mBio最新文献

{"title":"Gut microbiota dysbiosis and metabolic perturbations of bile/glyceric acids in major depressive disorder with IBS comorbidity.","authors":"Jia-Yu Du, Zhen-Jie Zhang, Li Tan, Jing-Yi Yang, Run-Nan Yang, Yi-Long Chen, Gui-Feng Tan, Jing Li, Wen-Jing Li, Lin Yang, Jia Cai, Dan-Lin Shen, Hong-Ru Zhu, Zhen-Xin Fan, Min-Lan Yuan, Wei Zhang","doi":"10.1128/mbio.02447-25","DOIUrl":"https://doi.org/10.1128/mbio.02447-25","url":null,"abstract":"<p><p>Major depressive disorder (MDD) and irritable bowel syndrome (IBS) exhibit high comorbidity, yet their shared pathophysiology remains unclear. Previous studies have primarily focused on the psychological health in the IBS population, without considering psychiatric diagnoses or stratifying different psychological states, potentially leading to biased findings. This study employed multi-omics approaches to characterize gut microbiota and serum metabolites in 120 MDD patients (47 with IBS and 73 without IBS) and 70 healthy controls (HCs). MDD with IBS patients showed significantly higher depression (Hamilton depression scale [HAMD-17]) and anxiety (Hamilton anxiety scale [HAMA-14]) scores than MDD-only patients (<i>P</i> < 0.05). Metagenomic sequencing of fecal samples revealed increased alpha diversity (Chao1/Shannon indices) and <i>Firmicutes</i> dominance in both MDD groups vs HC, while <i>Actinobacteria</i> enrichment specifically marked MDD with IBS. Functionally, MDD with IBS uniquely activated D-amino acid/glycerolipid metabolism pathways (Kyoto Encyclopedia of Genes and Genomes). Serum metabolomics identified comorbid-specific perturbations: downregulation of bile acids (CDCA, GCDCA, GCDCA-3S) and upregulation of glyceric acid/glutaconic acid. Our study also found that <i>Eggerthella lenta</i> and <i>Clostridium scindens</i> are differentially abundant bacteria that are involved in bile acid metabolism, and that microbial genes (e.g., K03738) are associated with glyceric acid production. These findings implicate gut microbiota-driven bile acid/glyceric acid dysregulation in MDD with IBS comorbidity, supporting the gut-brain axis as a therapeutic target for probiotics or microbiota transplantation.IMPORTANCEMajor depressive disorder (MDD) exhibits a high comorbidity rate with irritable bowel syndrome (IBS). Our study, conducted on 120 MDD patients (47 of whom were comorbid with IBS) and a control group of 70 individuals, revealed that MDD-IBS comorbid patients demonstrated significantly higher depression/anxiety scores. Multi-omics analysis indicated substantial alterations in the gut microbiota (e.g., <i>Firmicutes</i>, <i>Actinobacteria</i>) and serum metabolites (e.g., bile acids, glyceric acid) among MDD-IBS patients, which were associated with specific metabolic pathways. Therefore, the new aspect of this study was the inclusion of patients with MDD but without IBS symptoms, which provided a deeper understanding of the intestinal microbiota dysregulation associated with comorbid IBS and MDD. These findings suggest that there may be involvement of the gut-brain axis, providing new research directions for potential therapeutic targets.CLINICAL TRIALSThis study is registered with the Chinese Clinial Trial Registry as ChiCTR2100041598.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0244725"},"PeriodicalIF":4.7,"publicationDate":"2025-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145239102","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":"Expanding cholera serosurveillance to vaccinated populations.","authors":"Forrest K Jones, Taufiqur R Bhuiyan, Damien M Slater, Ralph Ternier, Kian Robert Hutt Vater, Ashraful I Khan, Fahima Chowdhury, Kennia Visieres, Rajib Biswas, Mohammad Kamruzzaman, Edward T Ryan, Stephen B Calderwood, Regina C LaRocque, Richelle C Charles, Daniel T Leung, Justin Lessler, Louise C Ivers, Firdausi Qadri, Jason B Harris, Andrew S Azman","doi":"10.1128/mbio.01898-25","DOIUrl":"https://doi.org/10.1128/mbio.01898-25","url":null,"abstract":"<p><p>Mass oral cholera vaccination campaigns targeted at subnational areas with high incidence are central to global cholera elimination efforts. Serological surveillance offers a complementary approach to address gaps in clinical surveillance in these regions. However, similar immune responses from vaccination and infection can lead to overestimates of the incidence of infection. To address this, we analyzed antibody dynamics in infected and vaccinated individuals to refine seroincidence estimation strategies for partially vaccinated populations. We tested 757 longitudinal serum samples from confirmed <i>Vibrio cholerae</i> O1 cases and uninfected contacts in Bangladesh as well as vaccinees from Bangladesh and Haiti, using a multiplex bead assay to measure IgG, IgM, and IgA binding to five cholera-specific antigens. Infection elicited stronger and broader antibody responses than vaccination, with rises in cholera toxin B-subunit (CTB) and toxin-coregulated pilus A (TcpA) antibodies uniquely associated with infection. Previously proposed random forest models frequently misclassified vaccinated individuals as recently infected (over 20% at some time points) during the first 4 months post-vaccination. To address this, we developed new random forest models incorporating vaccinee data, which kept false-positive rates among vaccinated (1%) and unvaccinated (6%) individuals low without a significant loss in sensitivity. Simulated serosurveys demonstrated that unbiased seroincidence estimates could be achieved within 21 days of vaccination campaigns by ascertaining the vaccination status of participants or applying updated models. These approaches to overcome biases in serological surveillance enable reliable seroincidence estimation even in areas with recent vaccination campaigns enhancing the utility of serological surveillance as an epidemiologic tool in moderate-to-high cholera incidence settings.</p><p><strong>Importance: </strong>Serological surveillance can improve how we monitor cholera in high-burden areas where clinical surveillance is limited. However, vaccination can produce immune responses similar to infection, leading to overestimates in seroincidence. This study extends seroincidence estimation techniques using machine learning models to partially vaccinated populations. We analyzed antibody dynamics from vaccinated and infected individuals to develop methods that reduce the misclassification of vaccinated individuals as recently infected. These methods enable reliable seroincidence estimates in areas with recent vaccination campaigns, providing a step toward better epidemiologic monitoring in the context of global cholera control initiatives. Studies in other populations are needed to further validate our results and understand their generalizability.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0189825"},"PeriodicalIF":4.7,"publicationDate":"2025-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145239066","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":"Separation of <i>Pseudomonas aeruginosa</i> type IV pilus-dependent twitching motility and surface-sensing responses.","authors":"Rebecca Barnshaw, Hanjeong Harvey, Matthew McCallum, Tomas Lazarou, Sheryl Nguyen, Ikram Qaderi, Veronica Tran, Nathan Roberge, Christopher Geiger, George A O'Toole, P Lynne Howell, Lori L Burrows","doi":"10.1128/mbio.02521-25","DOIUrl":"https://doi.org/10.1128/mbio.02521-25","url":null,"abstract":"<p><p>Many functions of <i>Pseudomonas aeruginosa</i> type IVa pili, including twitching motility and surface sensing, depend on dynamic cycles of filament assembly and disassembly powered by the cytoplasmic ATPases PilB, PilT, and PilU. Deletion of <i>pilT</i> results in loss of twitching and pilus-specific bacteriophage susceptibility, while non-twitching <i>pilU</i> mutants remain susceptible to pilus-specific phages, indicating that they still produce retractable pili. <i>pilU</i> mutants have high basal levels of the secondary messenger cyclic AMP (cAMP) that normally increases following surface contact, suggesting aberrant surface sensing. To better understand PilU's role in pilus biology, we solved its X-ray crystal structure and used phylogenetic analyses to identify conserved differences between PilT and PilU. Chemical mutagenesis followed by whole-genome sequencing was used to identify suppressors in the Δ<i>pilU</i> mutant background that restored twitching motility. The mutations mapped to the major pilin, PilA, or the pilus tip adhesin, PilY1. Both the position and nature of the substitutions in PilA impacted restoration of motility, and it was dependent on functional PilT. Complementation of most <i>pilU</i> suppressors with PilU <i>in trans</i> further increased motility, while the expression of wild-type PilA <i>in trans</i> decreased motility in a dose-dependent manner. Notably, cAMP levels remained elevated in most twitching <i>pilU</i> suppressor mutants, showing that surface sensing and motility can be uncoupled. Together, our data suggest that the bacterial response to surfaces reflects a complex interaction of PilU function with specific alleles of PilY1 and PilA that together modulate pilus dynamics and function.</p><p><strong>Importance: </strong>The ability of bacteria to sense and respond to contact with surfaces is important for triggering changes in secondary messenger levels and gene expression, leading to the formation of biofilms and increased production of virulence factors. For <i>Pseudomonas aeruginosa</i>, the expression of functional type IVa pili is important for the accumulation of cyclic AMP (cAMP) following surface contact. Deletion of the PilT retraction ATPase paralog PilU leads to loss of pilus-mediated twitching motility but also high intracellular levels of cAMP, a phenotype mimicking that of surface-adapted cells. Here, we isolated twitching suppressors of a <i>pilU</i> deletion mutant that mapped to the pilin subunit PilA or pilus-tip adhesin PilY1 and showed that for most, elevated cAMP levels did not decrease when motility was restored. Twitching was dependent on functional PilT, and complementation with PilU further increased twitching for most mutants. These data show that in permissive contexts, PilU is not required for twitching motility, providing new insights into mechanisms of bacterial surface sensing and evolution of type IVa pilus motor function.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0252125"},"PeriodicalIF":4.7,"publicationDate":"2025-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145238814","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":"Coordinated regulation of Mdr1- and Cdr1-mediated protection from antifungals by the Mrr1 transcription factor in emerging <i>Candida</i> spp.","authors":"Dhanabala-Subhiksha Rajesh-Khanna, Carolina G Piña Páez, Susu He, Elora G Dolan, Kiran S Mirpuri, Jason E Stajich, Deborah A Hogan","doi":"10.1128/mbio.01323-25","DOIUrl":"https://doi.org/10.1128/mbio.01323-25","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Infections caused by the emerging pathogenic yeast &lt;i&gt;Clavispora (Candida) lusitaniae&lt;/i&gt; can be difficult to manage due to multi-drug resistance. Resistance to the frontline antifungal fluconazole (FLZ) in &lt;i&gt;Candida&lt;/i&gt; spp. is commonly acquired through gain-of-function (GOF) mutations in the gene encoding the transcription factor Mrr1. These activated Mrr1 variants enhance FLZ efflux via upregulation of the multi-drug transporter gene &lt;i&gt;MDR1&lt;/i&gt;. Recently, it was reported that, unlike in the well-studied &lt;i&gt;Candida albicans&lt;/i&gt; species, &lt;i&gt;C. lusitaniae&lt;/i&gt; and &lt;i&gt;Candida parapsilosis&lt;/i&gt; with activated Mrr1 also have high expression of &lt;i&gt;CDR1&lt;/i&gt;, which encodes another multi-drug transporter with overlapping but distinct transported substrate profiles and Cdr1-dependent FLZ resistance. To better understand the mechanisms of Mrr1 regulation of &lt;i&gt;MDR1&lt;/i&gt; and &lt;i&gt;CDR1&lt;/i&gt;, and other co-regulated genes, we performed Cleavage Under Targets and Release Using Nuclease (CUT&RUN) analysis of Mrr1 binding sites. Mrr1 bound the promoter regions of &lt;i&gt;MDR1&lt;/i&gt; and &lt;i&gt;CDR1&lt;/i&gt;, as well as &lt;i&gt;FLU1&lt;/i&gt;, which encodes another transporter capable of FLZ efflux. Mdr1 and Cdr1 independently contributed to the decreased susceptibility of the &lt;i&gt;MRR1&lt;sup&gt;GOF&lt;/sup&gt;&lt;/i&gt; strains against diverse clinical azoles and other antifungals, including 5-flucytosine. A consensus motif, CGGAGWTAR, enriched in Mrr1-bound &lt;i&gt;C. lusitaniae&lt;/i&gt; DNA was also conserved upstream of &lt;i&gt;MDR1&lt;/i&gt; and &lt;i&gt;CDR1&lt;/i&gt; across species, including &lt;i&gt;C. albicans&lt;/i&gt;. CUT&RUN and RNA-seq data were used to define the Mrr1 regulon, which includes genes involved in transport, stress response, and metabolism. Activated and inducible Mrr1 bound similar regions in the promoters of Mrr1 regulon genes. Our studies provide new evolutionary insights into the coordinated regulation of multi-drug transporters and potential mechanism(s) that aid secondary resistance acquisition in emerging &lt;i&gt;Candida&lt;/i&gt;.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Importance: &lt;/strong&gt;Understanding antifungal resistance in emerging &lt;i&gt;Candida&lt;/i&gt; pathogens is essential to managing treatment failures and guiding the development of new therapeutic strategies. Like other &lt;i&gt;Candida&lt;/i&gt; species, the environmental opportunistic fungal pathogen &lt;i&gt;Clavispora&lt;/i&gt; (&lt;i&gt;Candida&lt;/i&gt;) &lt;i&gt;lusitaniae&lt;/i&gt; can acquire resistance to the antifungal fluconazole by overexpression of the multi-drug efflux pump Mdr1 through gain-of-function (GOF) mutations in the gene encoding the transcription factor Mrr1. Here, we show that &lt;i&gt;C. lusitaniae&lt;/i&gt; Mrr1 also directly regulates &lt;i&gt;CDR1&lt;/i&gt;, another major multi-drug transporter gene, along with &lt;i&gt;MDR1&lt;/i&gt;. In strains with activated Mrr1, upregulation of &lt;i&gt;MDR1&lt;/i&gt; and &lt;i&gt;CDR1&lt;/i&gt; protects against diverse antifungals, potentially aiding the rise of other resistance mutations. Mrr1 also regulates several stress response and metabolism genes, thereby providing new perspectives into the physiology of drug-resistant strains.","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0132325"},"PeriodicalIF":4.7,"publicationDate":"2025-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145239040","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":"Screening of gene function in cell intoxication by CNF1 links Sec61 translocon to Rac1 GTPase activity.","authors":"Eléa Paillares, Nathalie Deboosere, Stéphane Descorps-Declere, Maud Marechal, Daniel Gillet, Caroline Demangel, Amel Mettouchi, Priscille Brodin, Emmanuel Lemichez","doi":"10.1128/mbio.02585-24","DOIUrl":"https://doi.org/10.1128/mbio.02585-24","url":null,"abstract":"<p><p>The CNF1 toxin from extraintestinal pathogenic <i>Escherichia coli</i> (ExPEC) deamidates glutamine 61 of Rac1 small GTPase, as well as its equivalents in RhoA and Cdc42 into glutamic acid. This post-translational modification of Rho proteins abrogates the hydrolysis of GTP into GDP, thereby enhancing signal transduction. Meanwhile, the sustained GTP-loading of Rac1 Q61E sensitizes it to ubiquitin-mediated proteasomal degradation catalyzed by the HACE1 E3 ligase rate-limiting factor, leading to a cellular depletion of Rac1 over time. We report data from a quantitative genome-wide screen of siRNAs inhibiting CNF1-mediated cellular depletion of Rac1 in primary human cells. As best hits, we identified a group of three siRNAs targeting the Sec61A1 subunit of the Sec61 translocon, as well as HACE1 and the Lu/BCAM host cell receptor of CNF1. We extend these findings by identifying a group of siRNAs targeting genes involved in ER and Golgi homeostasis and trafficking. Functional studies showed that both chemical and genetic inhibition of Sec61A1 dampens GTP-loading and membrane association of Rac1 in CNF1-intoxicated cells, while the proper deamidation of RhoA provides a control of CNF1 cytosolic action. Finally, we extend these findings by showing that inhibition of <i>N</i>-glycosylation of neo-synthesized proteins in the ER abrogates Rac1 GTP-loading in CNF1-treated cells. Collectively, these data point to a control of Rac1 signaling operated by protein biosynthesis and <i>N</i>-glycosylation in the ER.IMPORTANCEThe remarkable evolutionary convergence of bacterial effectors from pathogens toward the host small GTPase Rac1, the master regulator of the actin cytoskeleton, confers to these microbes an enhanced capacity to invade host cells and tissues. The CNF1 toxin, a colonization factor of the gastrointestinal tract produced by pathogenic strains of <i>Escherichia coli,</i> has been instrumental in deciphering the regulation and function of Rac1. By performing a whole-genome screen based on CNF1 action, we establish the key requirement of Sec61 translocon-dependent protein biosynthesis and <i>N</i>-glycosylation at the endoplasmic reticulum for proper activation of Rac1 in intoxicated cells. Our data connect the Sec61 translocon and <i>N</i>-glycosylation of neo-synthesized proteins at the endoplasmic reticulum in the control of the activity of Rac1 and other Rho GTPases.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0258524"},"PeriodicalIF":4.7,"publicationDate":"2025-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145232945","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":"<i>Chlamydia trachomatis</i> subverts neutrophil cell death pathways through RIP3 and Mcl-1 manipulation.","authors":"Rebecca Koch, Naveen Challagundla, Kathrin Stelzner, Thomas Rudel","doi":"10.1128/mbio.02098-25","DOIUrl":"https://doi.org/10.1128/mbio.02098-25","url":null,"abstract":"<p><p><i>Chlamydia trachomatis</i>, an obligate intracellular pathogen, manipulates host cells to evade immune detection, contributing to sexually transmitted diseases with severe complications. Neutrophils, short-lived effector cells, form the first line of innate immune defense against infection. Here, we demonstrate that <i>Chlamydia</i> infection extends the lifespan of human neutrophils, creating a cellular niche for its own survival. Lifespan extension involves the neutrophil PI3K/Akt- and the NF-κB signaling pathways. In addition, infection activates the necroptotic effector receptor-interacting protein kinase 3 (RIP3) without inducing cell death. Instead, RIP3 stabilizes the anti-apoptotic protein Mcl-1, enhancing neutrophil survival. This extended survival of neutrophils correlates with an increased number of infectious <i>Chlamydia</i> particles. Mcl-1 plays a critical role in neutrophil survival, lifespan extension, and <i>Chlamydia</i> survival. Notably, inhibiting RIP3 reduces Mcl-1 levels in neutrophils without affecting their survival. Under these conditions, however, <i>Chlamydia</i> load increases, and the dependence on Mcl-1 is bypassed. Our data reveal a new role for necroptosis in neutrophil defense against intracellular <i>Chlamydia</i>, highlighting a complex interplay between RIP3 and Mcl-1 that extends neutrophil lifespan and enhances <i>Chlamydia</i> survival within these hostile cells.IMPORTANCEThis study reveals how <i>Chlamydia trachomatis</i>, a common sexually transmitted bacterium, manipulates the body's first immune responders, the neutrophils, to aid its own survival. Normally short-lived, neutrophils live longer when infected by <i>Chlamydia</i>, creating a safe environment for the bacteria. This lifespan extension is driven by specific cell survival signals and a protein called RIP3, which surprisingly does not cause cell death here, but helps stabilize another protein, Mcl-1, that keeps neutrophils alive. Blocking RIP3 reduces Mcl-1, but <i>Chlamydia</i> still manages to survive, suggesting it can adapt to changes in the host environment. These findings uncover a new layer of complexity in how our immune system interacts with infections and could inform future strategies for treating <i>Chlamydia</i> and similar infections.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0209825"},"PeriodicalIF":4.7,"publicationDate":"2025-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145232947","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":"Self-resistance mechanism to acyldepsipeptide antibiotics in the <i>Streptomyces</i> producer.","authors":"Dhana Thomy, Laura Reinhardt, Elisa Liebhart, Mirita Franz-Wachtel, Boris Maček, Peter Sass, Heike Brötz-Oesterhelt","doi":"10.1128/mbio.01652-25","DOIUrl":"https://doi.org/10.1128/mbio.01652-25","url":null,"abstract":"<p><p>Clp proteases are ubiquitous in bacteria and play an important role in regulatory proteolysis and in maintaining protein homeostasis within the bacterial cell. They consist of a tetradecameric, proteolytic ClpP core and associated AAA+ Clp-ATPases. The Clp system of <i>Streptomyces</i> is unusually complex, comprising up to five ClpP homologs (ClpP1-ClpP5) and three Clp-ATPases (ClpX, ClpC1, and ClpC2). Streptomycetes produce a plethora of secondary metabolites, including potent acyldepsipeptide (ADEP) antibiotics, which target ClpP. We have previously reported on the operation mode of the <i>Streptomyces</i> ClpP1P2 protease and identified a novel <i>clpP</i> gene (named <i>clpP_ADEP</i>) as a resistance determinant encoded near the ADEP biosynthesis gene cluster. However, the molecular function of ClpP_ADEP remains enigmatic. Here, we report on the molecular self-resistance mechanism to ADEP via ClpP_ADEP and its interaction with the Clp system in the ADEP producer <i>Streptomyces hawaiiensis</i> NRRL 15010. By combining cell-based and <i>in vitro</i> studies, we show that ClpP_ADEP interferes with the formation of the ClpP1P2 complex and inhibits the proteolytic activity of ClpP1. Moreover, ClpP_ADEP forms a functional complex with ClpP2 and Clp-ATPases. By these means, ClpP_ADEP protects the producer cell against ADEP in a two-pronged approach. On the one hand, it prevents ADEP from corrupting ClpP1 to degrade delicate essential proteins and polypeptides. On the other hand, ClpP_ADEP ensures the survival of the producer cells by maintaining the housekeeping function of the Clp protease in regulatory proteolysis.IMPORTANCEAcyldepsipeptide (ADEP) antibiotics kill bacteria using an unusual mechanism of action, that is, the multilayered deregulation and activation of ClpP, the proteolytic core of the bacterial Clp protease. ADEP is highly effective in killing Gram-positive bacteria, including methicillin-resistant <i>Staphylococcus aureus</i> (MRSA) and vancomycin-resistant enterococci (VRE). Considering the elaborate mechanism of action of ADEP as well as the complexity of the essential Clp system in <i>Streptomyces</i> with up to five ClpP homologs as potential ADEP targets, the question arises: how does the producer ensure self-resistance in such a complex system? Here, we describe the molecular mechanism of self-resistance to ADEP in the producer <i>Streptomyces hawaiiensis</i> NRRL 15010, which is based on the presence of a phylogenetically distinct ClpP protein in the genome of the ADEP producer strain.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0165225"},"PeriodicalIF":4.7,"publicationDate":"2025-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145232973","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":"Honey wasps differ from other wasps in possessing large gut communities dominated by host-restricted bacteria.","authors":"Jo-Anne C Holley, Alexia N Martin, Anna T Pham, Jennifer Schlauch, Nancy A Moran","doi":"10.1128/mbio.02608-24","DOIUrl":"https://doi.org/10.1128/mbio.02608-24","url":null,"abstract":"<p><p>Honey-feeding social bees, including honey bees, bumble bees, and stingless bees, possess distinctive gut bacterial communities that provide benefits to hosts, such as defense against pathogens and parasites. Members of these communities are transmitted through social interactions within colonies. The Mexican honey wasp (<i>Brachygastra mellifica</i>) represents an independent origin of honey-storing within a group of social Hymenoptera. Honey wasps feed on and store honey, but, unlike bees, they prey on other insects as a protein source and do not consume pollen. We surveyed the gut bacterial communities of Mexican honey wasps across sites within Texas using 16S ribosomal RNA profiling, and we estimated bacterial titer per bee using quantitative PCR. For comparison, we also surveyed non-honey-feeding wasps from six families, collected in the same region. We found that honey wasp communities are dominated by characteristic bacterial species. In contrast, other wasps had lower absolute titers and more variable communities, dominated by environmental bacteria. Honey wasps from all sampled nests contained strains of <i>Bifidobacterium</i> and <i>Bombilactobacillus</i> that were closely related to symbionts of bumble bees and other bees, suggesting acquisition via host-switching. Some individuals also harbored a close relative of <i>Candidatus</i> Schmidhempelia bombi (Orbaceae), an uncultured bumble bee symbiont, again suggesting host-switching. The most prevalent species was an uncultured <i>Lactobacillus</i> that potentially represents an independent acquisition of environmental <i>Lactobacillus</i>. The transition to honey feeding, combined with a highly social life history, appears to have facilitated the establishment of a bacterial community with similarities to those of social bees.IMPORTANCEHoney-feeding social insects such as honey bees and bumble bees have conserved gut bacterial communities that are transmitted among nestmates. These bacteria benefit hosts by providing defense against pathogens and potentially by contributing to pollen digestion. The bacterial communities of wasps are less studied. Whereas most wasps are carnivorous and consume nectar, honey wasps (<i>Brachygastra</i> spp.) store and eat honey. Here, we address the consequences of this dietary shift for the gut community. Using field collections of Mexican honey wasps and other co-occurring wasps, we found that honey wasps have distinctive gut bacterial communities. These include several bacteria most closely related to bacteria in bumble bees, suggesting their acquisition via host-switching. Solitary wasps and social wasps that do not make honey have smaller gut communities dominated by environmental bacteria, suggesting that honey feeding has shaped the gut bacterial communities of honey wasps.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0260824"},"PeriodicalIF":4.7,"publicationDate":"2025-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145213230","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 iron-regulated small regulatory RNA IsrR modulates expression of genes utilized for dioxygen metabolism and heme synthesis in <i>Staphylococcus aureus</i>.","authors":"Gustavo Rios-Delgado, Riley McFarlane, Vincent Zheng, Jisun Kim, Dane Parker, Thomas Kehl-Fie, David Lalaouna, Jeffrey M Boyd","doi":"10.1128/mbio.01415-25","DOIUrl":"https://doi.org/10.1128/mbio.01415-25","url":null,"abstract":"<p><p>Bacterial regulatory RNAs (sRNAs) are commonly short non-coding RNAs that function as pleiotropic regulators by post-transcriptionally impacting mRNA stability and/or translation. They play significant roles in bacterial physiology and are typically expressed in response to specific environmental stimuli such as nutrient limitation. The bacterial pathogen <i>Staphylococcus aureus</i> faces decreased access to essential metal ions, including iron, in the mammalian host via a process called nutritional immunity. In response to host-mediated iron limitation, <i>S. aureus</i> expresses the sRNA IsrR, which coordinates an iron-sparing response by downregulating the expression of mRNAs coding for iron-requiring proteins or processes. Herein, we utilized MS2-Affinity Purification coupled with RNA Sequencing (MAPS) to reveal the <i>in vivo</i> IsrR interaction network. Analysis of co-purified RNAs revealed previously unpredicted putative IsrR targets coding for proteins associated with iron-requiring processes. We validated that IsrR directly interacts with nine targets <i>in vitro</i>. We demonstrate physiological roles for IsrR in mediating heme biosynthesis, aerobic respiration, and the detoxification of oxygen radicals. These activities are critical for pathogenesis, and this study establishes how <i>S. aureus</i> leverages these processes to adapt to iron scarcity, which is commonly encountered in the mammalian host.</p><p><strong>Importance: </strong><i>Staphylococcus aureus</i> causes numerous and varied infections in mammals, making it a significant public health burden and concern. The prevalence of <i>S. aureus</i> infections is due to its robust repertoire of virulence factors and its ability to adapt to host microenvironments. Elucidation of the metabolic processes and pathways that promote adaptation to host-promoted stressors provides information about host-pathogen interactions. It could also aid the development of new antimicrobials or unveil treatment and prevention strategies. One common stress bacteria encounter within the mammalian hosts is limited access to iron. In response to iron scarcity, <i>S. aureus</i> expresses the regulatory sRNA IsrR. Here, we identified mRNAs that associate with IsrR. We verified that IsrR targets mRNAs that code for proteins involved in aerobic respiration, the metabolism of reactive oxygen species, and heme synthesis. This work provides significant insight into how <i>S. aureus</i> responds to host-mediated iron starvation.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0141525"},"PeriodicalIF":4.7,"publicationDate":"2025-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145212462","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":"WDR81 represses IKK-mediated expression of pro-survival genes to regulate apoptosis.","authors":"Sannoong Hu, Pranav Danthi","doi":"10.1128/mbio.02722-25","DOIUrl":"https://doi.org/10.1128/mbio.02722-25","url":null,"abstract":"<p><p>Apoptosis is a common host response to virus infection. The extent and timing of apoptosis following infection is controlled by the balance between the strength of signals that activate death-inducing and survival-promoting pathways in cells. In many cell types, infection with mammalian orthoreovirus (reovirus) results in induction of cell death by apoptosis late in infection. In this study, we uncovered that WD repeat-containing protein 81 (WDR81) is required for apoptosis induction after reovirus infection. The requirement for WDR81 for apoptosis induction is not unique to reovirus because cells lacking WDR81 are also resistant to apoptosis induced by other agonists. We find that in cells deficient in WDR81, expression of several pro-survival genes is upregulated. The expression of these genes is controlled by the inhibitor of κB kinase (IKK) complex-nuclear factor of kB (NFκB) signaling pathway. When IKK signaling is blocked in WDR81-deficient cells, pro-survival gene expression is restored to normal levels, and the cells regain their susceptibility to cell death triggers. Our work uncovers a new function for WDR81 in controlling apoptosis. Additionally, it reveals a previously unknown link between an endosomally localized protein, WDR81, and IKK-NFκB signaling.IMPORTANCEVirus infection often results in the death of the infected cells. Cell death prior to generation of virus progeny limits the spread of infection to neighboring cells and therefore can be beneficial to the host. However, cell death might also cause tissue destruction and could contribute to viral disease. It is therefore important to understand how cell death is controlled. Here, we uncover a cell death-regulating role for WD repeat-containing protein 81 (WDR81)-a cellular protein that has not been previously implicated in affecting cell death. We find that when this protein is absent, cells express a much greater level of survival signals. These survival signals prevent efficient induction of cell death. By investigating how these survival signals are expressed, we reveal a new link between WDR81 and nuclear factor of kB (NFκB), a well-known cellular survival pathway.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0272225"},"PeriodicalIF":4.7,"publicationDate":"2025-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145212382","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}