{"title":"Characterization of galactose catabolic pathways in <i>Streptococcus agalactiae</i> and identification of a major galactose: phosphotransferase importer.","authors":"Aurelia Hiron, Morgane Melet, Capucine Guerry, Ilona Dubois, Vanessa Rong, Philippe Gilot","doi":"10.1128/jb.00155-24","DOIUrl":"10.1128/jb.00155-24","url":null,"abstract":"<p><p>We identified and characterized genomic regions of <i>Streptococcus agalactiae</i> that are involved in the Leloir and the tagatose-6-phosphate pathways for D-galactose catabolism. The accumulation of mutations in genes coding the Leloir pathway and the absence of these genes in a significant proportion of the strains suggest that this pathway may no longer be necessary for <i>S. agalactiae</i> and is heading toward extinction. In contrast, a genomic region containing genes coding for intermediates of the tagatose-6-phosphate pathway, a Gat family PTS transporter, and a DeoR/GlpR family regulator is present in the vast majority of strains. By deleting genes that code for intermediates of each of these two pathways in three selected strains, we demonstrated that the tagatose-6-phosphate pathway is their sole route for galactose catabolism. Furthermore, we showed that the Gat family PTS transporter acts as the primary importer of galactose in <i>S. agalactiae</i>. Finally, we proved that the DeoR/GlpR family regulator is a repressor of the tagatose-6-phosphate pathway and that galactose triggers the induction of this biochemical mechanism.IMPORTANCE<i>S. agalactiae</i>, a significant pathogen for both humans and animals, encounters galactose and galactosylated components within its various ecological niches. We highlighted the capability of this bacterium to metabolize D-galactose and showed the role of the tagatose-6-phosphate pathway and of a PTS importer in this biochemical process. Since <i>S. agalactiae</i> relies on carbohydrate fermentation for energy production, its ability to uptake and metabolize D-galactose could enhance its persistence and its competitiveness within the microbiome.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0015524"},"PeriodicalIF":2.7,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11500514/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142287952","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}
Delayna L Warrell, Tiffany M Zarrella, Christopher Machalek, Anupama Khare
{"title":"Interspecies surfactants serve as public goods enabling surface motility in <i>Pseudomonas aeruginosa</i>.","authors":"Delayna L Warrell, Tiffany M Zarrella, Christopher Machalek, Anupama Khare","doi":"10.1128/jb.00281-24","DOIUrl":"10.1128/jb.00281-24","url":null,"abstract":"<p><p>In most natural environments, bacteria live in polymicrobial communities where secreted molecules from neighboring species alter bacterial behaviors, including motility, but such interactions are understudied. <i>Pseudomonas aeruginosa</i> is a motile opportunistic pathogen that exists in diverse multispecies environments, such as the soil, and is frequently found in human wound and respiratory tract co-infections with other bacteria, including <i>Staphylococcus aureus</i>. Here, we show that <i>P. aeruginosa</i> can co-opt secreted surfactants from other species for flagellar-based surface motility. We found that exogenous surfactants from <i>S. aureus</i>, other bacteria, and interkingdom species enabled <i>P. aeruginosa</i> to switch from swarming to an alternative surface spreading motility on semi-solid surfaces and allowed for the emergence of surface motility on hard agar where <i>P. aeruginosa</i> was otherwise unable to move. Although active flagellar function was required for surface spreading, known motility regulators were not essential, indicating that surface spreading may be regulated by an as yet unknown mechanism. This motility was distinct from the response of most other motile bacterial species in the presence of exogenous surfactants. Mutant analysis indicated that this <i>P. aeruginosa</i> motility was similar to a previously described mucin-based motility, \"surfing,\" albeit with divergent regulation. Thus, our study demonstrates that secreted surfactants from the host as well as neighboring bacterial and interkingdom species act as public goods facilitating <i>P. aeruginosa</i> flagella-mediated surfing-like surface motility, thereby allowing it to access different environmental niches.</p><p><strong>Importance: </strong>Bacterial motility is an important determinant of bacterial fitness and pathogenesis, allowing expansion and invasion to access nutrients and adapt to new environments. Here, we demonstrate that secreted surfactants from a variety of foreign species, including other bacterial species, infection hosts, fungi, and plants, facilitate surface spreading motility in the opportunistic pathogen <i>Pseudomonas aeruginosa</i> that is distinct from established motility phenotypes. This response to foreign surfactants also occurs in <i>Pseudomonas putida</i>, but not in more distantly related bacterial species. Our systematic characterization of surfactant-based surface spreading shows that these interspecies surfactants serve as public goods to enable <i>P. aeruginosa</i> to move and explore environmental conditions when it would be otherwise immotile.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0028124"},"PeriodicalIF":2.7,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11500613/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142132848","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}
Safiya Alvi, V Denise Mondelo, Jacqueline Boyle, Amanda Buck, Justin Gejo, Molly Mason, Shriya Matta, Abigail Sheridan, Mark A B Kreutzberger, Edward H Egelman, Anna McLoon
{"title":"Flagellar point mutation causes social aggregation in laboratory-adapted <i>Bacillus subtilis</i> under conditions that promote swimming.","authors":"Safiya Alvi, V Denise Mondelo, Jacqueline Boyle, Amanda Buck, Justin Gejo, Molly Mason, Shriya Matta, Abigail Sheridan, Mark A B Kreutzberger, Edward H Egelman, Anna McLoon","doi":"10.1128/jb.00199-24","DOIUrl":"10.1128/jb.00199-24","url":null,"abstract":"<p><p>Motility allows microbes to explore and maximize success in their environment; however, many laboratory bacterial strains have a reduced or altered capacity for motility. Swimming motility in <i>Bacillus subtilis</i> depends on peritrichous flagella and is carried out individually as cells move by biased random walks toward attractants. Previously, we adapted <i>Bacillus subtilis</i> strain 3610 to the laboratory for 300 generations in lysogeny broth (LB) batch culture and isolated lab-adapted strains. Strain SH2 is motility-defective and in broth culture forms large, frequently spherical aggregates of cells. A single point mutation in the flagellin gene <i>hag</i> that causes amino acid 259 to switch from A to T is necessary and sufficient to cause these social cell aggregates, and aggregation occurs between flagellated cells bearing this point mutation regardless of the strain background. Cells associate when bearing this mutation, but flagellar rotation is needed to pull associating cells into spherical aggregates. Using electron microscopy, we are able to show that the SH2 flagellar filament has limited polymorphism when compared to other flagellar structures. This limited polymorphism hinders the flagellum's ability to function as a motility apparatus but appears to alter its function to that of cell aggregation/adhesion. We speculate that the genotype-specific aggregation of cells producing Hag<sup>A259T</sup> flagella could have increased representation in a batch-culture experiment by allowing similar cells to go through a transfer together and also that this mutation could serve as an early step to evolve sociality in the natural world.IMPORTANCEThe first life forms on this planet were prokaryotic, and the earliest environments were aquatic, and from these relatively simple starting conditions, complex communities of microbes and ultimately multicellular organisms were able to evolve. Usually, motile cells in aqueous environments swim as individuals but become social by giving up motility and secreting extracellular substances to become a biofilm. Here, we identify a single point mutation in the flagellum that is sufficient to allow cells containing this mutation to specifically form large, suspended groups of cells. The specific change in the flagellar filament protein subunits causes a unique change in the flagellar structure. This could represent a distinct way for closely related cells to associate as an early precursor to sociality.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0019924"},"PeriodicalIF":2.7,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11500573/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142154076","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}
Yutian Peng, John G Moffat, Cory DuPai, Eric M Kofoed, Elizabeth Skippington, Zora Modrusan, Susan L Gloor, Kevin Clark, Yiming Xu, Shuxuan Li, Liuxi Chen, Xingrong Liu, Ping Wu, Seth F Harris, Shumei Wang, Terry D Crawford, Chun Sing Li, Zhiguo Liu, John Wai, Man-Wah Tan
{"title":"Differential effects of inosine monophosphate dehydrogenase (IMPDH/GuaB) inhibition in <i>Acinetobacter baumannii</i> and <i>Escherichia coli</i>.","authors":"Yutian Peng, John G Moffat, Cory DuPai, Eric M Kofoed, Elizabeth Skippington, Zora Modrusan, Susan L Gloor, Kevin Clark, Yiming Xu, Shuxuan Li, Liuxi Chen, Xingrong Liu, Ping Wu, Seth F Harris, Shumei Wang, Terry D Crawford, Chun Sing Li, Zhiguo Liu, John Wai, Man-Wah Tan","doi":"10.1128/jb.00102-24","DOIUrl":"10.1128/jb.00102-24","url":null,"abstract":"<p><p>Inosine 5'-monophosphate dehydrogenase (IMPDH), known as GuaB in bacteria, catalyzes the rate-limiting step in <i>de novo</i> guanine biosynthesis and is conserved from humans to bacteria. We developed a series of potent inhibitors that selectively target GuaB over its human homolog. Here, we show that these GuaB inhibitors are bactericidal, generate phenotypic signatures that are distinct from other antibiotics, and elicit different time-kill kinetics and regulatory responses in two important Gram-negative pathogens: <i>Acinetobacter baumannii</i> and <i>Escherichia coli</i>. Specifically, the GuaB inhibitor G6 rapidly kills <i>A. baumannii</i> but only kills <i>E. coli</i> after 24 h. After exposure to G6, the expression of genes involved in purine biosynthesis and stress responses change in opposite directions while siderophore biosynthesis is downregulated in both species. Our results suggest that different species respond to GuaB inhibition using distinct regulatory programs and possibly explain the different bactericidal kinetics upon GuaB inhibition. The comparison highlights opportunities for developing GuaB inhibitors as novel antibiotics.IMPORTANCE<i>A. baumannii</i> is a priority bacterial pathogen for which development of new antibiotics is urgently needed due to the emergence of multidrug resistance. We recently developed a series of specific inhibitors against GuaB, a bacterial inosine 5'-monophosphate dehydrogenase, and achieved sub-micromolar minimum inhibitory concentrations against <i>A. baumannii</i>. GuaB catalyzes the rate-limiting step of <i>de novo</i> guanine biosynthesis and is highly conserved across bacterial pathogens. This study shows that inhibition of GuaB induced a bacterial morphological profile distinct from that of other classes of antibiotics, highlighting a novel mechanism of action. Moreover, our transcriptomic analysis showed that regulation of <i>de novo</i> purine biosynthesis and stress responses of <i>A. baumannii</i> upon GuaB inhibition differed significantly from that of <i>E. coli</i>.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0010224"},"PeriodicalIF":2.7,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11500612/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142132833","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":"Overexpression of diglucosyldiacylglycerol synthase leads to daptomycin resistance in <i>Bacillus subtilis</i>.","authors":"Ryogo Yamamoto, Kazuya Ishikawa, Yusuke Miyoshi, Kazuyuki Furuta, Shin-Ichi Miyoshi, Chikara Kaito","doi":"10.1128/jb.00307-24","DOIUrl":"10.1128/jb.00307-24","url":null,"abstract":"<p><p>The lipopeptide antibiotic daptomycin exhibits bactericidal activity against Gram-positive bacteria by forming a complex with phosphatidylglycerol (PG) and lipid II in the cell membrane, causing membrane perforation. With the emergence of daptomycin-resistant bacteria, understanding the mechanisms of bacterial resistance to daptomycin has gained great importance. In this study, we aimed to identify the genetic factors contributing to daptomycin resistance in <i>Bacillus subtilis</i>, a model Gram-positive bacterium. Our findings demonstrated that overexpression of <i>ugtP</i>, which encodes diglucosyldiacylglycerol synthase, induces daptomycin resistance in <i>B. subtilis</i>. Specifically, overexpression of <i>ugtP</i> resulted in increased levels of diglucosyldiacylglycerol (Glc<sub>2</sub>DAG) and decreased levels of acidic phospholipids cardiolipin and PG, as well as the basic phospholipid lysylphosphatidylglycerol. However, <i>ugtP</i> overexpression did not alter the cell surface charge and the susceptibility to the cationic antimicrobial peptide nisin or the cationic surfactant hexadecyltrimethylammonium bromide. Furthermore, by serial passaging in the presence of daptomycin, we obtained daptomycin-resistant mutants carrying <i>ugtP</i> mutations. These mutants showed increased levels of Glc<sub>2</sub>DAG and a >4-fold increase in the minimum inhibitory concentration of daptomycin. These results suggest that increased Glc<sub>2</sub>DAG levels, driven by <i>ugtP</i> overexpression, modify the phospholipid composition and confer daptomycin resistance in <i>B. subtilis</i> without altering the cell surface charge of the bacteria.IMPORTANCEDaptomycin is one of the last-resort drugs for the treatment of methicillin-resistant <i>Staphylococcus aureus</i> infections, and the emergence of daptomycin-resistant bacteria has become a major concern. Understanding the mechanism of daptomycin resistance is important for establishing clinical countermeasures against daptomycin-resistant bacteria. In the present study, we found that overexpression of <i>ugtP</i>, which encodes diglucosyldiacylglycerol synthase, induces daptomycin resistance in <i>B. subtilis</i>, a model Gram-positive bacteria. The overexpression of <i>UgtP</i> increased diglucosyldiacylglycerol levels, resulting in altered phospholipid composition and daptomycin resistance. These findings are important for establishing clinical strategies against daptomycin-resistant bacteria, including their detection and management.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0030724"},"PeriodicalIF":2.7,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11500525/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142140172","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}
Zachary A Taylor, Ping Chen, Payam Noeparvar, Danniel N Pham, Alejandro R Walker, Todd Kitten, Lin Zeng
{"title":"Glycerol metabolism contributes to competition by oral streptococci through production of hydrogen peroxide.","authors":"Zachary A Taylor, Ping Chen, Payam Noeparvar, Danniel N Pham, Alejandro R Walker, Todd Kitten, Lin Zeng","doi":"10.1128/jb.00227-24","DOIUrl":"10.1128/jb.00227-24","url":null,"abstract":"<p><p>As a biological byproduct from both humans and microbes, glycerol's contribution to microbial homeostasis in the oral cavity remains understudied. In this study, we examined glycerol metabolism by <i>Streptococcus sanguinis,</i> a commensal associated with oral health. Genetic mutants of glucose-PTS enzyme II (<i>manL</i>), glycerol metabolism (<i>glp</i> and <i>dha</i> pathways), and transcriptional regulators were characterized with regard to glycerol catabolism, growth, production of hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>), transcription, and competition with <i>Streptococcus mutans</i>. Biochemical assays identified the <i>glp</i> pathway as a novel source for H<sub>2</sub>O<sub>2</sub> production by <i>S. sanguinis</i> that is independent of pyruvate oxidase (SpxB). Genetic analysis indicated that the <i>glp</i> pathway requires glycerol and a transcriptional regulator, GlpR, for expression and is negatively regulated by PTS, but not the catabolite control protein, CcpA. Conversely, deletion of either <i>manL</i> or <i>ccpA</i> increased the expression of <i>spxB</i> and a second, H<sub>2</sub>O<sub>2</sub>-non-producing glycerol metabolic pathway (<i>dha</i>), indicative of a mode of regulation consistent with conventional carbon catabolite repression (CCR). In a plate-based antagonism assay and competition assays performed with planktonic and biofilm-grown cells, glycerol greatly benefited the competitive fitness of <i>S. sanguinis</i> against <i>S. mutans</i>. The <i>glp</i> pathway appears to be conserved in several commensal streptococci and actively expressed in caries-free plaque samples. Our study suggests that glycerol metabolism plays a more significant role in the ecology of the oral cavity than previously understood. Commensal streptococci, though not able to use glycerol as a sole carbohydrate source for growth, benefit from the catabolism of glycerol through production of both ATP and H<sub>2</sub>O<sub>2</sub>.</p><p><strong>Importance: </strong>Glycerol is an abundant carbohydrate in the oral cavity. However, little is understood regarding the metabolism of glycerol by commensal streptococci, some of the most abundant oral bacteria. This was in part because most streptococci cannot grow on glycerol as the sole carbon source. In this study, we show that <i>Streptococcus sanguinis</i>, a commensal associated with dental health, can degrade glycerol for persistence and competition through two pathways, one of which generates hydrogen peroxide at levels capable of inhibiting <i>Streptococcus mutans</i>. Preliminary studies suggest that several additional commensal streptococci are also able to catabolize glycerol, and glycerol-related genes are actively expressed in human dental plaque samples. Our findings reveal the potential of glycerol to significantly impact microbial homeostasis, which warrants further exploration.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0022724"},"PeriodicalIF":2.7,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11411925/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142017521","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}
Jingjun Lin, Sook Yin Chong, Myung Whan Oh, Shi Qian Lew, Luchang Zhu, Xuejin Zhang, William H Witola, Gee W Lau
{"title":"Signal recognition particle RNA is critical for genetic competence and virulence of <i>Streptococcus pneumoniae</i>.","authors":"Jingjun Lin, Sook Yin Chong, Myung Whan Oh, Shi Qian Lew, Luchang Zhu, Xuejin Zhang, William H Witola, Gee W Lau","doi":"10.1128/jb.00004-24","DOIUrl":"10.1128/jb.00004-24","url":null,"abstract":"<p><p><i>Streptococcus pneumoniae</i> (pneumococcus) causes a wide range of important human infectious diseases, including pneumonia, pneumonia-derived sepsis, otitis media, and meningitis. Pneumococcus produces numerous secreted proteins that are critical for normal physiology and pathogenesis. The membrane targeting and translocation of these secreted proteins are partly mediated by the signal recognition particle (SRP) complex, which consists of 4.5S small cytoplasmic RNA (ScRNA), and the Ffh, and FtsY proteins. Here, we report that pneumococcal ∆<i>scRNA</i>, ∆<i>ffh,</i> and ∆<i>ftsY</i> mutants were significantly impaired in competence induction, competence pili production, exogenous DNA uptake, and genetic transformation. Also, the ∆<i>scRNA</i> mutant was significantly attenuated in the mouse models of bacteremia and pneumonia. Interestingly, unlike the ∆<i>scRNA</i>, both ∆<i>ffh</i> and ∆<i>ftsY</i> mutants had growth defects on Todd-Hewitt Agar, which were alleviated by the provision of free amino acids or serum. Differences in nutritional requirements between ∆<i>ffh</i> and ∆<i>ftsY</i> vs ∆<i>scRNA</i> suggest that Ffh and FtsY may be partially functional in the absence of ScRNA. Finally, the insertase YidC2, which could functionally rescue some SRP mutations in other streptococcal species, was not essential for pneumococcal genetic transformation. Collectively, these results indicate that ScRNA is crucial for the successful development of genetic competence and virulence in pneumococcus.</p><p><strong>Importance: </strong><i>Streptococcus pneumoniae</i> (pneumococcus) causes multiple important infectious diseases in humans. The signal recognition particle (SRP) complex, which comprised 4.5S small cytoplasmic RNA (ScRNA), and the Ffh and FtsY proteins, mediates membrane targeting and translocation of secreted proteins in all organisms. However, the role of SRP and ScRNA has not been characterized during the induction of the competence system for genetic transformation and virulence in pneumococcus. By using a combination of genetic, biochemical, proteomic, and imaging approaches, we demonstrated that the SRP complex plays a significant role in membrane targeting of competence system-regulated effectors important for genetic transformation, virulence during bacteremia and pneumonia infections, and nutritional acquisition.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0000424"},"PeriodicalIF":2.7,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11412328/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142017523","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}
Brandon Robin, Amélie Dewitte, Véronique Alaimo, Cecile Lecoeur, François Pierre, Gabriel Billon, Florent Sebbane, Sébastien Bontemps-Gallo
{"title":"The CpxAR signaling system confers a fitness advantage for flea gut colonization by the plague bacillus.","authors":"Brandon Robin, Amélie Dewitte, Véronique Alaimo, Cecile Lecoeur, François Pierre, Gabriel Billon, Florent Sebbane, Sébastien Bontemps-Gallo","doi":"10.1128/jb.00173-24","DOIUrl":"10.1128/jb.00173-24","url":null,"abstract":"<p><p>The adaptation of <i>Yersinia pestis</i>, the flea-borne plague agent, to fluctuating environmental conditions is essential for the successful colonization of the flea vector. A previous comparative transcriptomic analysis showed that the Cpx pathway of <i>Y. pestis</i> is up-regulated in infected fleas. The CpxAR two-component system is a component of the envelope stress response and is critical for maintaining the integrity of the cell. Here, a phenotypic screening revealed a survival defect of the <i>cpxAR</i> mutant to oxidative stress and copper. The measured copper concentration in the digestive tract contents of fed fleas increased fourfold during the digestive process. By direct analysis of phosphorylation of CpxR by a Phos-Tag gel approach, we demonstrated that biologically relevant concentrations of copper triggered the system. Then, a competitive challenge highlighted the role of the CpxAR system in bacterial fitness during flea infection. Lastly, an <i>in vitro</i> sequential exposure to copper and then H<sub>2</sub>O<sub>2</sub> to mimic the flea suggests a model in which, within the insect digestive tract, the CpxAR system would be triggered by copper, establishing an oxidative stress response.</p><p><strong>Importance: </strong>The bacterium <i>Yersinia pestis</i> is the agent of flea-borne plague. Our knowledge of the mechanisms used by the plague bacillus to infect the flea vector is limited. The up-regulation of the envelope stress response under the control of the Cpx signaling pathway was previously shown in a transcriptomic study. Here, our <i>in vivo</i> and <i>in vitro</i> approaches suggest a model in which <i>Y. pestis</i> uses the CpxAR phosphorelay system to sense and respond to the copper present in the flea gut, thereby optimizing the flea gut colonization. In other words, the system is essential for bacterial fitness in the flea.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0017324"},"PeriodicalIF":2.7,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11411919/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141999929","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":"Hitchhiker's Guide to <i>Borrelia burgdorferi</i>.","authors":"Jeffrey S Bourgeois, Linden T Hu","doi":"10.1128/jb.00116-24","DOIUrl":"10.1128/jb.00116-24","url":null,"abstract":"<p><p>Don't Panic. In the nearly 50 years since the discovery of Lyme disease, <i>Borrelia burgdorferi</i> has emerged as an unlikely workhorse of microbiology. Interest in studying host-pathogen interactions fueled significant progress in making the fastidious microbe approachable in laboratory settings, including the development of culture methods, animal models, and genetic tools. By developing these systems, insight has been gained into how the microbe is able to survive its enzootic cycle and cause human disease. Here, we discuss the discovery of <i>B. burgdorferi</i> and its development as a model organism before diving into the critical lessons we have learned about <i>B. burgdorferi</i> biology at pivotal stages of its lifecycle: gene expression changes during the tick blood meal, colonization of a new vertebrate host, and developing a long-lasting infection in that vertebrate until a new tick feeds. Our goal is to highlight the advancements that have facilitated <i>B. burgdorferi</i> research and identify gaps in our current understanding of the microbe.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0011624"},"PeriodicalIF":2.7,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11411949/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141975662","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":"Determinants of maturation of the <i>Staphylococcus aureus</i> autoinducing peptide.","authors":"Liwei Fang, Chance Cosgriff, Francis Alonzo","doi":"10.1128/jb.00195-24","DOIUrl":"10.1128/jb.00195-24","url":null,"abstract":"<p><p>The <u>a</u>ccessory <u>g</u>ene <u>r</u>egulatory (Agr) system is required for virulence factor gene expression and pathogenesis of <i>Staphylococcus aureus</i>. The Agr system is activated in response to the accumulation of a cyclic autoinducing peptide (AIP), which is matured and secreted by the bacterium. The precursor of AIP, AgrD, consists of the AIP flanked by an N-terminal [Formula: see text]-helical Leader and a charged C-terminal tail. AgrD is matured to AIP by the action of two proteases, AgrB and MroQ. AgrB cleaves the C-terminal tail and promotes the formation of a thiolactone ring, whereas MroQ cleaves the N-terminal Leader in a manner that depends on the four-amino acid linker immediately following a conserved IG helix breaker motif. However, the attributes of AgrD that dictate the sequence of events in peptide maturation are not fully defined. Here, we used engineered AgrD peptide intermediates to ascertain the sufficiency of MroQ for N-terminal peptide cleavage, peptide export, and generation of mature AIP. We found that MroQ promotes the removal of the N-terminal Leader peptide from both linear and cyclic peptide intermediates, while peptide cyclization remained essential for signaling. The expression of the Leader peptide in isolation was sufficient for MroQ-dependent cleavage proximal to the four-amino-acid linker. In addition, active site mutations within AgrB destabilized full-length AgrD and thiolactone-containing intermediates and prevented the release of the Leader peptide. Altogether, our data support a tandem peptide maturation event involving both MroQ and AgrB that appears to couple protease activity and export of bioactive AIP.IMPORTANCEThe <u>a</u>ccessory <u>g</u>ene <u>r</u>egulatory (Agr) system is important for <i>S. aureus</i> pathogenesis. Activation of the Agr system requires recognition of a cyclic peptide pheromone, which must be fully matured to exert its biological activity. The complete events in cyclic peptide maturation and export from the bacterial cell remain to be fully defined. We and others recently discovered that the membrane peptidase MroQ is required for pheromone maturation. This study builds off the identification of MroQ and considers the attributes of the pheromone pro-peptide that are required for MroQ-mediated processing as well as uncovers features important for peptide stability and export. Overall, the findings in this study have implications for understanding bacterial pheromone maturation and virulence.</p>","PeriodicalId":15107,"journal":{"name":"Journal of Bacteriology","volume":" ","pages":"e0019524"},"PeriodicalIF":2.7,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11412329/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142035929","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}