Control of gene expression by type III secretory activity

Brutinel, Evan D.; Yahr, Timothy L.

doi:10.1016/j.mib.2008.02.010

Cited by 82 publications

(78 citation statements)

References 44 publications

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“…Expression of T3SS genes of P. aeruginosa is tightly controlled by a partner-switching mechanism involving a cascade of regulatory proteins called ExsA, ExsC, ExsD, and ExsE (127). Transcription of T3SS-associated genes is intimately coupled to the state of the T3SS secretory apparatus by the small, T3SS-secreted regulatory factor ExsE (128).…”

Section: P Aeruginosamentioning

confidence: 99%

Regulation of Bacterial Virulence by Csr (Rsm) Systems

Vakulskas

Potts

Babitzke

et al. 2015

Microbiol Mol Biol Rev

287

400

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SUMMARY Most bacterial pathogens have the remarkable ability to flourish in the external environment and in specialized host niches. This ability requires their metabolism, physiology, and virulence factors to be responsive to changes in their surroundings. It is no surprise that the underlying genetic circuitry that supports this adaptability is multilayered and exceedingly complex. Studies over the past 2 decades have established that the CsrA/RsmA proteins, global regulators of posttranscriptional gene expression, play important roles in the expression of virulence factors of numerous proteobacterial pathogens. To accomplish these tasks, CsrA binds to the 5′ untranslated and/or early coding regions of mRNAs and alters translation, mRNA turnover, and/or transcript elongation. CsrA activity is regulated by noncoding small RNAs (sRNAs) that contain multiple CsrA binding sites, which permit them to sequester multiple CsrA homodimers away from mRNA targets. Environmental cues sensed by two-component signal transduction systems and other regulatory factors govern the expression of the CsrA-binding sRNAs and, ultimately, the effects of CsrA on secretion systems, surface molecules and biofilm formation, quorum sensing, motility, pigmentation, siderophore production, and phagocytic avoidance. This review presents the workings of the Csr system, the paradigm shift that it generated for understanding posttranscriptional regulation, and its roles in virulence networks of animal and plant pathogens.

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Section: P Aeruginosamentioning

confidence: 99%

Regulation of Bacterial Virulence by Csr (Rsm) Systems

Vakulskas

Potts

Babitzke

et al. 2015

Microbiol Mol Biol Rev

287

400

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“…The aim of this review is to summarize our current knowledge of the architecture of T3S systems and the control mechanisms underlying T3S in plant-and animal-pathogenic bacteria. For a detailed description of individual proteins or regulatory mechanisms, the reader is also referred to excellent previous overview articles that provide summaries on the following topics: translocation-associated T3S systems (29,72,105,161,199,217,557), flagellar T3S systems (92,161,343,377,428,549), T3S chaperones (175,431), structures and functions of individual components of T3S systems (46,70,243,281,283,349,353,389,395,482), and control mechanisms underlying T3S and gene expression (64,106,129,212,370,421,547,555,588).…”

mentioning

confidence: 99%

Protein Export According to Schedule: Architecture, Assembly, and Regulation of Type III Secretion Systems from Plant- and Animal-Pathogenic Bacteria

Büttner

2012

Microbiol Mol Biol Rev

359

482

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SUMMARY Flagellar and translocation-associated type III secretion (T3S) systems are present in most Gram-negative plant- and animal-pathogenic bacteria and are often essential for bacterial motility or pathogenicity. The architectures of the complex membrane-spanning secretion apparatuses of both systems are similar, but they are associated with different extracellular appendages, including the flagellar hook and filament or the needle/pilus structures of translocation-associated T3S systems. The needle/pilus is connected to a bacterial translocon that is inserted into the host plasma membrane and mediates the transkingdom transport of bacterial effector proteins into eukaryotic cells. During the last 3 to 5 years, significant progress has been made in the characterization of membrane-associated core components and extracellular structures of T3S systems. Furthermore, transcriptional and posttranscriptional regulators that control T3S gene expression and substrate specificity have been described. Given the architecture of the T3S system, it is assumed that extracellular components of the secretion apparatus are secreted prior to effector proteins, suggesting that there is a hierarchy in T3S. The aim of this review is to summarize our current knowledge of T3S system components and associated control proteins from both plant- and animal-pathogenic bacteria.

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“…According to the bacterial metabolism and/or infectious niche, the synthesis of T3SS as well as other virulence factors is finely tuned by general and specific regulatory pathways (10,11). Molecular links between general pathways and T3SS regulation have generally not been identified yet; however, they all converge toward one transcription factor that is absolutely required for T3SS gene expression, the ExsA protein (10 and references therein and Refs.…”

mentioning

confidence: 99%

Anti-activator ExsD Forms a 1:1 Complex with ExsA to Inhibit Transcription of Type III Secretion Operons

Thibault

Faudry

Ebel

et al. 2009

Journal of Biological Chemistry

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The ExsA protein is a Pseudomonas aeruginosa transcriptional regulator of the AraC/XylS family that is responsible for activating the type III secretion system operons upon host cell contact. Its activity is known to be controlled in vivo through interaction with its negative regulator ExsD. Using a heterologous expression system, we demonstrated that ExsD is sufficient to inhibit the transcriptional activity of ExsA. Gel shift assays with ExsA-and ExsD-containing cytosolic extracts revealed that ExsD does not block DNA target sites but affects the DNA binding activity of the transcriptional activator. The ExsA-ExsD complex was purified after coproduction of the two partners in Escherichia coli. Size exclusion chromatography and ultracentrifugation analysis revealed a homogeneous complex with a 1:1 ratio. When in interaction with ExsD, ExsA is not able to bind to its specific target any longer, as evidenced by gel shift assays. Size exclusion chromatography further showed a partial dissociation of the complex in the presence of a specific DNA sequence. A model of the molecular inhibitory role of ExsD toward ExsA is proposed, in which, under noninducing conditions, the anti-activator ExsD sequesters ExsA and hinders its binding to DNA sites, preventing the transcription of type III secretion genes.

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Control of gene expression by type III secretory activity

Cited by 82 publications

References 44 publications

Regulation of Bacterial Virulence by Csr (Rsm) Systems

Regulation of Bacterial Virulence by Csr (Rsm) Systems

Protein Export According to Schedule: Architecture, Assembly, and Regulation of Type III Secretion Systems from Plant- and Animal-Pathogenic Bacteria

Anti-activator ExsD Forms a 1:1 Complex with ExsA to Inhibit Transcription of Type III Secretion Operons

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