviving antibiotic challenge, including ampicillin, cefepime, and ciprofloxacin, when grown in iron-restricted biofilms with <i>E. faecalis</i>. Transcriptomic profiling of <i>P. aeruginosa</i> revealed a distinctive response characterized by broad downregulation of biosynthetic, metabolic, and virulence pathways, alongside selective induction of membrane remodeling proteins, transport systems, and biofilm-associated genes. Induction of <i>arnT</i> in <i>P. aeruginosa</i>, required for lipid A modification, correlated with enhanced antibiotic survival to ampicillin, cefepime, and ciprofloxacin. Additionally, the diguanylate cyclase SiaD and efflux transporter MfsC in <i>P. aeruginosa</i> were implicated in decreased antibiotic susceptibility to the same antibiotics. This transcriptional response was unique to the dual stress of iron deprivation and microbial competition with <i>E. faecalis</i>, illustrating how interspecies interactions can simultaneously inhibit and protect <i>P. aeruginosa</i>, shedding light on potential persistence mechanisms in iron-limited polymicrobial environments.IMPORTANCEThis study addresses antibiotic susceptibility in <i>Pseudomonas aeruginosa</i>, a major opportunistic ESKAPE pathogen, within polymicrobial biofilms and under host-relevant iron-restricted conditions. Polymicrobial biofilm-associated infections are notoriously difficult to treat due to complex interspecies interactions and increased antibiotic resilience. We demonstrate that <i>Enterococcus faecalis</i> not only antagonizes <i>P. aeruginosa</i> growth under iron limitation but also induces a unique transcriptional profile, enhancing <i>P. aeruginosa</i> survival during antibiotic challenge. This shift involves broad transcriptional reprogramming in <i>P. aeruginosa</i>, characterized by global metabolic downregulation and activation of envelope remodeling pathways, including the <i>arn</i> operon. These findings reveal how interspecies interactions under iron stress can both suppress and protect bacterial pathogens and underscore the importance of considering community context in treatment strategies for persistent infections.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0054825"},"PeriodicalIF":3.0,"publicationDate":"2026-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147772359","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Microbe on the move: <i>Akkermansia</i> in infectious diseases and emerging roles in gynecological health.","authors":"Stephanie M Marroquin, Kelly S Doran","doi":"10.1128/jb.00491-25","DOIUrl":"10.1128/jb.00491-25","url":null,"abstract":"<p><p>The genus <i>Akkermansia</i> was first described in 2004 following the identification of <i>Akkermansia muciniphila</i>, a Gram-negative, mucin-degrading bacterium of the intestine that constitutes 1-3% of the total adult fecal content. Since the interest in <i>A. muciniphila</i> in human health has increased over the past decade, an extensive amount of research examining the impact of <i>A. muciniphila</i> on metabolic disorders, non-communicable diseases, and during infection has been published. Furthermore, a rapidly evolving area of research is the role of <i>A. muciniphila</i> in gynecological health. Many studies have shown that the presence of <i>A. muciniphila</i> may decrease the chances of negative health outcomes. Some of these protective effects include enhancement of epithelial barrier integrity and metabolism, immune modulation, and attenuation of inflammatory responses. As such, <i>A. muciniphila</i> has gained significant interest for its promising role as a next-generation probiotic. Notably, most of the <i>in vivo</i> evidence reviewed here demonstrates the probiotic potential of <i>A. muciniphila</i>. However, some findings suggest that its role is context-dependent, which may be influenced by the type of infection, diet, and microbiota composition. Herein, we review associations between <i>Akkermansia</i> species and an array of infectious diseases caused by diverse pathogen classes, including bacteria, viruses, fungi, and parasites. We also review the impact of <i>Akkermansia</i> species in gynecological conditions, particularly during pregnancy. The emerging role of <i>A. muciniphila</i> in promoting health, and in some cases disease, has important implications for understanding complex microbial-host interactions, as well as for the development of novel therapeutics.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0049125"},"PeriodicalIF":3.0,"publicationDate":"2026-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147814951","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"How mutagenesis and laboratory conditions affect the genome of the metal-resistant bacterium <i>Cupriavidus metallidurans</i> strain CH34.","authors":"Cornelia Große, Viola Dreyer, Vladislava Schulz, Grit Schleuder, Thomas A Kohl, Martin Herzberg, Dirk Dobritzsch, Matt Fuszard, Stefan Niemann, Dietrich H Nies","doi":"10.1128/jb.00121-26","DOIUrl":"https://doi.org/10.1128/jb.00121-26","url":null,"abstract":"<p><p>Insights into transition metal homeostasis of <i>Cupriavidus metallidurans</i> have relied heavily on the construction and characterization of deletion mutants. To reveal the genetic consequences of these deletions, the genomes of <i>C. metallidurans</i> strain CH34 wild type and 34 of its mutants were analyzed. The genome of <i>C. metallidurans</i> wild type remained stable when the strain was strictly kept under the appropriate conditions. Omission of selection pressure or construction of mutants, however, resulted in three different kinds of mutations. Large deletions affected genomic islands or regions in the vicinity of transposon-associated genes. Some of these large deletions could be assigned to groups of overlapping deletions associated with groups of mutants, for instance, those with deletions in metal-efflux systems. Second, single-nucleotide polymorphisms (SNPs), such as point mutations, small insertions, or deletions, with a high variant frequency, were candidates for suppressor mutations, for example, in the <i>corA1</i> or <i>yidC</i> genes. The third and novel kind of mutations comprised hypervariable regions, groups of SNPs with low variant frequencies in a small region of up to 70 base pairs that were located upstream or within genes. In the well-studied example involving the central zinc uptake regulator Zur, the hypervariable regions in the <i>zur</i> gene enabled the production of a GTP cyclohydrolase, restoring folate biosynthesis in double mutants. These data demonstrate that mutations de-stabilize the genome of <i>C. metallidurans,</i> accumulating changes that result in adaptation to the absence of the respective deleted gene, in some cases via hypervariable regions.IMPORTANCETo determine how bacteria thrive, they are often isolated from their natural environment and maintained in a laboratory. Mutations are introduced, and these derivatives are characterized phenotypically. Understanding how bacteria and their derivatives adapt to the effects of site-directed mutations, curing of plasmids, or just the laboratory environment is important. We show here that changes in the genomes of <i>Cupriavidus metallidurans</i> mutants occurred in all instances except when the wild type was maintained under selection conditions. The secondary mutations identified may be neutral, but some may affect the outcome of subsequent experiments performed to analyze the phenotypes. Our findings indicate that all generated mutations should undergo complete genomic sequencing. The information gained may deepen our understanding of bacterial life processes.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0012126"},"PeriodicalIF":3.0,"publicationDate":"2026-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147772408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Role of PsrA in physiology and virulence regulation in <i>Pseudomonas aeruginosa</i> and other bacterial species.","authors":"Selene García-Reyes, Miguel Cocotl-Yáñez, Rodolfo García-Contreras, Israel Castillo-Juárez, Bertha González-Pedrajo","doi":"10.1128/jb.00470-25","DOIUrl":"10.1128/jb.00470-25","url":null,"abstract":"<p><p><i>Pseudomonas aeruginosa</i> is an opportunistic pathogen with a complex regulatory network controlling its physiology and virulence. A key component of this network is PsrA, a TetR-family transcriptional regulator initially identified as an activator of <i>rpoS</i>. PsrA participates in multiple processes, including stress responses, fatty acid metabolism, quorum sensing, and secretion-mediated mechanisms such as the type III secretion system (T3SS). Depending on promoter context and environmental conditions, PsrA functions as both an activator and a repressor, integrating metabolic cues, particularly long-chain fatty acids, to modulate gene expression. In <i>P. aeruginosa</i>, PsrA indirectly influences quorum sensing through acyl-CoA accumulation and directly represses <i>lasR</i> and <i>rhlR</i>, while also activating the <i>exsCEBA</i> operon, required for T3SS expression during acute infection. PsrA further influences <i>rsmZ</i> expression, modulating RsmA activity and affecting pyocyanin production and biofilm-associated traits and has been linked to integrase expression in integrons. Beyond <i>P. aeruginosa</i>, PsrA orthologs and PsrA-like regulators in genera such as <i>Azotobacter</i>, <i>Legionella</i>, <i>Xanthomonas</i>, and <i>Stenotrophomonas</i> display both conserved and divergent regulatory roles, particularly in lipid metabolism and stress adaptation. These findings support PsrA as a context-dependent regulatory integrator in well-characterized T3SS-positive <i>P. aeruginosa</i> lineages, underscoring important gaps in our understanding of its regulation, evolutionary diversification, and potential relevance for future anti-virulence approaches, although direct therapeutic exploitation remains to be validated.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0047025"},"PeriodicalIF":3.0,"publicationDate":"2026-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13104628/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147433043","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Glutathione impacts Hfq condensation in nitrogen-starved <i>Escherichia coli</i>.","authors":"Harriet R Ellis, Volker Behrends, Gerald Larrouy-Maumus, Josh McQuail, Sivaramesh Wigneshweraraj","doi":"10.1128/jb.00012-26","DOIUrl":"10.1128/jb.00012-26","url":null,"abstract":"<p><p>Nitrogen (N) is essential for bacterial growth, and adaptation to N starvation involves extensive reprogramming of metabolism and gene expression. A hallmark subcellular feature in long-term N-starved <i>Escherichia coli</i> cells is the presence of biomolecular condensates of the major bacterial RNA regulator Hfq. The Hfq condensates, which accumulate gradually during N starvation, contribute to adaptation by modulating RNA metabolism and central metabolic pathways. Metabolites play central roles in stress responses, often acting as modulators of protein function to support survival and recovery. Glutathione (GSH), a universal stress protectant, has broad roles in bacterial stress adaptation, yet its function during N starvation remains unexplored. Using a GSH-deficient mutant (Δ<i>gshAB</i>), we show that GSH is required for optimal survival and recovery from prolonged N starvation. We reveal that GSH regulates the temporal dynamics of Hfq condensation and dissipation during N starvation and recovery from N starvation, respectively, via an as-yet unknown mechanism. However, the contribution of GSH to survival during and recovery from N starvation and Hfq condensation dynamics seems to be unlinked. Overall, the results point to a role for GSH in the adaptive response to N starvation, potentially extending its canonical function as a stress protectant.IMPORTANCENitrogen is a vital nutrient for bacterial growth. When nitrogen becomes scarce, bacteria must quickly adapt to survive. <i>Escherichia coli</i> forms tiny structures called Hfq condensates, which help manage genetic information flow and metabolism. Small molecules called metabolites aid bacteria in coping with stress, and one such molecule, glutathione (GSH), protects cells under various stress conditions. GSH's role during nitrogen starvation is unknown. We used an <i>E. coli</i> mutant unable to produce GSH and found that these bacteria struggle to survive and recover from nitrogen starvation. We also discovered that GSH helps control when and how Hfq condensates form and disappear. Although these two functions seem unrelated, our study highlights GSH's versatile role in helping bacteria adapt to nitrogen stress.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0001226"},"PeriodicalIF":3.0,"publicationDate":"2026-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13104617/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147498845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dual membrane-spanning anti-sigma 2 controls OMV biogenesis and colonization fitness in <i>Bacteroides thetaiotaomicron</i>.","authors":"Evan J Pardue, Tengfei Zhong, Nichollas E Scott, Biswanath Jana, Wandy Beatty, Juan C Ortiz-Marquez, Mohammed Kaplan, Clay Jackson-Litteken, Mario F Feldman","doi":"10.1128/jb.00442-25","DOIUrl":"10.1128/jb.00442-25","url":null,"abstract":"<p><p><i>Bacteroides spp</i>. are gram-negative, gut commensals that shape the enteric landscape by producing <u>o</u>uter <u>m</u>embrane <u>v</u>esicles (OMVs) that degrade dietary fibers and traffic immunomodulatory biomolecules. Understanding the mechanism behind OMV biogenesis in <i>Bacteroides spp</i>. is necessary to determine their role in the gut. Recent studies showed that mutation of <u>d</u>ual <u>m</u>embrane-spanning <u>a</u>nti-sigma factor <u>1</u> (Dma1) increased OMV production in <i>Bacteroides thetaiotaomicron</i> (<i>Bt</i>) by modulating the expression of its downstream regulon. Additional members of the Dma family have been identified, but very little is known regarding their roles in <i>Bt</i>. Here, we investigate the role of Dma2 in controlling OMV biogenesis in <i>Bt</i>. We employ biochemical and proteomic analyses to show that mutation of <i>dma2</i> increases OMV production. This induction is dependent on the expression of its cognate sigma factor, <i>das2</i>, but the precise mechanism by which <i>dma2</i> increases OMV biogenesis remains elusive. Transcriptome analyses revealed that <i>Δdma2</i> displays decreased expression of select <u>p</u>olysaccharide <u>u</u>tilization <u>l</u>oci (PULs) that primarily target host-associated glycans. Follow-up comparative proteomics showed that the PUL repertoire was most impacted in the OMV fraction. <i>In vitro</i> growth assessments confirmed that <i>Δdma2</i> exhibits delayed growth in the presence of select host-associated glycans. <i>In vivo</i> co-colonization studies in mice revealed that <i>Δdma2</i> is outcompeted by the wild-type in the gut, which indicates that Dma2 is a key determinant of colonization fitness in <i>Bt</i>. Altogether, these findings expand our knowledge of the Dma family's role in OMV biogenesis and demonstrate their importance in <i>Bacteroides</i> physiology.</p><p><strong>Importance: </strong>Dual membrane-spanning anti-sigma factors (Dma) are a novel class of regulatory proteins found solely among Bacteroidota. Previous studies demonstrated the importance of Dma1 in vesiculation, but the overall role of the Dma family in Bacteroides physiology remains poorly understood. Here, we show that Dma2 modulates vesiculation and the expression of select polysaccharide utilization loci (PULs) that target host-associated glycans <i>in vitro</i>. Mouse studies revealed that Dma2 is an important fitness determinant <i>in vivo</i> when competing against kin bacteria. This work begins characterizing the multifaceted involvement of Dma2 in OMV biogenesis, PUL regulation, and colonization fitness.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0044225"},"PeriodicalIF":3.0,"publicationDate":"2026-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13088901/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147354801","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genome-wide screen identifies novel factors for surface protein cross-wall trafficking and cell envelope homeostasis in <i>Staphylococcus aureus</i>.","authors":"Salvatore J Scaffidi, Ran Zhang, Yaosheng Jia, Wenqi Yu","doi":"10.1128/jb.00523-25","DOIUrl":"10.1128/jb.00523-25","url":null,"abstract":"<p><p>Cell-wall-anchored surface proteins are integral components of gram-positive bacterial cell envelopes. The trafficking of many surface proteins carrying a YSIRK/G-S signal peptide is synchronized with cell envelope biogenesis during cell division, whereby YSIRK proteins traffic to the septal membrane and anchor to the septal peptidoglycan (cross-wall). Previous work demonstrated that LtaS-mediated lipoteichoic acid (LTA) synthesis restricts YSIRK proteins' septal trafficking. Here, we did a comprehensive immunofluorescence microscopy screen of the entire <i>Staphylococcus aureus</i> Nebraska Transposon Mutant Library (NTML) for additional factors regulating cross-wall trafficking of staphylococcal protein A (SpA), an archetype of YSIRK proteins. We characterized nine major hits that drastically diminished SpA cross-wall localization, including <i>ypfP, ltaA</i>, <i>mprF</i>, <i>lcpB</i>, <i>lytH</i>, <i>scdA, yjbH, cbiO,</i> and <i>SAUSA300_2311,</i> along with a <i>tagO</i> mutant. Interestingly, unlike the <i>ltaS</i> mutant that delocalizes SpA at both the septal membrane and peptidoglycan layer, all the hits only delocalized SpA at the peptidoglycan layer, suggesting that these mutants affect the late-stage SpA trafficking. In addition, mutants of <i>lcpB, yjbH, cbiO,</i> and <i>2311</i> exhibited both transcriptional and spatial regulations. All the hits showed defects in cell cycle, cell morphology, and spatially dysregulated peptidoglycan (PG) synthesis. The shared phenotypes among the mutants suggest that impaired PG homeostasis and cell cycle defects are the mechanisms underlying dysregulated SpA localization. Overall, this work not only expands our understanding of YSIRK protein cross-wall trafficking but also identifies new leads that have a broader impact on the dynamics of cell cycle and cell envelope homeostasis.</p><p><strong>Importance: </strong>Surface proteins of gram-positive bacteria are key virulence factors in the human pathogen <i>Staphylococcus aureus</i>. Most surface proteins carry a YSIRK/G-S type signal peptide that promotes cross-wall trafficking and attachment to the septal cell wall during cell division. This study identified several new factors regulating this process through a comprehensive screen. The mutants identified here display dysregulated cell wall synthesis along with cell cycle defects. The results provide new insight into virulence factor trafficking and cell envelope homeostasis, which lays the foundation for developing new drug targets.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0052325"},"PeriodicalIF":3.0,"publicationDate":"2026-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13104630/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147486068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}