Summary While studying virulence gene regulation in Vibrio cholerae during infection of the host small intestine, we identified VieA as a two‐component response regulator that contributes to activating expression cholera toxin. Here report represses transcription exopolysaccharide synthesis ( vps ) genes involved biofilm formation by mechanism independent its phosphorelay and DNA‐binding activities. controls intracellular concentration cyclic nucleotide second messenger diguanylate...

The newly recognized bacterial second messenger 3′,5′-cyclic diguanylic acid (cyclic diguanylate (c-di-GMP)) has been shown to regulate a wide variety of behaviors and traits. Biosynthesis degradation c-di-GMP have attributed the GGDEF EAL protein domains, respectively, based primarily on genetic evidence. Whereas domain was demonstrated possess cyclase activity in vitro, not tested directly for phosphodiesterase activity. This study describes analysis hydrolysis by an purified system....

The cyclic dinucleotide second messenger diguanylate (c-diGMP) has been implicated in regulation of cell surface properties several bacterial species, including Vibrio cholerae. Expression genes required for V. cholerae biofilm formation is activated by an increased intracellular c-diGMP concentration. response regulator VieA, which contains a domain responsible degradation c-diGMP, to maintain low concentration and repress formation. VieSAB three-component signal transduction system was,...

Cyclic diguanylate (c-di-GMP) is an allosteric activator and second messenger implicated in the regulation of a variety biological processes diverse bacteria. In Vibrio cholerae, c-di-GMP has been shown to inversely regulate biofilm-specific virulence gene expression, suggesting that signaling important for transition V. cholerae from environment host. However, mechanism behind this remains unknown. Recently, it was proposed PilZ protein domain represents c-di-GMP-binding domain. Here we...

Vibrio cholerae, the causative agent of cholera, is a facultative human pathogen with intestinal and aquatic life cycles. The capacity V. cholerae to recognize respond fluctuating parameters in its environment critical survival. In many microorganisms, second messenger, 3',5'-cyclic diguanylic acid (c-di-GMP), believed be important for integrating environmental stimuli that affect cell physiology. Sequence analysis genome has revealed an abundance genes encoding proteins either GGDEF...

A key to the pathogenic success of Mycobacterium tuberculosis (Mtb), causative agent tuberculosis, is capacity survive within host macrophages. Although several factors required for this survival have been identified, a comprehensive knowledge such and how they work together manipulate environment benefit bacterial are not well understood. To systematically identify Mtb intracellular growth, we screened an arrayed, non-redundant transposon mutant library by high-content imaging characterize...

Mycobacterium tuberculosis causes 10 million cases of active TB disease and over 1 deaths worldwide each year. treatment is complex, requiring at least 6 months therapy with a combination antibiotics.

Onset of the adaptive immune response in mice infected with Mycobacterium tuberculosis is accompanied by slowing bacterial replication and establishment a chronic infection. Stabilization numbers during phase infection dependent on activity gamma interferon (IFN-γ)-inducible nitric oxide synthase (NOS2). Previously, we described differential signature-tagged mutagenesis screen designed to identify M. "counterimmune" mechanisms reported isolation three mutants H37Rv strain background...

Mycobacterium tuberculosis persists in the tissues of mammalian hosts despite inducing a robust immune response dominated by macrophage-activating cytokine gamma interferon (IFN-γ). We identified M. phosphate-specific transport (Pst) system component PstA1 as factor required to resist IFN-γ-dependent immunity. A ΔpstA1 mutant was fully virulent IFN-γ(-/-) mice but attenuated wild-type (WT) and lacking specific IFN-γ-inducible mechanisms: nitric oxide synthase (NOS2), phagosome-associated p47...

The Mycobacterium tuberculosis phosphate-specific transport (Pst) system controls gene expression in response to phosphate availability by inhibiting the activation of SenX3-RegX3 two-component under phosphate-rich conditions, but mechanism communication between these systems is unknown. In Escherichia coli, inhibition PhoR-PhoB conditions requires both Pst and PhoU, a putative adaptor protein. E. coli PhoU also involved formation persisters, subpopulation phenotypically antibiotic-tolerant...

Mycobacterium tuberculosis releases membrane vesicles (MV) that modulate host immune responses and aid in iron acquisition, although they may have additional unappreciated functions. MV production appears to be a regulated process, but virR remains the only characterized genetic regulator of vesiculogenesis. Here, we present data supporting role for M. Pst/SenX3-RegX3 signal transduction system regulating production. Deletion pstA1, which encodes transmembrane component phosphate-specific...

Mycobacterium tuberculosis uses the Type VII ESX secretion systems to transport proteins across its complex cell wall. ESX-5 has been implicated in M. virulence, but regulatory mechanisms controlling were unknown. Here we uncover a link between and Pst/SenX3-RegX3 system that controls gene expression response phosphate availability. The DNA-binding regulator RegX3 is normally activated by limitation. Deletion of pstA1, which encodes Pst uptake component, causes constitutive activation RegX3....

Abstract The tuberculosis necrotizing toxin (TNT) is the major cytotoxicity factor of Mycobacterium (Mtb) in macrophages. TNT C-terminal domain outer membrane protein CpnT and gains access to cytosol kill macrophages infected with Mtb. However, molecular mechanisms secretion trafficking are largely unknown. A comprehensive analysis five type VII systems Mtb revealed that ESX-4 system required for export surface accessibility TNT. Furthermore, ESX-2 permeabilization phagosomal addition ESX-1...

Introduction Tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) remains a major global health threat. The only available vaccine Bacille Calmette-Guérin (BCG) does not prevent adult pulmonary TB. New effective TB vaccines should aim to stimulate robust T cell responses in the lung mucosa achieve high protective efficacy. We have previously developed novel viral vector based on recombinant Pichinde virus (PICV), non-pathogenic arenavirus with low seroprevalence humans, and...

ABSTRACT Differences in whole-genome expression patterns between the classical and El Tor biotypes of Vibrio cholerae O1 were determined under conditions that induce virulence gene biotype. A total 524 genes (13.5% genome) found to be differentially expressed two biotypes. The encoding proteins required for biofilm formation, chemotaxis, transport amino acids, peptides, iron was higher These differences may contribute enhanced survival capacity biotype environmental reservoirs. factors than...

The EspA protein of Mycobacterium tuberculosis is essential for the type VII ESX-1 secretion apparatus, which delivers principal virulence factors ESAT-6 and CFP-10. In this study, site-directed mutagenesis was performed to elucidate its influence on system. Replacing Trp(55) (W55) or Gly(57) (G57) residues in putative W-X-G motif with arginines impaired CFP-10 vitro attenuated M. tuberculosis. Phe(50) (F50) Lys(62) (K62) residues, flank motif, arginine alanine, respectively, destabilized...

New drugs are needed to shorten and simplify treatment of tuberculosis caused by Mycobacterium . Metabolic pathways that M requires for growth or survival during infection represent potential targets anti-tubercular drug development. Genes metabolic essential in standard laboratory culture conditions have been defined genome-wide genetic screens. However, whether these genes has not comprehensively explored because mutant strains cannot be generated using methods. Here we show the...

Phosphorelay systems are important mediators of signal transduction during bacterial adaptation to new environments. Previously we described the vieSAB operon, encoding a putative three-protein component phosphorelay involved in regulating Vibrio cholerae virulence gene expression. At least part regulatory activity VieSAB is exerted through cyclic diguanylate (c-di-GMP)-degrading response regulator VieA. So far no direct evidence that encodes system exists. In addition, role VieS plays...

ABSTRACT Mycobacterium tuberculosis requires the phosphate-sensing signal transduction system Pst/SenX3-RegX3 to resist host immune responses. A Δ pstA1 mutant lacking a Pst phosphate uptake component is hypersensitive diverse stress conditions in vitro and attenuated vivo due constitutive expression of starvation-responsive RegX3 regulon. Transcriptional profiling revealed aberrant certain pe ppe genes. PE PPE proteins, defined by conserved N-terminal domains containing Pro-Glu (PE) or...

The genes encoding cholera toxin (CT), ctxAB, are coregulated with those for other Vibrio cholerae virulence factors by a cascade of transcriptional activators, including ToxR, TcpP, and ToxT. Additional regulators that modulate expression ctxAB during infection were recently identified in genetic selection. A transposon insertion vieS, the sensor kinase VieSAB three-component signal transduction system, resulted failure to induce ctxA-recombinase fusion murine infection. To determine which...

Vibrio cholerae is a facultative intestinal pathogen that lives in aquatic environments, often association with planktonic species. In the suckling mouse, oral inoculation V. leads to colonization and symptoms of diarrheal disease. Results reported here indicate role for alternative sigma factor, RpoS, this model cholera. We constructed within rpoS multiple independent mutations which consistently resulted fivefold decrease ability as assessed by competition assays. These had no detectable...

The Mycobacterium tuberculosis genome encodes two complete high-affinity Pst phosphate-specific transporters. We previously demonstrated that a membrane-spanning component of one system, PstA1, was essential both for M. virulence and regulation gene expression in response to external phosphate availability. To determine if the alternative system is similarly required or regulation, we constructed deletion pstA2. Transcriptome analysis revealed PstA2 not phosphate-replete growth conditions....

Many bacteria regulate gene expression in response to phosphate availability using a two-component signal transduction system, the activity of which is controlled by interaction with Pst specific transporter and cytoplasmic protein PhoU. Mycobacterium tuberculosis, causative agent requires its sensing system for virulence antibiotic tolerance, but molecular mechanisms remain poorly characterized. smegmatis serves as model studying mycobacterial pathogens including M. tuberculosis. encodes...