mBio最新文献

{"title":"Gene regulatory network resource aids in predicting trans-acting regulators of biosynthetic gene clusters in <i>Aspergillus fumigatus</i>.","authors":"Hye-Won Seo, Jin Woo Bok, Nancy P Keller","doi":"10.1128/mbio.03874-24","DOIUrl":"10.1128/mbio.03874-24","url":null,"abstract":"<p><p>The field of secondary metabolism has greatly benefitted from computational advances in recent years. This has been particularly true for fungal natural product studies. Strides in genome mining have led to the identification of an extraordinary number of secondary metabolite biosynthetic gene clusters (BGCs) across the fungal Kingdom and metabologenomic platforms can group BGCs into gene cluster families and link them to initial chemical structures. Missing are computational applications focused on identifying BGC regulatory networks. Here, we applied the new online gene regulatory network resource, GRAsp (<u>G</u>ene <u>R</u>egulation of <i><u>Asp</u>ergillus fumigatus</i>), to identify unknown and unpredictable BGC trans-acting transcriptional/metabolite production modules. GRAsp correctly predicted a two-component regulatory module composed of the transcription factors (TFs), RogA (<u>r</u>egulation <u>o</u>f <u>g</u>liotoxin) and HsfA, which negatively regulate the gliotoxin BGC and are also involved in gliotoxin self-protection. RogA functions through the repression of <i>gliZ,</i> the pathway-specific gliotoxin TF, and HsfA functions by activating <i>rogA</i> expression. Furthermore, GRAsp identified TFs that regulate the production of two BGCs lacking pathway-specific TFs, the helvolic acid and fumitremorgin BGCs, respectively. Finally, the known TF, NsdD, was predicted and found to regulate the hexadehydroastechrome BGC. These advances highlight the power of inference algorithms to uncover unpredictable networks in specialized metabolite synthesis.IMPORTANCEToxic secondary metabolites are virulence factors of the opportunistic fungal pathogen <i>Aspergillus fumigatus,</i> yet the transcriptional networks regulating secondary metabolite production remain elusive. Uncovering novel regulators without any prior information is challenging. Computational programs have gained prominence in the field of secondary metabolite research due to their accuracy and ability to handle vast amounts of data, including DNA, RNA, and protein data. In this study, a newly developed online computer platform, Gene Regulation of <i>A. fumigatus</i>, was used to identify five regulators involved in the production of several <i>A. fumigatus</i> toxins, including gliotoxin, helvolic acid, fumitremorgin, and hexadehydroastechrome. This work illustrates the potential for discovering new trans-acting regulators and mechanisms of secondary metabolite regulation through the examination of computational gene regulatory networks.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0387424"},"PeriodicalIF":5.1,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11898546/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143441219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Large diversity in the O-chain biosynthetic cluster within populations of Pelagibacterales.","authors":"Jose M Haro-Moreno, Mario López-Pérez, Carmen Molina-Pardines, Francisco Rodriguez-Valera","doi":"10.1128/mbio.03455-24","DOIUrl":"10.1128/mbio.03455-24","url":null,"abstract":"<p><p>Genomic diversity in prokaryotic species is largely due to the existence of extensive pangenomes, allowing different gene complements to be drawn depending on the strain. Here, we have studied the diversity of the O-chain polysaccharide biosynthesis cluster (OBC) in marine bacteria of the Pelagibacterales order as a proxy to measure such genetic diversity in a single population. The study of single-amplified genomes (SAGs) from the whole order found a pattern similar to that of other well-studied microbes, such as the Enterobacteriales or <i>Alteromonas</i>, where distinct OBCs represent strains containing different gene pools. We found that most of the OBC sharing happened among individuals of the same clonal frame (>99% average nucleotide identity). Moreover, given the parsimonious way this cluster changes, the diversity of the OBCs can be extrapolated to the size of the population's pangenome. This assumes that different OBCs correspond to lineages containing unique flexible gene pools, as seen in the aforementioned microbes. Through long-read metagenomics, we could detect 380 different OBCs at a single Mediterranean sampling site. Within a single population (single species and sample) of the endemic Ia.3/VII (gMED) genomospecies, we identified 158 OBCs, of which 130 were unique. These findings suggest that the gene pool within a single population might be substantial (several thousands). While this figure is large, it aligns with the complexity of the dissolved organic matter that these organisms can potentially degrade.IMPORTANCEDifferent strains of the same bacterial species contain very different gene pools. This has been long known by epidemiologists. However, it is unknown what gene pool is present in a single set of environmental conditions, i.e., the same time and place in free-living bacteria. Here, we have leveraged information from SAGs to analyze the diversity of the gene cluster coding for the O-chain polysaccharide, a typical component of the flexible gene pool classically used as a tool to differentiate strains in clinical microbiology. It evolves at a similar rate to the rest of the genome and does not seem to be affected by an arms race with phages. One single species of Pelagibacteriales (gMED) revealed an astounding diversity in one sample studied by long-read metagenomics. Our results point to a large gene pool (local pangenome) present in a single population, which is critical to interpreting the biological meaning of the pangenome, <i>i.e</i>., it provides intrapopulation diversity rather than characterizing strains with different distribution in time and/or space.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0345524"},"PeriodicalIF":5.1,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11898729/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143449235","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"SENP1-SIRT3 axis mediates glycolytic reprogramming to suppress inflammation during <i>Listeria monocytogenes</i> infection.","authors":"Yan Xiong, Yongliang Du, Feng Lin, Beibei Fu, Dong Guo, Zhou Sha, Rong Tian, Rui Yao, Lulu Wang, Zixuan Cong, Bohao Li, Xiaoyuan Lin, Haibo Wu","doi":"10.1128/mbio.02524-24","DOIUrl":"https://doi.org/10.1128/mbio.02524-24","url":null,"abstract":"<p><p><i>Listeria monocytogenes,</i> a foodborne pathogen, has the ability to invade intestinal mucosal cells, undergo intracellular proliferation, activate host immune responses, and induce diseases such as colitis. We have demonstrated that sentrin-specific protease 1 (SENP1) functions as a protective gene in the host, suppressing the inflammatory response triggered by <i>Listeria monocytogenes</i>. The host's SENP1-SIRT3 axis plays a critical role in regulating inflammation during <i>Listeria monocytogenes</i> infection. Our findings reveal that overexpression of SENP1, particularly under <i>Listeria monocytogenes</i> infection conditions (MOI = 20), effectively suppresses inflammation through modulation of glycolysis. Mechanistically, during <i>Listeria monocytogenes</i> infection, SENP1 accumulates in the mitochondria, facilitating the de-SUMOylation and activation of sirtuin 3 (SIRT3). Activated SIRT3 then regulates the deacetylation of pyruvate kinase M2 (PKM2), leading to a decrease in glycolytic intermediates, downregulation of glycolysis-related gene expression, and suppression of inflammation. Taken together, our study provides a deeper understanding of the mechanistic role of the SENP1-SIRT3 axis in the regulation of inflammation, offering novel insights, and strategies for the treatment and prevention of inflammatory diseases.</p><p><strong>Importance: </strong>Sentrin-specific protease 1 (SENP1)-sirtuin 3 (SIRT3) has never been reported in the regulation of bacteria-induced inflammation. Our study demonstrated that SENP1 acted as a protective factor against <i>Listeria</i>-induced inflammation by promoting SIRT3 activation and subsequent metabolic reprogramming. The SENP1-SIRT3 axis served not only as an essential signaling pathway for regulating mitochondrial metabolic responses to metabolic stress but also responds to bacterial invasion and plays a protective role in the organism. Our findings provide a basis for further research into targeting the SENP1-SIRT3 signaling pathway for the treatment of bacterial infections.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0252424"},"PeriodicalIF":5.1,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143605461","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":"Introducing mGems, <i>mBio</i>'s new review type.","authors":"Marcio L Rodrigues, Jacob S Yount, Vinayaka R Prasad, Arturo Casadevall","doi":"10.1128/mbio.02622-24","DOIUrl":"10.1128/mbio.02622-24","url":null,"abstract":"","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0262224"},"PeriodicalIF":5.1,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11898556/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142978639","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Identification of intestinal mediators of <i>Caenorhabditis elegans</i> DBL-1/BMP immune signaling shaping gut microbiome composition.","authors":"Dan Kim, Kenneth Trang, Barbara Pees, Siavash Karimzadegan, Rahul Bodkhe, Sabrina Hammond, Michael Shapira","doi":"10.1128/mbio.03703-24","DOIUrl":"10.1128/mbio.03703-24","url":null,"abstract":"<p><p>The composition of the gut microbiome is determined by a complex interplay of diet, host genetics, microbe-microbe interactions, abiotic factors, and stochasticity. Previous studies have demonstrated the importance of host genetics in community assembly of the <i>Caenorhabditis elegans</i> gut microbiome and identified a central role for DBL-1/BMP immune signaling in determining the abundance of gut <i>Enterobacteriaceae</i>. However, the effects of DBL-1 signaling on gut bacteria were found to depend on its activation in extra-intestinal tissues, highlighting a gap in our understanding of the proximal factors that determine microbiome composition. In the present study, we used RNA-seq gene expression analysis of wildtype, <i>dbl-1</i> and <i>sma-3</i> mutants, and <i>dbl-1</i> over-expressors to identify candidate DBL-1/BMP targets that may mediate the pathway's effects on gut commensals. Bacterial colonization experiments in mutants, or following RNAi-mediated knock-down of candidate genes specifically in the intestine, demonstrated their local contribution to intestinal control of <i>Enterobacteriaceae</i> abundance. Furthermore, epistasis analysis suggested that these contributions were downstream of the DBL-1 pathway, together suggesting that examined candidates were intestinal effectors and mediators of DBL-1 signaling, contributing to the shaping of gut microbiome composition.IMPORTANCECompared to the roles of diet, environmental availability, or lifestyle in determining gut microbiome composition, that of genetic factors is the least understood and often underestimated. The identification of intestinal effectors of distinct molecular functions that control enteric bacteria offers a glimpse into the genetic logic of microbiome control as well as a list of targets for future exploration of this logic.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0370324"},"PeriodicalIF":5.1,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11898619/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143059627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Carbon upshift in <i>Lactococcus cremoris</i> elicits immediate initiation of proteome-wide adaptation, coinciding with growth acceleration and pyruvate dissipation switching.","authors":"Berdien van Olst, Sjef Boeren, Jacques Vervoort, Michiel Kleerebezem","doi":"10.1128/mbio.02990-24","DOIUrl":"10.1128/mbio.02990-24","url":null,"abstract":"<p><p>Fitness optimization in a dynamic environment requires bacteria to adapt their proteome in a tightly regulated manner by altering protein production and/or degradation. Here, we investigate proteome adaptation in <i>Lactococcus cremoris</i> following a sudden nutrient upshift (e.g., nutrients that allow faster growth) and focus especially on the fate of redundant proteins after the shift. Protein turnover analysis demonstrated that <i>L. cremoris</i> cultures shifted from galactose to glucose, immediately accelerate growth and initiate proteome-wide adjustment toward glucose-optimized composition. Redundant proteins were predominantly adjusted by lowering (or stopping) protein production combined with dilution by growth. However, pyruvate formate lyase activator (PflA) was actively degraded, which appears correlated to reduced 4Fe-4S cofactor availability. Active PflA removal induces the shutdown of galactose-associated mixed acid fermentation to accelerate the switch toward glucose-associated homolactic fermentation. Our work deciphers molecular adjustments upon environmental change that drive physiological adaptation, including growth rate and central energy metabolism.IMPORTANCEBacteria adapt to their environment by adjusting their molecular makeup, in particular their proteome, which ensures fitness optimization under the newly encountered environmental condition. We present a detailed analysis of proteome adaptation kinetics in <i>Lactococcus cremoris</i> following its acute transition from galactose to glucose media, as an example of a sudden nutrient quality upshift. Analysis of the replacement times of individual proteins after the nutrient upshift established that the entire proteome is instantly adjusting to the new condition, which coincides with immediate growth rate acceleration and metabolic adaptation. The latter is driven by the active removal of the pyruvate formate lyase activator protein that is pivotal in controlling pyruvate dissipation in <i>L. cremoris</i>. Our work exemplifies the amazing rate of molecular adaptation in bacteria that underlies physiological adjustments, including growth rate and carbon metabolism. This mechanistic study contributes to our understanding of adaptation in <i>L. cremoris</i> during the dynamic conditions it encounters during (industrial) fermentation, even though environmental transitions in these processes are mostly more gradual than the acute shift studied here.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0299024"},"PeriodicalIF":5.1,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11898756/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143458584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Myxosortase: an intramembrane protease that sorts MYXO-CTERM proteins to the cell surface.","authors":"Tingting Guo, Daniel H Haft, Daniel Wall","doi":"10.1128/mbio.04067-24","DOIUrl":"https://doi.org/10.1128/mbio.04067-24","url":null,"abstract":"<p><p>Cell surface proteins determine how cells interact with their biotic and abiotic environments. In social myxobacteria, a C-terminal protein sorting tag called MYXO-CTERM is universally found within the Myxococcota phylum, where their genomes typically contain dozens of proteins with this motif. MYXO-CTERM harbors a tripartite architecture: a short signature motif containing an invariant cysteine, followed by a transmembrane helix and a short arginine-rich C-terminal region localized in the cytoplasm. In <i>Myxococcus xanthus</i>, MYXO-CTERM is predicted to be posttranslationally lipidated and cleaved for subsequent cell surface localization by the type II secretion system. Here, following our bioinformatic discovery, we experimentally show that myxosortase (MrtX, MXAN_2755) is responsible for the C-terminal cleavage and cell surface anchoring of TraA, a prototypic cell surface receptor. The cleavage by MrtX depends on conserved cysteines within the MYXO-CTERM motif of TraA. <i>M. xanthus</i> mutants lacking myxosortase are defective in TraA-mediated outer membrane exchange and exhibit cell envelope defects. In a heterologous <i>Escherichia coli</i> expression system, the MYXO-CTERM motif is cleaved when MrtX is co-expressed. Therefore, MrtX represents a new family of sorting enzyme that enables cell surface localization of MYXO-CTERM proteins.IMPORTANCEThe CPBP (CaaX protease and bacteriocin processing) protease family is widespread across the three domains of life. Despite considerable research on eukaryotic homologs, prokaryotic CPBP family members remain largely unexplored. In this study, we experimentally reveal the function of a novel CPBP protease called myxosortase. Our findings show that myxosortase is responsible for the C-terminal cleavage and cell surface anchoring of substrate proteins containing MYXO-CTERM motifs in <i>Myxococcus xanthus</i>. MYXO-CTERM cleavage also occurred in a heterologous <i>Escherichia coli</i> host when myxosortase is co-expressed. This is the first report that a CPBP protease is involved in protein sorting in prokaryotes. This work provides important insights into the biogenesis and anchoring of cell surface proteins in gram-negative bacteria.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0406724"},"PeriodicalIF":5.1,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143605459","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":"E3 ubiquitin ligase MARCH5 positively regulates Japanese encephalitis virus infection by catalyzing the K27-linked polyubiquitination of viral E protein and inhibiting MAVS-mediated type I interferon production.","authors":"Chenxi Li, Chenyang Tang, Xiqian Liu, Ying Liu, Linjie Zhang, Jing Shi, Qingyu Li, Mingan Sun, Yanhua Li","doi":"10.1128/mbio.00208-25","DOIUrl":"https://doi.org/10.1128/mbio.00208-25","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Membrane-associated RING-CH-type finger (MARCH) proteins, a class of E3 ubiquitin ligases, have been reported to be involved in the infection of multiple viruses and the regulation of type I interferon (IFN) production. However, the specific role and mechanisms by which MARCH proteins influence Japanese encephalitis virus (JEV) infection remain poorly understood. Here, we systematically investigate the functional relevance of MARCH proteins in JEV replication by examining the effects of siRNA-mediated knockdown of MARCHs on viral infection. We identified MARCH5 as a positive regulator of JEV replication. The knockout of MARCH5 dramatically reduced viral yields, whereas its overexpression significantly enhanced JEV replication. Mechanistically, MARCH5 specifically interacts with the JEV envelope (E) protein and promotes its K27-linked polyubiquitination at the lysine (K) residues 136 and 166. This ubiquitination enhances viral attachment to permissive cells. Substituting these lysine residues with arginine (R) attenuated JEV replication &lt;i&gt;in vitro&lt;/i&gt; and reduced viral virulence &lt;i&gt;in vivo&lt;/i&gt;. Furthermore, JEV infection upregulated the expression of MARCH5. We also discovered that MARCH5 degrades mitochondrial antiviral-signaling protein (MAVS) through the ubiquitin-proteasome pathway by catalyzing its K48-linked ubiquitination, thereby inhibiting type I IFN production in JEV-infected cells. This suppression of type I IFN further facilitates JEV infection. In conclusion, these findings disclosed a novel role of MARCH5 in positively regulating JEV infection and revealed an important mechanism employed by MARCH5 to regulate the innate immune response.IMPORTANCEJEV is the leading cause of viral encephalitis in many countries of Asia with an estimated 100,000 clinical human cases and causes economic loss to the swine industry. Until now, there is no clinically approved antiviral for the treatment of JEV infection. Although vaccination prophylaxis is widely regarded as the most effective strategy for preventing Japanese encephalitis (JE), the incidence of JE cases continues to rise. Thus, a deeper understanding of virus-host interaction will enrich our knowledge of the mechanisms underlying JEV infection and identify novel targets for the development of next-generation live-attenuated vaccines and antiviral therapies. To the best of our knowledge, this study is the first to identify MARCH5 as a pro-viral host factor that facilitates JEV infection. We elucidated two distinct mechanisms by which MARCH5 promotes JEV infection. First, MARCH5 interacts with viral E protein and mediates the K27-linked ubiquitination of E protein at the K136 and K166 residues to facilitate efficient viral attachment. Furthermore, double mutations of K136R-K166R attenuated JEV infection &lt;i&gt;in vitro&lt;/i&gt; and reduced viral virulence in mice. Second, the upregulated expression of MARCH5 induced by JEV infection further suppresses the RIG-I-like receptor (RLR) signaling pat","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0020825"},"PeriodicalIF":5.1,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143605450","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":"Dehydration-induced <i>Ae-Aper50</i> regulates midgut infection in <i>Aedes aegypti</i> mosquitoes.","authors":"Anastasia Accoti, Margaret Becker, Angel Elma I Abu, Julia Vulcan, Ruimei Jun, Steven G Widen, Massamba Sylla, Vsevolod L Popov, Laura B Dickson","doi":"10.1128/mbio.01207-24","DOIUrl":"10.1128/mbio.01207-24","url":null,"abstract":"<p><p>Climate change is predicted to increase the spread of mosquito-borne viruses, but genetic mechanisms underlying the influence of environmental variation on the ability of insect vectors to transmit human pathogens is unknown. In response to a changing climate, mosquitoes will experience longer periods of drought. An important physiological response to dry environments is the protection against dehydration, here defined as desiccation tolerance. While temperature is known to impact interactions between mosquito and virus, the role of dehydration remains unknown. We identified two genetically diverse lines of the mosquito <i>Aedes aegypti</i>, a major arbovirus vector, with marked differences in desiccation tolerance. To determine the genetic response to dehydration between these contrasting lines, we compared gene expression profiles between desiccant- and non-desiccant-treated individuals in both the desiccation-tolerant and -susceptible lines by RNAseq. Gene expression analysis demonstrated that several genes are differentially expressed in response to desiccation stress between desiccation-tolerant and -susceptible lines. The most highly expressed transcript under desiccation stress in the desiccation-susceptible line encodes a peritrophin protein, <i>Ae-Aper50</i>. Peritrophins play a crucial role in peritrophic matrix formation in the mosquito midgut after a bloodmeal. Gene silencing of <i>Ae-Aper50</i> by RNAi demonstrated that expression of <i>Ae-Aper50</i> is required for survival of the desiccation-susceptible line under desiccation stress, but not for the desiccation-tolerant line. Moreover, the knockdown of <i>Ae-Aper50</i> resulted in higher Zika virus (ZIKV) infection rates in the desiccation-tolerant line and increased ZIKV viral replication in the desiccation susceptible line, and higher chikungunya virus (CHIKV) infection rates in the desiccation-tolerant line. Altogether, these results provide a link between protection against desiccation and midgut infection, which has important implications in predicting how climate change will impact mosquito-borne viruses.</p><p><strong>Importance: </strong>Climate change will have profound impacts on the burden of viruses transmitted by mosquitoes. While we know how changes in temperature impact mosquito physiology and dynamics of viral replication within the mosquito, there is a complete lack of knowledge in how low humidity, or drought tolerance, will impact interactions between mosquitoes and arboviruses. Understanding how drought tolerance will alter mosquito infection with arboviruses is critical in predicting and preventing the impact that climate change will have on mosquito-borne viruses. This work demonstrates a functional link between dehydration tolerance and midgut infection. This knowledge significantly enhances our understanding of how the predicted increase in droughts could impact the dynamics of mosquito-borne viruses.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0120724"},"PeriodicalIF":5.1,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11898677/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143023851","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Frequently arising ESX-1-associated phase variants influence <i>Mycobacterium tuberculosis</i> fitness in the presence of host and antibiotic pressures.","authors":"Michael J Luna, Peter O Oluoch, Jiazheng Miao, Peter Culviner, Kadamba Papavinasasundaram, Eleni Jaecklein, Scarlet S Shell, Thomas R Ioerger, Sarah M Fortune, Maha R Farhat, Christopher M Sassetti","doi":"10.1128/mbio.03762-24","DOIUrl":"10.1128/mbio.03762-24","url":null,"abstract":"<p><p><i>Mycobacterium tuberculosis</i> (Mtb) exhibits an impressive ability to adapt to rapidly changing environments, despite its genome's apparent stability. Recently, phase variation through indel formation in homopolymeric tracts (HT) has emerged as a potentially important mechanism promoting adaptation in Mtb. This study examines the impact of common phase variants associated with the ESX-1 type VII secretion system, focusing on a highly variable HT upstream of the ESX-1 regulatory factor, <i>espR</i>. By engineering this frequently observed indel into an isogenic background, we demonstrate that a single nucleotide insertion in the <i>espR</i> 5'UTR causes post-transcriptional upregulation of EspR protein abundance and corresponding alterations in the EspR regulon. Consequently, this mutation increases the expression of ESX-1 components in the <i>espACD</i> operon and enhances ESX-1 substrate secretion. We find that this indel specifically increases isoniazid resistance without impacting the effectiveness of other drugs tested. Furthermore, we show that two distinct observed HT indels that regulate either <i>espR</i> translation or <i>espACD</i> transcription increase bacterial fitness in a mouse infection model. The presence of multiple ESX-1-associated HTs provides a mechanism to combinatorially tune protein secretion, drug sensitivity, and host-pathogen interactions. More broadly, these findings support emerging data that Mtb utilizes HT-mediated phase variation to direct genetic variation to certain sites across the genome in order to adapt to changing pressures.</p><p><strong>Importance: </strong><i>Mycobacterium tuberculosis</i> (Mtb) is responsible for more deaths worldwide than any other single infectious agent. Understanding how this pathogen adapts to the varied environmental pressures imposed by host immunity and antibiotics has important implications for the design of more effective therapies. In this work, we show that the genome of Mtb contains multiple contingency loci that control the activity of the ESX-1 secretion system, which is critical for interactions with the host. These loci consist of homopolymeric DNA tracts in gene regulatory regions that are subject to high-frequency reversible variation and act to tune the activity of ESX-1. We find that variation at these sites increases the fitness of Mtb in the presence of antibiotic and/or during infection. These findings indicate that Mtb has the ability to diversify its genome in specific sites to create subpopulations of cells that are preadapted to new conditions.</p>","PeriodicalId":18315,"journal":{"name":"mBio","volume":" ","pages":"e0376224"},"PeriodicalIF":5.1,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11898584/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143052976","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}