The type III secretion determinants of the flagellar anti-transcription factor, FlgM, extend from the amino-terminus into the anti-sigma28 domain

1998 ◽  
Vol 30 (5) ◽  
pp. 1029-1040 ◽  
Author(s):  
Gavin S. Chilcott ◽  
Kelly T. Hughes
Keyword(s):  
Transcription Factor ◽  
Type Iii Secretion ◽  
Amino Terminus ◽  
Type Iii

scholarly journals LuxT is a Global Regulator of Low-Cell Density Behaviors Including Type III Secretion, Siderophore Production, and Aerolysin Secretion in Vibrio harveyi

2021 ◽  
Author(s):  
Michaela J. Eickhoff ◽  
Chenyi Fei ◽  
Jian-Ping Cong ◽  
Bonnie L. Bassler
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Cell Density ◽  
Type Iii Secretion ◽  
Siderophore Production ◽  
Communication Process ◽  
Global Regulator ◽  
Type Iii ◽  
Regulatory Cascade ◽  
Low Cell Density

Quorum sensing (QS) is a chemical communication process in which bacteria produce, release, and detect extracellular signaling molecules called autoinducers. Via combined transcriptional and post-transcriptional regulatory mechanisms, QS allows bacteria to collectively alter gene expression on a population-wide scale. Recently, the LuxT transcription factor was shown to control V. harveyiqrr1, encoding the Qrr1 small RNA that functions at the core of the QS regulatory cascade. Here, we use RNA-Sequencing to reveal that, beyond control of qrr1, LuxT is a global regulator of 414 V. harveyi genes including those involved in type III secretion, siderophore production, and aerolysin toxin biosynthesis. Importantly, LuxT directly represses swrZ, encoding a transcription factor, and LuxT control of type III secretion, siderophore, and aerolysin genes occurs by two mechanisms, one that is SwrZ-dependent and one that is SwrZ-independent. All of these target genes specify QS-controlled behaviors that are enacted when V. harveyi is at low cell density. Thus, LuxT and SwrZ function in parallel with QS to drive particular low cell density behaviors. Phylogenetic analyses reveal that luxT is highly conserved among Vibrionaceae, but swrZ is less well conserved. In a test case to examine the relationship between LuxT and SwrZ, we find that in Aliivibrio fischeri, LuxT also functions as a swrZ repressor, and LuxT activates A. fischeri siderophore production via swrZ repression. Our results indicate that LuxT is a major regulator among Vibrionaceae, and, in the species that also possess swrZ, LuxT functions with SwrZ to control gene expression.

scholarly journals InvB Is a Type III Secretion Chaperone Specific for SspA

2000 ◽  
Vol 182 (23) ◽  
pp. 6638-6644 ◽  
Author(s):  
Philip A. Bronstein ◽  
Edward A. Miao ◽  
Samuel I. Miller
Keyword(s):  
Protein Interactions ◽  
Type Iii Secretion ◽  
Effector Proteins ◽  
Amino Terminus ◽  
Protein Protein Interactions ◽  
Type Iii ◽  
Protein Levels ◽  
Serovar Typhimurium ◽  
Secretion Chaperone ◽  
Bacterial Cytoplasm

ABSTRACT A wide variety of gram-negative bacteria utilize a specialized apparatus called the type III secretion system (TTSS) to translocate virulence factors directly into the cytoplasm of eukaryotic cells. These translocated effectors contribute to the pathogen's ability to infect and replicate within plant and animal hosts. The amino terminus of effector proteins contains sequences that are necessary and sufficient for both secretion and translocation by TTSS. Portions of these sequences contain binding sites for type III chaperones, which facilitate efficient secretion and translocation of specific effectors through TTSS. In this study, we have utilized the yeast two-hybrid assay to identify protein-protein interactions between effector and chaperone proteins encoded within Salmonella pathogenicity island 1 (SPI-1). Several interactions were identified including a novel interaction between the effector protein, SspA (SipA), and a putative chaperone, InvB. InvB was demonstrated to bind to the amino terminus of SspA in the bacterial cytoplasm. Furthermore, InvB acts as a type III chaperone for the efficient secretion and translocation of SspA by SPI-1. InvB also permitted translocation of SspA through the SPI-2 TTSS, indicating that it is an important regulator in the recognition of SspA as a target of TTSS. Finally, it was determined that InvB does not alter the transcription of sspA but that its absence results in reduced SspA protein levels in Salmonella enterica serovar Typhimurium.

scholarly journals Effector ExoU from the Type III Secretion System Is an Important Modulator of Gene Expression in Lung Epithelial Cells in Response to Pseudomonas aeruginosa Infection

2003 ◽  
Vol 71 (10) ◽  
pp. 6035-6044 ◽  
Author(s):  
B. McMorran ◽  
L. Town ◽  
E. Costelloe ◽  
J. Palmer ◽  
J. Engel ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Transcription Factor ◽  
Epithelial Cells ◽  
Type Iii Secretion ◽  
Lung Epithelial Cells ◽  
Type Iii ◽  
Lung Epithelial ◽  
Factor C ◽  
Host Genes

ABSTRACT Pseudomonas aeruginosa is an important pathogen in immunocompromised patients and secretes a diverse set of virulence factors that aid colonization and influence host cell defenses. An important early step in the establishment of infection is the production of type III-secreted effectors translocated into host cells by the bacteria. We used cDNA microarrays to compare the transcriptomic response of lung epithelial cells to P. aeruginosa mutants defective in type IV pili, the type III secretion apparatus, or in the production of specific type III-secreted effectors. Of the 18,000 cDNA clones analyzed, 55 were induced or repressed after 4 h of infection and could be classified into four different expression patterns. These include (i) host genes that are induced or repressed in a type III secretion-independent manner (32 clones), (ii) host genes induced specifically by ExoU (20 clones), and (iii) host genes induced in an ExoU-independent but type III secretion dependent manner (3 clones). In particular, ExoU was essential for the expression of immediate-early response genes, including the transcription factor c-Fos. ExoU-dependent gene expression was mediated in part by early and transient activation of the AP1 transcription factor complex. In conclusion, the present study provides a detailed insight into the response of epithelial cells to infection and indicates the significant role played by the type III virulence mechanism in the initial host response.

scholarly journals Hfq and sRNA 179 Inhibit Expression of the Pseudomonas aeruginosa cAMP-Vfr and Type III Secretion Regulons

mBio ◽  
2020 ◽  
Vol 11 (3) ◽  
Author(s):  
Kayley H. Janssen ◽  
Jodi M. Corley ◽  
Louise Djapgne ◽  
J. T. Cribbs ◽  
Deven Voelker ◽  
...  
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Transcription Factor ◽  
Type Iii Secretion ◽  
Noncoding Rnas ◽  
Secretion System ◽  
Expression Library ◽  
Content Type ◽  
Type Iii ◽  
Small Noncoding Rnas

ABSTRACT Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen causing skin and soft tissue, respiratory, and bloodstream infections. The type III secretion system (T3SS) is one important virulence factor. Production of the T3SS is controlled by ExsA, a transcription factor that activates expression of the entire T3SS regulon. Global regulators including Vfr, RsmA, and Hfq also contribute to regulation of the T3SS. Vfr is a cAMP-responsive transcription factor that activates exsA transcription. RsmA, an RNA-binding protein, inversely controls expression of the T3SS and the type VI secretion system (T6SS). Hfq is an RNA chaperone that functions by stabilizing small noncoding RNAs (sRNAs) and/or facilitating base pairing between sRNAs and mRNA targets. A previous study identified sRNA 1061, which directly targets the exsA mRNA and likely inhibits ExsA synthesis. In this study, we screened an sRNA expression library and identified sRNA 179 as an Hfq-dependent inhibitor of T3SS gene expression. Further characterization revealed that sRNA 179 inhibits the synthesis of both ExsA and Vfr. The previous finding that RsmA stimulates ExsA and Vfr synthesis suggested that sRNA 179 impacts the Gac/Rsm system. Consistent with that idea, the inhibitory activity of sRNA 179 is suppressed in a mutant lacking rsmY and rsmZ, and sRNA 179 expression stimulates rsmY transcription. RsmY and RsmZ are small noncoding RNAs that sequester RsmA from target mRNAs. Our combined findings show that Hfq and sRNA 179 indirectly regulate ExsA and Vfr synthesis by reducing the available pool of RsmA, leading to reduced expression of the T3SS and cAMP-Vfr regulons. IMPORTANCE Control of gene expression by small noncoding RNA (sRNA) is well documented but underappreciated. Deep sequencing of mRNA preparations from Pseudomonas aeruginosa suggests that >500 sRNAs are generated. Few of those sRNAs have defined roles in gene expression. To address that knowledge gap, we constructed an sRNA expression library and identified sRNA 179 as a regulator of the type III secretion system (T3SS) and the cAMP-Vfr regulons. The T3SS- and cAMP-Vfr-controlled genes are critical virulence factors. Increased understanding of the signals and regulatory mechanisms that control these important factors will enhance our understanding of disease progression and reveal potential approaches for therapeutic intervention.

scholarly journals The transcription factor IscR promotes Yersinia type III secretion system activity by antagonizing the repressive H-NS-YmoA histone-like protein complex

2021 ◽  
Author(s):  
David Balderas ◽  
Pablo Alvarez ◽  
Mané Ohanyan ◽  
Erin Mettert ◽  
Natasha Tanner ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Protein Complex ◽  
Type Iii Secretion ◽  
Defense Mechanisms ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Type Iii ◽  
Transcription In Vitro

The type III secretion system (T3SS) is a appendage used by many bacterial pathogens, such as pathogenic Yersinia, to subvert host defenses. However, because the T3SS is energetically costly and immunogenic, it must be tightly regulated in response to environmental cues to enable survival in the host. Here we show that expression of the Yersinia Ysc T3SS master regulator, LcrF, is orchestrated by the opposing activities of the repressive YmoA/H-NS histone-like protein complex and induction by the iron and oxygen-regulated IscR transcription factor. Although IscR has been shown to bind the lcrF promoter and is required for in vivo expression of lcrF, in this study we show IscR alone fails to enhance lcrF transcription in vitro. Rather, we find that in a ymoA mutant, IscR is no longer required for LcrF expression or T3SS activity. Additionally, a mutation in YmoA that prevents H-NS binding (ymoAD43N) rescues the T3SS defect of a ∆iscR mutant, suggesting that a YmoA/H-NS complex is needed for this repressive activity. Furthermore, chromatin immunoprecipitation analysis revealed that H-NS is enriched at the lcrF promoter at environmental temperatures, while IscR is enriched at this promoter at mammalian body temperature under aerobic conditions. Importantly, CRISPRi knockdown of H-NS leads to increased lcrF transcription. Collectively, our data suggest that as IscR levels rise with iron limitation and oxidative stress, conditions Yersinia experiences during extraintestinal infection, IscR antagonizes YmoA/H-NS-mediated repression of lcrF transcription to drive T3SS activity and manipulate host defense mechanisms.

scholarly journals InvBIs a Type III Secretion-Associated Chaperone for theSalmonella enterica Effector ProteinSopE

2003 ◽  
Vol 185 (24) ◽  
pp. 7279-7284 ◽  
Author(s):  
Sang Ho Lee ◽  
Jorge E. Galán
Keyword(s):  
Western Blotting ◽  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Eukaryotic Cells ◽  
Amino Terminus ◽  
Effector Protein ◽  
Western Blotting Analysis ◽  
Type Iii ◽  
Serovar Typhimurium

ABSTRACT SopE is a bacteriophage-encoded effector protein of Salmonella enterica serovar Typhimurium that is translocated into the cytosol of eukaryotic cells by a type III secretion system (TTSS) (W.-D. Hardt, H. Urlaub, and J. E. Galán, Proc. Natl. Acad. Sci. USA 95:2574-2579, 1998; M. W. Wood, R. Rosqvist, P. B. Mullan, M. H. Edwards, and E. E. Galyov, Mol. Microbiol. 22:327-338, 1996). In this study, we provide evidence that an unlinked gene carried within the Salmonella pathogenicity island 1 (SPI-1), invB (K. Eichelberg, C. Ginocchio, and J. E. Galán, J. Bacteriol. 176:4501-4510, 1994), is required for the secretion of SopE through the SPI-1 TTSS. Furthermore, far-Western blotting analysis shows that SopE directly interacts with InvB through a domain located at its amino terminus. We conclude that InvB is the TTSS-associated chaperone for SopE.

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