Bacterial Secretion Chaperones

Fattori, Juliana; Prando, Alessandra; Martins, Adriana Martini; Rodrigues, F.H. Dos Santos; Tasić, Ljubica

doi:10.2174/092986611794475048

Cited by 12 publications

(8 citation statements)

References 62 publications

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“…These secretion signals are located near the C termini and composed predominantly of positively charged and/or hydrophobic residues. Several of these systems require in addition to the secretion signal an accessory protein (32). Such accessory proteins mainly act as chaperones to help stabilize the fold and prevent aggregation.…”

Section: Discussionmentioning

confidence: 99%

Characterization of the Translocation-competent Complex between the Helicobacter pylori Oncogenic Protein CagA and the Accessory Protein CagF

Bonsor

Weiss

Iosub-Amir

et al. 2013

Journal of Biological Chemistry

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Section: Discussionmentioning

confidence: 99%

Characterization of the Translocation-competent Complex between the Helicobacter pylori Oncogenic Protein CagA and the Accessory Protein CagF

Bonsor

Weiss

Iosub-Amir

et al. 2013

Journal of Biological Chemistry

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“…T3S chaperones are known to selectively regulate and bind to T3S translocator and effector proteins (10). These chaperones have multiple functions, including stabilization of T3S substrates, prevention of premature interactions between substrates through sequestration, and targeting substrates for secretion through the T3S apparatus (10).…”

mentioning

confidence: 99%

“…These chaperones have multiple functions, including stabilization of T3S substrates, prevention of premature interactions between substrates through sequestration, and targeting substrates for secretion through the T3S apparatus (10). T3S chaperones are subdivided into several classes based on their substrate specificity.…”

mentioning

confidence: 99%

Chlamydia trachomatis Type III Secretion Proteins Regulate Transcription

et al. 2015

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The Scc4 protein (CT663) of the pathogenic bacterium Chlamydia has been described as a type III secretion (T3S) chaperone as well as an inhibitor of RNA polymerase. To examine if these roles are connected, we first investigated physical interactions between Chlamydia trachomatis Scc4 and the T3S chaperone Scc1 and a T3S substrate, CopN. In a yeast 3-hybrid assay, Scc4, Scc1, and CopN were all required to detect an interaction, which suggests that these proteins form a trimolecular complex. We also detected interactions between any two of these three T3S proteins in a pulldown assay using only recombinant proteins. We next determined whether these interactions affected the function of Scc4 as an inhibitor of RNA transcription. Using Escherichia coli as a heterologous in vivo system, we demonstrated that expression of C. trachomatis Scc4 led to a drastic decrease in transcript levels for multiple genes. However, coexpression of Scc4 with Scc1, CopN, or both alleviated Scc4-mediated inhibition of transcription. Scc4 expression also severely impaired E. coli growth, but this growth defect was reversed by coexpression of Scc4 with Scc1, CopN, or both, suggesting that the inhibitory effect of Scc4 on transcription and growth can be antagonized by interactions between Scc4, Scc1, and CopN. These findings suggest that the dual functions of Scc4 may serve as a bridge to link T3S and the regulation of gene expression in Chlamydia. IMPORTANCEThis study investigates a novel mechanism for regulating gene expression in the pathogenic bacterium Chlamydia. The Chlamydia type III secretion (T3S) chaperone Scc4 has been shown to inhibit transcription by RNA polymerase. This study describes physical interactions between Scc4 and the T3S proteins Scc1 and CopN. Furthermore, Chlamydia Scc1 and CopN antagonized the inhibitory effects of Scc4 on transcription and growth in a heterologous Escherichia coli system. These results provide evidence that transcription in Chlamydia can be regulated by the T3S system through interactions between T3S proteins. C hlamydia trachomatis is the most prevalent cause of bacterial sexually transmitted infections in the United States (1, 2). In addition, it is the most common cause of preventable blindness in the world (3). Chlamydia is an unusual obligate intracellular bacterium that has two distinct forms, the infectious elementary body (EB) and the noninfectious reticulate body (RB) (4). Once the EB attaches and enters a susceptible host cell, it converts into an RB that replicates by binary fission, generating hundreds of progeny within the membrane-bound chlamydial inclusion.Like other pathogenic Gram-negative bacteria, Chlamydia utilizes a type III secretion (T3S) system to deliver effector proteins into a eukaryotic cell (5). In Chlamydia, T3S is important for a number of steps in the intracellular infection (6). EB entry into the host cell is mediated in part by translocation of the T3S effector protein Tarp, which recruits actin at the site of EB attachment and likely aids in internaliz...

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“…The secretion signal requirements for T3S substrates remains poorly defined, but all substrates utilize an N-terminal peptide secretion signal that is disordered in structure and, unlike the case with type II secretion, is not cleaved during the secretion process (11). Substrate secretion is often facilitated by T3S chaperone-assisted delivery to the secretion apparatus (12). The FlgM protein is 97 amino acids in length, and its secretion is dependent on an N-terminal secretion signal.…”

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confidence: 99%

Analysis of Factors That Affect FlgM-Dependent Type III Secretion for Protein Purification with Salmonella enterica Serovar Typhimurium

et al. 2014

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Conditions known to affect flagellar gene expression, FlgM stability, and flagellar T3S were tested either alone or in combination to determine their effects on levels of secreted FlgM. These conditions included mutations that affect activity of the flagellar FlhD 4 C 2 master regulatory protein complex or the FlgM T3S chaperone 28 , the removal of Salmonella pathogenicity island 1 (Spi1), the removal of flagellar late secretion substrates that could compete with FlgM for secretion, and changes in the ionic strength of the growth medium. Conditions that enhanced FlgM secretion were combined in order to maximize levels of secreted FlgM. An optimized FlgM secretion strain was used to secrete and isolate otherwise difficult-to-produce proteins and peptides fused to the C terminus of FlgM. These include cysteine-rich, hydrophobic peptides (conotoxins ␦-SVIE and MrVIA), nodulespecific, cysteine-rich antimicrobial peptides (NCR), and a malaria surface antigen domain of apical membrane antigen AMA-1.

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Bacterial Secretion Chaperones

Cited by 12 publications

References 62 publications

Characterization of the Translocation-competent Complex between the Helicobacter pylori Oncogenic Protein CagA and the Accessory Protein CagF

Characterization of the Translocation-competent Complex between the Helicobacter pylori Oncogenic Protein CagA and the Accessory Protein CagF

Chlamydia trachomatis Type III Secretion Proteins Regulate Transcription

Analysis of Factors That Affect FlgM-Dependent Type III Secretion for Protein Purification with Salmonella enterica Serovar Typhimurium

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