Journal of Bacteriology最新文献

{"title":"The DigH glycosyl hydrolase is conditionally required for daughter cell separation in <i>Escherichia coli</i>.","authors":"Joseph C Bryant, Emily J Robbs, Alongkorn Kurilung, Brittney A Dinkel, Intawat Nookaew, Matthew A Jorgenson","doi":"10.1128/jb.00068-25","DOIUrl":"10.1128/jb.00068-25","url":null,"abstract":"<p><p>The peptidoglycan (PG) cell wall is a mesh-like layer that shapes bacteria and protects against osmotically induced lysis. PG is composed of glycan strands and peptide chains that link together to form a continuous layer that surrounds the cell. PG hydrolases are required for cell wall maturation, and many are employed during cell separation. During cell division, amidases remove peptides from the glycan backbone, and the resulting denuded glycans (dnGs) are degraded by lytic transglycosylases (LTs). The gram-negative bacterium <i>Escherichia coli</i> encodes eight functional LTs (<i>mltA-G</i> and <i>slt</i>) and one putative LT (<i>rlpA</i>), and a mutant strain lacking six (Δ<i>mltACDE</i>Δ<i>slt</i>Δ<i>rlpA</i>), which we refer to as ΔLT cells, accumulates dnGs and produces short chains of cells. A morphological suppressor of the ΔLT chaining defect was isolated, and deletion analysis indicated that suppression relied primarily on increased activity of DigH, a denuded-specific hydrolase that accumulates at the midcell during cell division. Further analyses revealed that DigH is critical for cell separation in ΔLT but not wild-type cells and that dnGs accumulate even more in ΔLT cells when DigH is absent. Thus, DigH is a denuded-specific hydrolase that is conditionally required for cell separation in <i>E. coli</i>. Altogether, our findings deepen our understanding of the specific cellular function of DigH and of PG maturation in <i>E. coli</i>.</p><p><strong>Importance: </strong>Most bacteria are surrounded by an essential polymer known as the peptidoglycan cell wall. During cell division, a transient form of peptidoglycan is generated between the developing daughter cells that must be cleaved so that cells can separate. Here, we show that the DigH hydrolase is conditionally required for cell separation when this transient cell wall structure accumulates in the gram-negative bacterium <i>Escherichia coli</i>. These findings deepen our understanding of how the peptidoglycan layer is remodeled during cell division.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0006825"},"PeriodicalIF":3.0,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12288456/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144258135","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":"Bacterial evolution in the oral microbiome: the role of conjugative elements and horizontal gene transfer.","authors":"Allison J Renno, Robert C Shields, Lisa K McLellan","doi":"10.1128/jb.00066-25","DOIUrl":"10.1128/jb.00066-25","url":null,"abstract":"<p><p>As one of the most diverse bacterial populations within the human body, the oral microbiome encodes a wealth of genetic information. Horizontal gene transfer, driven by mobile genetic elements, takes advantage of this information to influence bacterial evolution and the spread of phenotypes (antibiotic resistances, virulence attributes, and metabolic capabilities) among oral microbes. Although widespread within microbial communities, fundamental aspects of the mobile elements that drive horizontal gene transfer within the oral cavity remain poorly understood. In this review, we explore what is known about the role of horizontal gene transfer in bacterial evolution within the oral microbiome and the elements that facilitate this transfer, with a specific focus on conjugative DNA transfer. Conjugative elements are found in virtually all bacterial phylogenetic clades, and some can mediate genetic exchange between distantly related organisms. This is of particular interest in the diverse microcosm of the oral cavity, specifically how it drives the evolution and virulence of dental pathogens. Finally, we highlight advances in our understanding of the unique biology within dental plaque and how these might influence our understanding of bacterial gene transfer, and thus human health and disease.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0006625"},"PeriodicalIF":3.0,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12288475/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144540336","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":"The cell wall hydrolase MltG is essential to maintain cell wall homeostasis of <i>Enterococcus faecalis</i>.","authors":"Alexis A U Knotek, Christopher J Kristich","doi":"10.1128/jb.00056-25","DOIUrl":"10.1128/jb.00056-25","url":null,"abstract":"<p><p>Infections caused by enterococci are increasingly prevalent and difficult to treat due to multidrug resistance. <i>Enterococcus faecalis</i> exhibits intrinsic resistance toward cephalosporins, which inhibit the final step of peptidoglycan (PG) synthesis. Intrinsic resistance requires multiple factors in the PG synthesis pathway and at least two cell-wall-stress signal transduction systems; however, the complete molecular mechanism of enterococcal cephalosporin resistance remains to be elucidated. MltG, a predicted PG hydrolase, is thought to process nascent strands of PG, suggesting that MltG might play an important role in enterococcal cell wall homeostasis and potentially cephalosporin resistance. Here, we demonstrate that enterococcal MltG cleaves nascent PG. An <i>E. faecalis</i> mutant lacking MltG exhibits several related phenotypes in the absence of exogenous stress: a marked growth defect, a loss of cell wall integrity, a reduction in PG synthesis, and activation of two cell-wall-stress signal transduction systems that drive elevated cephalosporin resistance. Together, these results are consistent with the model that MltG promotes proper cell wall homeostasis in <i>E. faecalis,</i> and further reveal that the enzymatic activity of MltG is not necessary for it to perform this function-instead, the LysM (putative PG-binding) domain of MltG plays the critical role. Nevertheless, the enzymatic activity of MltG does impact cephalosporin resistance, because a catalytically inactive MltG variant leads to elevated resistance. Collectively, our findings represent the first description of MltG function in <i>E. faecalis</i> and point to at least two distinct roles for MltG in PG homeostasis and cephalosporin resistance.</p><p><strong>Importance: </strong><i>Enterococcus faecalis</i> is an opportunistic pathogen that colonizes the human gut microbiome. Infections caused by <i>E. faecalis</i> are increasingly prevalent and difficult to treat due to the multidrug resistance exhibited toward common clinical antibiotics. A thorough understanding of the mechanisms used by <i>E. faecalis</i> to maintain cell wall homeostasis will serve as a foundation for future development of new therapeutics that disable enterococcal resistance to cell-wall-active antibiotics and may reveal new vulnerabilities that could be exploited by novel antimicrobials. Here, we demonstrate that the MltG peptidoglycan hydrolase is essential for enterococcal cell wall homeostasis, but that the enzymatic activity of MltG is not required for this role. Instead, the enzymatic activity of MltG impacts intrinsic resistance toward cephalosporins.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0005625"},"PeriodicalIF":3.0,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12288455/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144284480","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":"Conjugative delivery of toxin genes <i>ccdB</i> and <i>kil</i> confers synergistic killing of bacterial recipients.","authors":"Yang Grace Li, Daniel Haeusser, William Margolin, Peter J Christie","doi":"10.1128/jb.00168-25","DOIUrl":"10.1128/jb.00168-25","url":null,"abstract":"<p><p>The bacterial type IV secretion systems (T4SS) are medically problematic for their roles in the dissemination of mobile genetic elements or effector proteins, but they also have great potential for new antimicrobial therapies. Recent studies have deployed the T4SS subfamily of conjugation systems to deliver gene editing CRISPR/Cas systems to disrupt drug resistance genes or kill targeted bacterial recipients. However, the therapeutic potential of conjugative CRISPR/Cas delivery is compromised by mutations or host repair systems that diminish the efficiency with which CRISPR/Cas induces double-strand breaks in new transconjugants. Here, we compared the efficiencies of conjugation-based killing systems based on the delivery of CRISPR-Cas9 elements or toxin genes encoding the bacteriophage lambda Kil peptide or the F plasmid-encoded CcdB. <i>Escherichia coli</i> equipped with one of two efficient conjugation systems, pKM101 (IncN) or F (IncF), served as donors to mobilize plasmids carrying the cognate <i>oriT</i> sequence and one or more toxic elements. Overall, toxin gene delivery proved significantly more effective than CRISPR-Cas9 in killing of transconjugant population, but the highest levels of growth suppression of both <i>E. coli</i> and <i>Klebsiella pneumoniae</i> recipients were achieved by a combination of CRISPR-Cas9 plus one or two toxin genes. By contrast, capsule production conferred no or very slight protective effects on plasmid acquisition and killing of either species. We propose that the conjugative co-transfer of two or more toxic elements with distinct mechanisms of action has strong potential for growth suppression of targeted species in environmental or clinical settings.IMPORTANCEThe prevalence of antibiotic resistance emphasizes the need for alternative antimicrobial intervention strategies. We engineered <i>Escherichia coli</i> for conjugative transmission of plasmids encoding CRISPR-Cas9 elements or genes encoding the cell division inhibitor Kil or gyrase poisoner CcdB. Delivery of toxin genes more effectively suppressed the growth of <i>E. coli</i> recipients than CRISPR-Cas9, but the combinatorial delivery of CRISPR-Cas9 and a toxin gene or two toxin genes elicited the strongest killing effects. Capsule production by <i>E. coli</i> or <i>Klebsiella pneumoniae</i> recipient cells had no or little protective effect on plasmid acquisition or growth suppression. Our findings suggest that probiotic donor strains equipped for conjugative delivery of two or more toxic elements may prove effective as an alternative or adjunct to traditional antimicrobials.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0016825"},"PeriodicalIF":3.0,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12288468/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144553660","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":"DdiA, an XRE family transcriptional regulator, is a co-regulator of the DNA damage response in <i>Myxococcus xanthus</i>.","authors":"Jana Jung, Timo Glatter, Marco Herfurth, Lotte Søgaard-Andersen","doi":"10.1128/jb.00184-25","DOIUrl":"10.1128/jb.00184-25","url":null,"abstract":"<p><p>Repair of DNA damage is essential for genome integrity. DNA damage elicits a DNA damage response (DDR) that includes error-free and error-prone, i.e., mutagenic, repair. The SOS response is a widely conserved system in bacteria that regulates the DDR and depends on the recombinase RecA and the transcriptional repressor LexA. However, RecA/LexA-independent DDRs have been identified in several bacterial species. Here, using a whole-cell, label-free quantitative proteomics approach, we map the proteomic response in <i>Myxococcus xanthus</i> to mitomycin C treatment and the lack of LexA. In doing so, we demonstrate a LexA-independent proteomic DDR in <i>M. xanthus</i>. Using a candidate approach, we identify <u>D</u>NA <u>d</u>amage-<u>i</u>nduced protein <u>A</u> (DdiA), a transcriptional regulator of the Xenobiotic Response Element (XRE) family, and demonstrate that it is involved in regulating the abundance of a subset of the LexA-independent DDR proteins. <i>ddiA</i> is expressed heterogeneously in a subpopulation of cells in the absence of exogenous genotoxic stress and reversibly induced population wide in response to such stress. DdiA, indirectly or directly, activates the expression of <i>dnaE2</i>, which encodes the DnaE2 error-prone DNA polymerase, and inhibits the expression of <i>recX</i>, which encodes RecX, a negative regulator of RecA. Accordingly, the Δ<i>ddiA</i> mutant not only has a lower mutation frequency than the wild type but also a fitness defect, suggesting that DdiA mediates a trade-off between fitness and mutagenesis. We speculate that the DdiA-dependent response is tailored to counter replication stress, thereby preventing the induction of the complete RecA/LexA-dependent DDR in the absence of exogenous genotoxic stress.IMPORTANCEDNA damage repair is essential for genome integrity and depends on the DNA damage response (DDR). While the RecA/LexA-dependent SOS response is widely conserved in bacteria, there are also RecA/LexA-independent DDRs. Here, we identify the DNA damage-induced transcriptional regulator DdiA in <i>Myxococcus xanthus</i> and demonstrate that it regulates part of a LexA-independent DDR. DdiA activates the expression of <i>dnaE2</i>, which encodes the DnaE2 error-prone DNA polymerase, and inhibits the expression of <i>recX</i>, which encodes RecX, a negative regulator of RecA. Because the Δ<i>ddiA</i> mutant has a lower mutation frequency than the wild type but also a fitness defect, we suggest that DdiA mediates a trade-off between fitness and mutagenesis, and the DdiA-dependent DDR is specifically tailored to counter replication stress.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0018425"},"PeriodicalIF":2.7,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12288472/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144553661","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":"<i>Fusobacterium nucleatum</i>: strategies for adapting to aerobic stress.","authors":"Alexandra K McGregor, Kirsten R Wolthers","doi":"10.1128/jb.00090-25","DOIUrl":"10.1128/jb.00090-25","url":null,"abstract":"<p><p><i>Fusobacterium nucleatum</i>-a gram-negative anaerobe-is commensal to the oral cavity, where it plays an important role in the maturation of the oral biofilm. The bacterium is also an opportunistic pathogen, given its association with systemic infections and cancer progression. Although residing in largely anoxic microenvironments within the oral biofilm, <i>F. nucleatum</i> encounters oxygen (O₂) present in the circulating saliva and reactive oxygen species formed endogenously, by an activated immune system or neighboring oral commensal streptococci. This review explores the bacterium's adaptive mechanisms that enable survival under oxidative stress. We discuss how <i>F. nucleatum</i> mitigates oxidative damage and aerobic stress through common detoxifying and repair enzymes such as peroxiredoxins, methionine sulfoxide reductases, and rubrerythrin and through the activity of the recently identified multicomponent enzyme, termed butyryl-CoA oxygen oxidoreductase. Turnover by the latter enzyme enables <i>F. nucleatum</i> to exploit molecular oxygen for the conservation of energy. Additionally, we discuss how a two-component signal transduction system, ModRS, a global regulator of oxidative stress, functions in part to reprogram core metabolism to counterbalance the inactivation of a glycyl radical enzyme hypersensitive to O₂. Our findings provide new insight into how <i>F. nucleatum</i> resists fluctuating dioxygen environments, shedding light on its persistence in extraoral sites and its potential role in disease progression.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0009025"},"PeriodicalIF":2.7,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12288474/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144234198","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":"Applying the brakes to transcription: regulation of gene expression by RNA polymerase pausing.","authors":"Oshadhi T Jayasinghe, Paul Babitzke","doi":"10.1128/jb.00084-25","DOIUrl":"10.1128/jb.00084-25","url":null,"abstract":"<p><p>Transcription by RNA polymerase is punctuated by transient pausing events. Pausing provides additional time for proper RNA folding and binding of regulatory factors to the paused transcription elongation complex or the nascent RNA. Depending on the organism and the genomic context, the general transcription elongation factors NusA and NusG stimulate or suppress pausing. Both <i>Escherichia coli</i> and <i>Bacillus subtilis</i> NusA stimulate pausing <i>in vitro</i>, while the genome-wide role of NusA on pausing has only been examined in <i>B. subtilis</i>. NusG-dependent pausing was identified throughout the <i>B. subtilis</i> genome, and in several instances, these pauses were shown to regulate the expression of the downstream gene(s). This pro-pausing activity was also observed for <i>Mycobacterium tuberculosis</i> NusG. In contrast, <i>E. coli</i> NusG functions as an anti-pausing factor by suppressing pausing throughout the genome. These differences in the function of NusG highlight the importance of studying fundamental processes in a variety of bacterial species. This review will highlight recent advances gained by the ability to identify pauses genome-wide that are either stimulated or suppressed by these two conserved transcription elongation factors.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0008425"},"PeriodicalIF":2.7,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12288461/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144234199","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":"\"Pupdates\" on proteasomal degradation in bacteria.","authors":"Shoshanna C Kahne, K Heran Darwin","doi":"10.1128/jb.00111-25","DOIUrl":"10.1128/jb.00111-25","url":null,"abstract":"<p><p>Proteasomes are multi-subunit proteases found in all domains of life. The central components of proteasomal degradation are conserved, but how proteins are targeted to proteasomes diverges significantly. Despite the vast amount of information learned about how proteasomal degradation is regulated in eukaryotes, much less is known about the regulation of proteasome activity in bacteria. In this minireview, we highlight recent findings revealing how and when specific proteins are targeted to bacterial proteasomes, with a focus on ATP-dependent proteolysis.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0011125"},"PeriodicalIF":3.0,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12288473/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144225575","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":"Unexpected contribution of the Fak system and the thioesterase TesE to the growth and membrane physiology of <i>Enterococcus faecalis</i>.","authors":"R D Johnston, T A Getty, B M Woodall, S Maharjan, N L Arnold, W B Seaton, M Stevenson, S R Campagna, E M Fozo","doi":"10.1128/jb.00121-25","DOIUrl":"10.1128/jb.00121-25","url":null,"abstract":"<p><p><i>Enterococcus faecalis</i> is a native of the intestine and a hospital-acquired pathogen that uses host fatty acids to form its membrane. We investigated the utilization of exogenous fatty acids via the fatty acid kinase (Fak) system to understand the varied impacts fatty acids have on physiology. FakB proteins bind fatty acids, and FakA then phosphorylates them for lipid synthesis. Network analysis indicated that two of the four FakB proteins of <i>E. faecalis</i> OG1RF cluster with described proteins of <i>Staphylococcus aureus</i> and <i>Streptococcus pneumoniae</i> (FakB1, FakB2). However, two additional <i>E. faecalis</i> FakB proteins clustered separately and distinctly from characterized proteins; these were subsequently denoted as FakB4 and FakB5. A strain deleted for three of the four genes (<i>ΔfakB1,2,5</i> strain) had severe morphological defects when grown in rich media. Deletion of all four <i>fakB</i>-encoding genes was not possible unless a thioesterase encoding gene, <i>tesE</i>, was also deleted (<i>Δquint</i> strain). The <i>Δquint</i> strain behaved similarly to wild-type OG1RF in rich media, indicating that the combination of free fatty acids from the growth environment and those liberated via TesE was detrimental to the <i>ΔfakB1,2,5</i> strain. The <i>Δquint</i> strain grew unimpeded in saturated fatty acids that are normally toxic to <i>E. faecalis,</i> indicating that incorporation of these fatty acids into phospholipids mediates their toxicity. While saturated fatty acids reduced the membrane fluidity of wild-type OG1RF, they had no impact on the <i>Δquint</i> strain. Our combined data support that the Fak system in <i>E. faecalis</i> plays a critical role in maintaining membrane fluidity and driving enterococcal physiology.IMPORTANCEBacteria living within humans encounter a variety of fatty acids that they can use to synthesize their own cellular material. However, different fatty acids can have a variety of effects on the same bacterial species. Within, we examined how <i>Enterococcus faecalis</i>, which naturally lives in human intestines but can also cause disease, uses fatty acids from its environment. We discovered unexpectedly that fatty acid binding proteins contribute to many aspects controlling bacterial growth, shape, and behavior.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0012125"},"PeriodicalIF":3.0,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12288450/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144528104","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":"Genetic analysis of flagellar-mediated surface sensing by <i>Pseudomonas aeruginosa</i> PA14.","authors":"Sherry L Kuchma, C J Geiger, Shanice S Webster, Yu Fu, Robert Montoya, George A O'Toole","doi":"10.1128/jb.00520-24","DOIUrl":"10.1128/jb.00520-24","url":null,"abstract":"<p><p>Surface sensing is a key aspect of the early stage of biofilm formation. For <i>Pseudomonas aeruginosa</i> PA14, the type IV pili (T4P), the T4P alignment complex, and PilY1 were shown to play a key role in c-di-GMP signaling upon surface contact. The role of the flagellar machinery in surface sensing is less well understood for <i>P. aeruginosa</i>. Here, we show, consistent with findings from other groups, that a mutation in the gene encoding the flagellar hook protein (Δ<i>flgK</i>) or flagellin (Δ<i>fliC</i>) results in a strain that overproduces the Pel exopolysaccharide (EPS) with a concomitant increase in c-di-GMP levels. We use a candidate gene approach and genetic screens, combined with phenotypic assays, to identify key roles for the MotAB and MotCD stators and the FliG protein, a component of the flagellar switch complex, in stimulating the surface-dependent, increased c-di-GMP level noted for these flagellar mutants. These findings are consistent with previous studies showing a role for the stators in surface sensing. We also show that mutations in the genes coding for the DGCs SadC and RoeA, as well as SadB, a protein involved in early surface colonization, abrogate the increased c-d-GMP-related phenotypes of the Δ<i>flgK</i> mutant. Together, these data indicate that bacteria monitor the status of flagellar synthesis and function during surface sensing as a mechanism to trigger the biofilm program.</p><p><strong>Importance: </strong>Understanding how the flagellum contributes to surface sensing for <i>P. aeruginosa</i> is key to elucidating the mechanisms of biofilm initiation by this important opportunistic pathogen. Here, we take advantage of the observation that mutations in the flagellar hook protein or flagellin enhance surface sensing. We exploit this phenotype to identify key players in this signaling pathway, a critical first step in understanding the mechanistic basis of flagellar-mediated surface sensing. Our findings establish a framework for the future study of flagellar-based surface sensing.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0052024"},"PeriodicalIF":3.0,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12288467/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144225576","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}