Molecular Microbiology最新文献

{"title":"The host Rab9a/Rab32 axis is actively recruited to the Trypanosoma cruzi parasitophorous vacuole and benefits the infection cycle.","authors":"Betiana Nebaí Salassa, Juan Agustín Cueto, María Cristina Vanrell, María Belén López, Albert Descoteaux, Carlos Alberto Labriola, Patricia Silvia Romano","doi":"10.1111/mmi.15217","DOIUrl":"10.1111/mmi.15217","url":null,"abstract":"<p><p>Trypanosoma cruzi, the etiological agent of Chagas disease is a protozoan parasite that infects phagocytic and non-phagocytic mammalian cells. At early stages of infection, trypomastigotes, the infective forms of this parasite, localize in a vesicular compartment called the T. cruzi parasitophorous vacuole until the exit of parasites to the host cell cytoplasm where continue their infective cycle. Rab proteins participate in the membrane traffic's molecular machinery, functioning as central regulators of vesicle recognition and transport. In previous work, we demonstrated that endocytic Rabs are key factors of the T. cruzi infection process in non-phagocytic cells, regulating the formation and the maturation of the vacuole. In this work, we identified and characterized other molecular components of the vesicular transport pathways and their participation in the T. cruzi infection. We found that Rab9a and Rab32, two regulators of the endocytic and autophagic pathways, were actively recruited to the T. cruzi vacuoles and favored the late stages of the infective process. The recruitment was specific and dependent on T. cruzi protein synthesis. Interestingly, Rab32 association depends on the presence of Rab9a in the vacuolar membrane, while the inhibition of the cysteine-protease cruzipain, a T. cruzi virulence factor, significantly decreases both Rab9a and Rab32 association with the vacuole. In summary, this work showed for the first time that specific molecules produced and secreted by the parasite can subvert intracellular components of host cells to benefit the infection. These new data shed light on the complex map of interactions between T. cruzi and the host cell and introduce concepts that can be useful in finding new forms of intervention against this parasite in the future.</p>","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":" ","pages":"643-659"},"PeriodicalIF":2.6,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139403717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Activation of innate immunity selectively compromises mitochondrial complex I, proline oxidation, and flight activity in the major arbovirus vector Aedes aegypti.","authors":"Alessandro Gaviraghi, Ana Beatriz F Barletta, Thiago Luiz Alves E Silva, Matheus P Oliveira, Marcos H F Sorgine, Marcus F Oliveira","doi":"10.1111/mmi.15269","DOIUrl":"10.1111/mmi.15269","url":null,"abstract":"<p><p>Aedes aegypti females are natural vectors of important arboviruses such as dengue, zika, and yellow fever. Mosquitoes activate innate immune response signaling pathways upon infection, as a resistance mechanism to fight pathogens and limit their propagation. Despite the beneficial effects of immune activation for insect vectors, phenotypic costs ultimately affect their fitness. However, the underlying mechanisms that mediate these fitness costs remain poorly understood. Given the high energy required to mount a proper immune response, we hypothesized that systemic activation of innate immunity would impair flight muscle mitochondrial function, compromising tissue energy demand and flight activity. Here, we investigated the dynamic effects of activation of innate immunity by intra-thoracic zymosan injection on A. aegypti flight muscle mitochondrial metabolism. Zymosan injection significantly increased defensin A expression in fat bodies in a time-dependent manner that compromised flight activity. Although oxidant levels in flight muscle were hardly altered, ATP-linked respiratory rates driven by mitochondrial pyruvate+proline oxidation were significantly reduced at 24 h upon zymosan injection. Oxidative phosphorylation coupling was preserved regardless of innate immune response activation along 24 h. Importantly, rotenone-sensitive respiration and complex I-III activity were specifically reduced 24 h upon zymosan injection. Also, loss of complex I activity compromised ATP-linked and maximal respiratory rates mediated by mitochondrial proline oxidation. Finally, the magnitude of innate immune response activation negatively correlated with respiratory rates, regardless of the metabolic states. Collectively, we demonstrate that activation of innate immunity is strongly associated with reduced flight muscle complex I activity with direct consequences to mitochondrial proline oxidation and flight activity. Remarkably, our results indicate a trade-off between dispersal and immunity exists in an insect vector, underscoring the potential consequences of disrupted flight muscle mitochondrial energy metabolism to arbovirus transmission.</p>","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":" ","pages":"683-703"},"PeriodicalIF":2.6,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140892081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Capsular Polysaccharide Production in Bacteria of the Mycoplasma Genus: A Huge Diversity of Pathways and Synthases for So-Called Minimal Bacteria.","authors":"Manon Vastel, Corinne Pau-Roblot, Séverine Ferré, Véronique Tocqueville, Chloé Ambroset, Corinne Marois-Créhan, Anne V Gautier-Bouchardon, Florence Tardy, Patrice Gaurivaud","doi":"10.1111/mmi.15325","DOIUrl":"https://doi.org/10.1111/mmi.15325","url":null,"abstract":"<p><p>Mycoplasmas are wall-less bacteria with many species spread across various animal hosts in which they can be pathogenic. Despite their reduced anabolic capacity, some mycoplasmas are known to secrete hetero- and homopolysaccharides, which play a role in host colonization through biofilm formation or immune evasion, for instance. This study explores how widespread the phenomenon of capsular homopolysaccharide secretion is within mycoplasmas, and investigates the diversity of both the molecules produced and the synthase-type glycosyltransferases responsible for their production. Fourteen strains representing 14 (sub)species from four types of hosts were tested in vitro for their polysaccharide secretion using both specific (immunodetection) and nonspecific (sugar dosage) assays. We evidenced a new, atypical homopolymer of β-(1 → 6)-glucofuranose (named glucofuranan) in the human pathogen Mycoplasma (M.) fermentans, as well as a β-(1 → 6)-glucopyranose polymer for the turkey pathogen M. iowae and galactan (β-(1 → 6)-galactofuranose) and β-(1 → 2)-glucopyranose for M. bovigenitalium infecting ruminants. Sequence and phylogenetic analyses revealed a huge diversity of synthases from varied Mycoplasma species. The clustering of these membrane-embedded glycosyltransferases into three main groups was only partially correlated to the structure of the produced homopolysaccharides.</p>","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142546490","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"(p)ppGpp Buffers Cell Division When Membrane Fluidity Decreases in Escherichia coli","authors":"Vani Singh, Rajendran Harinarayanan","doi":"10.1111/mmi.15323","DOIUrl":"https://doi.org/10.1111/mmi.15323","url":null,"abstract":"Fluidity is an inherent property of biological membranes and its maintenance (homeoviscous adaptation) is important for optimal functioning of membrane‐associated processes. The fluidity of bacterial cytoplasmic membrane increases with temperature or an increase in the proportion of unsaturated fatty acids and vice versa. We found that strains deficient in the synthesis of guanine nucleotide analogs (p)ppGpp and lacking FadR, a transcription factor involved in fatty acid metabolism exhibited a growth defect that was rescued by an increase in growth temperature or unsaturated fatty acid content. The strain lacking (p)ppGpp was sensitive to genetic or chemical perturbations that decrease the proportion of unsaturated fatty acids over saturated fatty acids. Microscopy showed that the growth defect was associated with cell filamentation and lysis and rescued by combined expression of cell division genes <jats:italic>ftsQ</jats:italic>, <jats:italic>ftsA</jats:italic>, and <jats:italic>ftsZ</jats:italic> from plasmid or the gain‐of‐function <jats:italic>ftsA</jats:italic>* allele but not over‐expression of <jats:italic>ftsN</jats:italic>. The results implicate (p)ppGpp in positive regulation of cell division during membrane fluidity loss through enhancement of FtsZ proto‐ring stability. To our knowledge, this is the first report of a (p)ppGpp‐mediated regulation needed for adaptation to membrane fluidity loss in bacteria.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"15 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2024-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142490773","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Enteric Bacterium Enterococcus faecalis Elongates and Incorporates Exogenous Short and Medium Chain Fatty Acids Into Membrane Lipids","authors":"Qi Zou, Huijuan Dong, John E. Cronan","doi":"10.1111/mmi.15322","DOIUrl":"https://doi.org/10.1111/mmi.15322","url":null,"abstract":"<i>Enterococcus faecalis</i> incorporates and elongates exogeneous short- and medium-chain fatty acids to chains sufficiently long to enter membrane phospholipid synthesis. The acids are activated by the <i>E. faecalis</i> fatty acid kinase (FakAB) system and converted to acyl-ACP species that can enter the fatty acid synthesis cycle to become elongated. Following elongation the acyl chains are incorporated into phospholipid by the PlsY and PlsC acyltranferases. This process has little effect on <i>de novo</i> fatty acid synthesis in the case of short-chain acids, but a greater effect with medium-chain acids. Incorporation of exogenous short-chain fatty acids in <i>E. faecalis</i> was greatly increased by overexpression of either AcpA, the acyl carrier protein of fatty acid synthesis, or the phosphate acyl transferase PlsX. The PlsX of <i>Lactococcus lactis</i> was markedly superior to the <i>E. faecalis</i> PlsX in incorporation of short-chain but not long-chain acids. These manipulations also allowed unsaturated fatty acids of lengths too short for direct transfer to the phospholipid synthesis pathway to be elongated and support growth of <i>E. faecalis</i> unsaturated fatty acid auxotrophic strains. Short- and medium-chain fatty acids can be abundant in the human gastrointestinal tract and their elongation by <i>E. faecalis</i> would conserve energy and carbon by relieving the requirement for total <i>de novo</i> synthesis of phospholipid acyl chains.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"27 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2024-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142385765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The dual role of a novel Sinorhizobium meliloti chemotaxis protein CheT in signal termination and adaptation.","authors":"Alfred Agbekudzi, Timofey D Arapov, Ann M Stock, Birgit E Scharf","doi":"10.1111/mmi.15303","DOIUrl":"10.1111/mmi.15303","url":null,"abstract":"<p><p>Sinorhizobium meliloti senses nutrients and compounds exuded from alfalfa host roots and coordinates an excitation, termination, and adaptation pathway during chemotaxis. We investigated the role of the novel S. meliloti chemotaxis protein CheT. While CheT and the Escherichia coli phosphatase CheZ share little sequence homology, CheT is predicted to possess an α-helix with a DXXXQ phosphatase motif. Phosphorylation assays demonstrated that CheT dephosphorylates the phosphate-sink response regulator, CheY1~P by enhancing its decay two-fold but does not affect the motor response regulator CheY2~P. Isothermal Titration Calorimetry (ITC) experiments revealed that CheT binds to a phosphomimic of CheY1~P with a K_D of 2.9 μM, which is 25-fold stronger than its binding to CheY1. Dissimilar chemotaxis phenotypes of the ΔcheT mutant and cheT DXXXQ phosphatase mutants led to the hypothesis that CheT exerts additional function(s). A screen for potential binding partners of CheT revealed that it forms a complex with the methyltransferase CheR. ITC experiments confirmed CheT/CheR binding with a K_D of 19 μM, and a SEC-MALS analysis determined a 1:1 and 2:1 CheT/CheR complex formation. Although they did not affect each other's enzymatic activity, CheT binding to CheY1~P and CheR may serve as a link between signal termination and sensory adaptation.</p>","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":" ","pages":"429-446"},"PeriodicalIF":2.6,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141856032","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cytosolic Factors Controlling PASTA Kinase-Dependent ReoM Phosphorylation.","authors":"Patricia Rothe, Sabrina Wamp, Lisa Rosemeyer, Jeanine Rismondo, Joerg Doellinger, Angelika Gründling, Sven Halbedel","doi":"10.1111/mmi.15307","DOIUrl":"10.1111/mmi.15307","url":null,"abstract":"<p><p>Bacteria adapt the biosynthesis of their envelopes to specific growth conditions and prevailing stress factors. Peptidoglycan (PG) is the major component of the cell wall in Gram-positive bacteria, where PASTA kinases play a central role in PG biosynthesis regulation. Despite their importance for growth, cell division and antibiotic resistance, the mechanisms of PASTA kinase activation are not fully understood. ReoM, a recently discovered cytosolic phosphoprotein, is one of the main substrates of the PASTA kinase PrkA in the Gram-positive human pathogen Listeria monocytogenes. Depending on its phosphorylation, ReoM controls proteolytic stability of MurA, the first enzyme in the PG biosynthesis pathway. The late cell division protein GpsB has been implicated in PASTA kinase signalling. Consistently, we show that L. monocytogenes prkA and gpsB mutants phenocopied each other. Analysis of in vivo ReoM phosphorylation confirmed GpsB as an activator of PrkA leading to the description of structural features in GpsB that are important for kinase activation. We further show that ReoM phosphorylation is growth phase-dependent and that this kinetic is reliant on the protein phosphatase PrpC. ReoM phosphorylation was inhibited in mutants with defects in MurA degradation, leading to the discovery that MurA overexpression prevented ReoM phosphorylation. Overexpressed MurA must be able to bind its substrates and interact with ReoM to exert this effect, but the extracellular PASTA domains of PrkA or MurJ flippases were not required. Our results indicate that intracellular signals control ReoM phosphorylation and extend current models describing the mechanisms of PASTA kinase activation.</p>","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":" ","pages":"514-533"},"PeriodicalIF":2.6,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142154613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Differential CheR Affinity for Chemoreceptor C-Terminal Pentapeptides Modulates Chemotactic Responses.","authors":"Félix Velando, Elizabet Monteagudo-Cascales, Miguel A Matilla, Tino Krell","doi":"10.1111/mmi.15305","DOIUrl":"10.1111/mmi.15305","url":null,"abstract":"<p><p>Many chemoreceptors contain a C-terminal pentapeptide at the end of a linker. In Escherichia coli, this pentapeptide forms a high-affinity binding site for CheR and phosphorylated CheB, and its removal interferes with chemoreceptor adaptation. Analysis of chemoreceptors revealed significant variation in their pentapeptide sequences, and bacteria often possess multiple chemoreceptors with differing pentapeptides. To assess whether this sequence variation alters CheR affinity and chemotaxis, we used Pectobacterium atrosepticum SCRI1043 as a model. SCRI1043 has 36 chemoreceptors, with 19 of them containing a C-terminal pentapeptide. We show that the affinity of CheR for the different pentapeptides varies up to 11-fold (K_D 90 nM to 1 μM). Pentapeptides with the highest and lowest affinities differ only in a single amino acid. Deletion of the cheR gene abolishes chemotaxis. The replacement of the pentapeptide in the PacC chemoreceptor with those of the highest and lowest affinities significantly reduced chemotaxis to its cognate chemoeffector, L-Asp. Altering the PacC pentapeptide also reduced chemotaxis to L-Ser, but not to nitrate, which are responses mediated by the nontethered PacB and PacN chemoreceptors, respectively. Changes in the pentapeptide sequence thus modulate the response of the cognate receptor and that of another chemoreceptor.</p>","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":" ","pages":"465-476"},"PeriodicalIF":2.6,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142046919","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tag Recycling in the Pup-Proteasome System is Essential for Mycobacterium smegmatis Survival Under Starvation Conditions.","authors":"Erez Zerbib, Roni Levin, Eyal Gur","doi":"10.1111/mmi.15312","DOIUrl":"10.1111/mmi.15312","url":null,"abstract":"<p><p>Many bacteria possess proteasomes and a tagging system that is functionally analogous to the ubiquitin system. In this system, Pup, the tagging protein, marks protein targets for proteasomal degradation. Despite the analogy to the ubiquitin system, where the ubiquitin tag is recycled, it remained unclear whether Pup is similarly recycled, given how the bacterial proteasome does not include a depupylase. We previously showed in vitro that as Pup lacks effective proteasome degradation sites, it is released from the proteasome following target degradation, remaining conjugated to a degradation fragment that can be later depupylated. Here, we tested this model in Mycobacterium smegmatis, using a Pup mutant that is effectively degraded by the proteasome. Our findings indicate that Pup recycling not only occurs in vivo but is also essential to maintain normal pupylome levels and to support bacterial survival under starvation conditions. Accordingly, Pup recycling is an essential process in the mycobacterial Pup-proteasome system.</p>","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":" ","pages":"504-513"},"PeriodicalIF":2.6,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142133259","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Atypical Mycobacterium abscessus BlaRI Ortholog Mediates Regulation of Energy Metabolism but Not β-Lactam Resistance.","authors":"Lauren E Bonefont, Haley C Davenport, Catherine T Chaton, Konstantin V Korotkov, Kyle H Rohde","doi":"10.1111/mmi.15314","DOIUrl":"10.1111/mmi.15314","url":null,"abstract":"<p><p>Mycobacterium abscessus (Mab) is highly drug resistant, and understanding regulation of antibiotic resistance is critical to future antibiotic development. Regulatory mechanisms controlling Mab's β-lactamase (Bla_Mab) that mediates β-lactam resistance remain unknown. S. aureus encodes a prototypical protease-mediated two-component system BlaRI regulating the β-lactamase BlaZ. BlaR binds extracellular β-lactams, activating an intracellular peptidase domain which cleaves BlaI to derepress blaZ. Mycobacterium tuberculosis (Mtb) encodes homologs of BlaRI (which we will denote as BlaIR to reflect the inverted gene order in mycobacteria) that regulate not only the Mtb β-lactamase, blaC, but also additional genes related to respiration. We identified orthologs of blaIR_Mtb in Mab and hypothesized that they regulate bla_Mab. Surprisingly, neither deletion of blaIR_Mab nor overexpression of only blaI_Mab altered bla_Mab expression or β-lactam susceptibility. However, BlaI_Mab did bind to conserved motifs upstream of several Mab genes involved in respiration, yielding a putative regulon that partially overlapped with BlaI_Mtb. Prompted by evidence that respiration inhibitors including clofazimine induce the BlaI regulon in Mtb, we found that clofazimine triggers induction of blaIR_Mab and its downstream regulon. Highlighting an important role for BlaIR_Mab in adapting to disruptions in energy metabolism, constitutive repression of the BlaI_Mab regulon rendered Mab highly susceptible to clofazimine. In addition to our unexpected findings that BlaIR_Mab does not regulate β-lactam resistance, this study highlights the novel role of mycobacterial BlaRI-type regulators in regulating electron transport and respiration.</p>","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":" ","pages":"583-597"},"PeriodicalIF":2.6,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142291742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}