mBio最新文献

{"title":"Giant transposons promote strain heterogeneity in a major fungal pathogen.","authors":"Emile Gluck-Thaler, Adrian Forsythe, Charles Puerner, Cecilia Gutierrez-Perez, Jason E Stajich, Daniel Croll, Robert A Cramer, Aaron A Vogan","doi":"10.1128/mbio.01092-25","DOIUrl":"https://doi.org/10.1128/mbio.01092-25","url":null,"abstract":"<p><p>Fungal infections are difficult to prevent and treat in large part due to strain heterogeneity, which confounds diagnostic predictability. Yet, the genetic mechanisms driving strain-to-strain variation remain poorly understood. Here, we determined the extent to which <i>Starships</i>-giant transposons capable of mobilizing numerous fungal genes-generate genetic and phenotypic variability in the opportunistic human pathogen <i>Aspergillus fumigatus</i>. We analyzed 519 diverse strains, including 11 newly sequenced with long-read technology and multiple isolates of the same reference strain, to reveal 20 distinct <i>Starships</i> that are generating genomic heterogeneity over timescales relevant for experimental reproducibility. <i>Starship</i>-mobilized genes encode diverse functions, including known biofilm-related virulence factors and biosynthetic gene clusters, and many are differentially expressed during infection and antifungal exposure in a strain-specific manner. These findings support a new model of fungal evolution wherein <i>Starships</i> help generate variation in genome structure, gene content, and expression among fungal strains. Together, our results demonstrate that <i>Starships</i> are a previously hidden mechanism generating genotypic and, in turn, phenotypic heterogeneity in a major human fungal pathogen.IMPORTANCENo \"one size fits all\" option exists for treating fungal infections in large part due to genetic and phenotypic variability among strains. Accounting for strain heterogeneity is thus fundamental for developing efficacious treatments and strategies for safeguarding human health. Here, we report significant progress toward achieving this goal by uncovering a previously hidden mechanism generating heterogeneity in the human fungal pathogen <i>Aspergillus fumigatus</i>: giant transposons, called <i>Starships</i>, that span dozens of kilobases and mobilize fungal genes as cargo. By conducting a systematic investigation of these unusual transposons in a single fungal species, we demonstrate their contributions to population-level variation at the genome, pangenome, and transcriptome levels. The <i>Starship</i> compendium we develop will not only help predict variation introduced by these elements in laboratory experiments but will serve as a foundational resource for determining how <i>Starships</i> impact clinically relevant phenotypes, such as antifungal resistance and pathogenicity.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0109225"},"PeriodicalIF":5.1,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143980933","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ecologically expanding the One Health framework to unify the microbiome sciences.","authors":"Nichole Ginnan, Sharifa G Crandall, Madangchanok Imchen, Francisco Dini-Andreote, Tim I Miyashiro, Vishal Singh, Erika Ganda, Seth R Bordenstein","doi":"10.1128/mbio.03147-24","DOIUrl":"https://doi.org/10.1128/mbio.03147-24","url":null,"abstract":"<p><p>The One Health framework, traditionally focused on microbial threats, needs a bold expansion to include the full breadth of microbial diversity-from pathogenic to beneficial-within its ecological and evolutionary context. By shifting focus from disease surveillance to microbial stewardship, an integrative One Health microbiome science approach breaks down traditional silos in microbiome research, accelerating integrative and comparative science to uncover foundational insights into microbial community assembly, stability, and resilience. Ultimately, this will help unlock the full potential of microbiomes to enhance global health and sustainably manage ecosystems.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0314724"},"PeriodicalIF":5.1,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144021020","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"SSR42 is a novel regulator of cytolytic activity in <i>Staphylococcus aureus</i>.","authors":"Mary-Elizabeth Jobson, Brooke R Tomlinson, Emilee M Mustor, Emily A Felton, Andy Weiss, Clayton C Caswell, Lindsey N Shaw","doi":"10.1128/mbio.00772-25","DOIUrl":"https://doi.org/10.1128/mbio.00772-25","url":null,"abstract":"<p><p>SSR42 is the longest noncoding RNA in the <i>Staphylococcus aureus</i> cell and the second-most abundant transcript in the stationary-phase transcriptome, second only to RNAIII. It is highly conserved across strains and exhibits pronounced stability in stationary phase; however, the mechanism behind its regulatory role has yet to be fully elucidated. Herein, we used transcriptomic and proteomic approaches to probe the role of SSR42, revealing that it is a powerful, novel activator of the primary leukocidin LukAB. SSR42 is required for cytotoxicity toward, and escape from within, human neutrophils, and also mediates survival within human blood. We show that SSR42 wields this role via derepression by the peroxide repressor PerR in response to the presence of human neutrophils and governs <i>lukAB</i> induction in this niche. Importantly, this regulation is driven by direct RNA-RNA interaction, as we show binding of the 5' untranslated region (UTR) of the <i>lukAB</i> transcript with the 3' end of SSR42, which ultimately modulates transcript stability as well as translational activity. Finally, we demonstrate that this behavior is absolutely required for full virulence of <i>S. aureus</i> in murine models of both pneumonia and sepsis. Collectively, we present SSR42 as a pleiotropic regulatory RNA that acts as a nexus between environmental sensing and the regulation of pathogenesis, responding to environmental stimuli and host immune factors to bolster cytotoxic behavior and facilitate infection in <i>S. aureus</i>.IMPORTANCE<i>Staphylococcus aureus</i> is a master pathogen due to its formidable collection of virulence factors. These are tightly controlled by a diverse group of regulators that titrate their abundance to adapt to unique infectious niches. The role of regulatory RNAs in stress adaptation and pathogenesis is becoming increasingly more relevant in <i>S. aureus</i>. In this study, we provide the most comprehensive global analysis to date of just such a factor, SSR42. Specifically, we uncover that SSR42 is required for mediating cytotoxicity-one of the pillars of infection-in response to phagocytosis by human neutrophils. We find that SSR42 is induced by components of the host immune system and facilitates downstream activation of cytotoxic factors via RNA-RNA interactions. This illustrates that SSR42 forms a pivotal link between sensing the external environment and mediating resistance to oxidative stress while promoting virulence, solidifying it as a major global regulator in <i>S. aureus</i>.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0077225"},"PeriodicalIF":5.1,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143991157","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Erratum for Woo et al., \"<i>Acinetobacter baumannii</i> OmpA hinders host autophagy via the CaMKK2-reliant AMPK-pathway\".","authors":"Kyungho Woo, Dong Ho Kim, Ho-Sung Park, Man Hwan Oh, Je Chul Lee, Chul Hee Choi","doi":"10.1128/mbio.01224-25","DOIUrl":"https://doi.org/10.1128/mbio.01224-25","url":null,"abstract":"","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0122425"},"PeriodicalIF":5.1,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144008756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization of the family-level <i>Borreliaceae</i> pan-genome and development of an episomal typing protocol.","authors":"Kalya M Socarras, Mary C Marino, Joshua P Earl, Rachel L Ehrlich, Nicholas A Cramer, Joshua C Mell, Bhaswati Sen, Azad Ahmed, Richard T Marconi, Garth D Ehrlich","doi":"10.1128/mbio.00943-25","DOIUrl":"https://doi.org/10.1128/mbio.00943-25","url":null,"abstract":"<p><p>The <i>Borreliaceae</i> family includes many obligate parasitic bacterial species etiologically associated with a myriad of zoonotic borrelioses, including Lyme disease and vector-borne relapsing fevers. <i>Borreliaceae</i> infections are difficult to detect by both direct and indirect methods, often leading to delayed and missed diagnoses. Efforts to improve diagnostics center around the development of molecular diagnostics (MDx), but due to deep tissue sequestration and the lack of persistent bacteremias, even MDx assays suffer from a lack of sensitivity. Additionally, the extensive genomic heterogeneity among isolates, even within the same species, contributes to the lack of assay sensitivity, as single target assays, whether nucleic acid-based or serologically based, cannot provide universal coverage. This within-species heterogeneity is partly due to differences in replicon repertoires and genomic structures that have likely arisen to support the complex <i>Borreliaceae</i> life cycle necessary for these parasites to survive in multiple hosts, each with unique immune responses. We constructed a <i>Borreliaceae</i> family-level pan-genome and characterized the phylogenetic relationships among the constituent taxa, which supports the recent, although contested, taxonomy of splitting the family into at least two genera. Gene content profiles were created for the majority of the <i>Borreliaceae</i> replicons, providing for the first time their unambiguous molecular typing. Our characterization of the <i>Borreliaceae</i> pan-genome supports the splitting of the former <i>Borrelia</i> genus into two genera and provides for the phylogenetic placement of several non-species designated isolates. Mining this family-level pan-genome will enable the development of precision diagnostics corresponding to gene content-driven clinical outcomes while also providing targets for interventions.</p><p><strong>Importance: </strong>Using whole genome sequencing, we demonstrated that the bacteria that are transmitted by ticks and other arthropod vectors that cause Lyme disease and relapsing fevers, while related, do not belong within the same genus classification. In addition, through characterization of their highly atypical genomic structure, we were able to develop a genetic typing system that will help with future studies of how they cause disease while also providing targets for medical interventions.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0094325"},"PeriodicalIF":5.1,"publicationDate":"2025-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144034019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"c-di-GMP is required for swarming in <i>E. coli</i>, producing colanic acid that acts as surfactant.","authors":"YuneSahng Hwang, Marta Perez, Rebecca Holzel, Rasika M Harshey","doi":"10.1128/mbio.00916-25","DOIUrl":"https://doi.org/10.1128/mbio.00916-25","url":null,"abstract":"<p><p>Many bacteria use flagella to swim individually through bulk liquid or swarm collectively over a semi-solid surface. In <i>Escherichia coli</i>, c-di-GMP inhibits swimming via the effector protein YcgR. We show in this study that, contrary to its effect on swimming, a certain threshold level of c-di-GMP is required for swarming. Gene expression profiles first indicated that several c-di-GMP synthases<i>-dgcJ</i>, <i>dgcM</i>, and <i>dgcO</i>-were upregulated during swarming. Of these, we found DgcO to play a critical role in promoting the production of colanic acid-one of the three major exopolysaccharides in <i>E. coli</i>. DgcO has been reported to increase poly-β-1,6-N-acetylglucosamine (PGA) synthesis in <i>E. coli</i> as well. We show that colanic acid has hitherto-unknown surfactant properties that are expected to aid swarming.IMPORTANCEIt is well established that, in bacteria, c-di-GMP inhibits flagella-driven motility at various points in the pathway. Concomitantly, elevated c-di-GMP levels induce the expression and synthesis of a variety of exopolysaccharides that enmesh the bacteria in a biofilm, thereby also interfering with the flagella function. This study reports the surprising finding that, in <i>Escherichia coli</i>, the exopolysaccharide colanic acid is required to enable surface navigation and that the diguanylate cyclase DgcO is employed for this purpose. For surface navigation, there appears to be a sweet spot where c-di-GMP levels are just right to produce polysaccharides that can serve as surfactants and wetting agents rather than promote the formation of biofilms.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0091625"},"PeriodicalIF":5.1,"publicationDate":"2025-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144021058","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The AusAB non-ribosomal peptide synthetase of <i>Staphylococcus aureus</i> preferentially generates phevalin in host-mimicking media.","authors":"Adriana Moldovan, Markus Krischke, Claudia Huber, Clara Hans, Martin J Müller, Wolfgang Eisenreich, Thomas Rudel, Martin J Fraunholz","doi":"10.1128/mbio.00845-24","DOIUrl":"https://doi.org/10.1128/mbio.00845-24","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Non-ribosomal peptide synthetases (NRPSs) are modular multidomain enzymes responsible for the biosynthesis of various secondary metabolites in an mRNA template-independent manner. They are predominantly present in bacteria and fungi, where they synthesize a variety of products, including antibiotics, siderophores, toxins, and signaling molecules. The human pathogen &lt;i&gt;Staphylococcus aureus&lt;/i&gt; possesses one single NRPS, AusA, highly conserved in all sequenced &lt;i&gt;S. aureus&lt;/i&gt; strains. AusA incorporates the aromatic amino acids (AAAs) phenylalanine or tyrosine, as well as the branched-chain amino acids valine and leucine into three cyclic dipeptides collectively called aureusimines: phevalin, tyrvalin, and leuvalin. By using targeted metabolomics, we found that during growth in the common tissue culture medium RPMI1640, AusA preferentially synthesizes phevalin, despite similar availability for both phenylalanine and tyrosine. Upon cultivation in a chemically defined medium, however, the yields for both products are comparable, albeit with a slight preference for phevalin. Moreover, omission of either \"building block\" (phenylalanine, tyrosine, or valine) does not abrogate aureusimine biosynthesis, showing that &lt;i&gt;de novo&lt;/i&gt; biosynthesis of these amino acids is sufficient to yield aureusimine production. Cultivation of &lt;i&gt;S. aureus&lt;/i&gt; in a synthetic medium mimicking human nasal secretions, lacking tyrosine, results in marked phevalin production, despite moderate bacterial growth. Our report on culture medium composition-driven AAA incorporation by a bacterial NRPS provides a useful basis for linking bacterial cell metabolic status to the biosynthesis of secondary metabolites.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Importance: &lt;/strong&gt;Peptide and protein synthesis are fundamental processes in nature which are largely mediated by the ribosomal machinery. An alternative pathway for peptide synthesis is non-ribosomal mRNA template-independent synthesis, performed by so-called NRPSs. NRPSs are multi-enzyme complexes which serve the simultaneous role of template and biosynthetic machinery. They are mostly found in bacteria and fungi and are responsible for the biosynthesis of many pharmacologically significant products, including antibiotics, anticancer compounds, or immunosuppressants. The human pathogen &lt;i&gt;S. aureus&lt;/i&gt; possesses one such NRPS, AusA, which synthesizes three cyclic dipeptides termed \"aureusimines\" using the aromatic amino acids phenylalanine and tyrosine and the branched-chain amino acids leucine and valine. Although the biological role of aureusimines remains unknown, AusA appears to play a role in the interaction of &lt;i&gt;S. aureus&lt;/i&gt; with the host. In addition, owing to its minimal canonical NRPS structure and autonomous function (i.e., most NRPS pathways require the assembly of several NRPS proteins), AusA represents an excellent model system for studying such molecular assembly lines. Our observation is, to our knowledge, the first report of an NRPS ","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0084524"},"PeriodicalIF":5.1,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144021116","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Direct relationship between protein expression and progeny yield of herpes simplex virus 1.","authors":"Moeka Nobe, Yuhei Maruzuru, Kosuke Takeshima, Fumio Maeda, Hideo Kusano, Raiki Yoshimura, Takara Nishiyama, Hyeongki Park, Yoshitaka Kozaki, Shingo Iwami, Naoto Koyanagi, Akihisa Kato, Tohru Natsume, Shungo Adachi, Yasushi Kawaguchi","doi":"10.1128/mbio.00280-25","DOIUrl":"https://doi.org/10.1128/mbio.00280-25","url":null,"abstract":"<p><p>Although viral protein expression and progeny virus production were independently shown to be highly heterogeneous in individual cells, their direct relationship, analyzed by considering their heterogeneities, has not been investigated to date. To elucidate the direct relationship between viral protein expression and progeny virus production, we constructed a reporter herpes simplex virus 1 (HSV-1) by tagging Venus to the late protein Us11. We then separated the HSV-1-infected cell population into multiple subpopulations according to the fluorescence intensity of Venus-which reflected the expression of L proteins, largely constituting virion structural proteins-and titrated virus yields and performed electron microscopic analysis in each subpopulation. Our results revealed that infectious progeny virus production, as well as nucleocapsid maturation, was triggered only when L protein expression exceeded a specific threshold. This suggested the existence of a rate-limiting step in progeny virus production, with nucleocapsid maturation potentially being one such step.IMPORTANCEEarlier single-cell studies of virus-infected cells have revealed high heterogeneity in the state of viral gene expression and progeny virus yield. Notably, these two aspects have been shown independently, and therefore, the direct relationship between progeny virus production and viral gene expression has been unclear. This study, for the first time, demonstrated the direct and quantitative relationship between viral protein expression and progeny virus production by taking into account their heterogeneities and revealed a threshold for the levels of herpes simplex virus 1 protein expression for progeny virus production, thereby suggesting the existence of a rate-limiting step in progeny virus production.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0028025"},"PeriodicalIF":5.1,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143989475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The archaeal class <i>Nitrososphaeria</i> is a key component of the reproductive microbiome in sponges during gametogenesis.","authors":"Marta Turon, Vasiliki Koutsouveli, María Conejero, Sergi Taboada, Aida Verdes, José María Lorente-Sorolla, Cristina Díez-Vives, Ana Riesgo","doi":"10.1128/mbio.02019-24","DOIUrl":"https://doi.org/10.1128/mbio.02019-24","url":null,"abstract":"<p><p>Sponge-associated microbes play fundamental roles in regulating their hosts' physiology, yet their contribution to sexual reproduction has been largely overlooked. Most studies have concentrated on the proportion of the microbiome transmitted from parents to offspring, providing little evidence of the putative microbial role during gametogenesis in sponges. Here, we use 16S rRNA gene analysis to assess whether the microbial composition of five gonochoristic sponge species differs between reproductive and non-reproductive individuals and correlate these changes with their gametogenic stages. In sponges with mature oocytes, reproductive status did not influence either beta or alpha microbial diversity. However, in two of the studied species, <i>Geodia macandrewii</i> and <i>Petrosia ficiformis,</i> which presented oocytes at the previtellogenic stage, significant microbial composition changes were detected between reproductive and non-reproductive individuals. These disparities were primarily driven by differentially abundant taxa affiliated with the <i>Nitrososphaeria</i> archaeal class in both species. We speculate that the previtellogenic stages are more energetically demanding, leading to microbial changes due to the phagocytosis of microbes to meet nutritional demands during this period. Supporting our hypothesis, we observed significant transcriptomic differences in <i>G. macandrewii</i>, mainly associated with the immune system, indicating potential changes in the sponge's recognition system. Overall, we provide new insights into the possible roles of sponge microbiomes during reproductive periods, potentially uncovering critical interactions that support reproductive success.</p><p><strong>Importance: </strong>Our research explores the fascinating relationship between sponges and their resident microbes, focusing specifically on how these microbes might influence sponge reproduction. Sponges are marine animals known for their complex and beneficial partnerships with various microbes. While previous studies have mainly looked at how these microbes are passed from parent sponges to their offspring, our study is among the first to examine how microbial communities change during the different stages of sponge reproduction. By analyzing the microbial composition in five sponge species, we discovered that significant changes occur in species with premature oocytes, suggesting that microbes may play a crucial role in providing the necessary nutrients during early egg development. This work not only enhances our understanding of sponge biology but also opens up new avenues for studying how microbes support the reproductive success of their hosts in marine environments.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0201924"},"PeriodicalIF":5.1,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144008362","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stress-dependent activation of the <i>Listeria monocytogenes</i> virulence program ensures bacterial resilience during infection.","authors":"Mariya Lobanovska, Ying Feng, Jonathan Zhang, Allison H Williams, Daniel A Portnoy","doi":"10.1128/mbio.00719-25","DOIUrl":"https://doi.org/10.1128/mbio.00719-25","url":null,"abstract":"<p><p><i>Listeria monocytogenes (Lm</i>) is a Gram-positive, facultative intracellular pathogen that uses both a housekeeping (P1) and stress-activated (Sigma B-dependent) promoter (P2) to express the master virulence regulator PrfA. The Sigma B regulon contains over 300 genes known to respond to different stressors. However, the role of Sigma B in the regulation of <i>prfA</i> during the infection remains uncertain. To define pathways that lead to Sigma B-dependent <i>prfA</i> activation, we performed a genetic screen in L2 fibroblasts using ΔP1 <i>Lm</i> that only has the Sigma B-dependent promoter directly upstream of <i>prfA</i>. The screen identified transposon insertions in a large bacterial sensory organelle known as the stressosome. The absence of functional stressosome components resulted in heterogeneity within bacterial populations, with some bacteria behaving like wild type, while other members of the population exhibited defects in either vacuolar escape and/or cell-to-cell spread. We show that the heterogeneity of the stressosome mutants cannot be rescued by constitutive activation of PrfA. These data defined the importance of the stressosome in controlling bacterial homogeneity and characterized the function of the stressosome in robust virulence activation during infection. ΔP1 <i>Lm</i> model provides new opportunities to identify host-specific signals necessary for stressosome-dependent signaling during <i>Listeria</i> pathogenesis.IMPORTANCEMicrobial pathogens must adapt to varying levels of stress to survive. This study uncovered a link between stress sensing and activation of the virulence program in a facultative intracellular pathogen, <i>Listeria monocytogenes</i>. We show that host-imposed stress is sensed by the signaling machinery known as the stressosome to ensure robust and resilient virulence responses <i>in vivo</i>. Stressosome-dependent activation of the master virulence regulator PrfA was necessary to maintain <i>L. monocytogenes</i> homogeneity within the bacteria population during the transition between early and late stages of intracellular infection. This work also provides a model to further characterize how specific stress stimuli affect bacterial survival within the host<i>,</i> which is critical for our understanding of bacterial pathogenesis.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0071925"},"PeriodicalIF":5.1,"publicationDate":"2025-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144001208","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}