Identification and characterization of a type III secretion-associated chaperone in the type III secretion system 1 of Vibrio parahaemolyticus.
Vibrio parahaemolyticus causes human gastroenteritis. Genomic sequencing of this organism has revealed that it has two sets of type III secretion systems, T3SS1 and T3SS2, both of which are important for its pathogenicity. However, the mechanism of protein secretion via T3SSs is unknown. A characteristic of many effectors is that they require specific chaperones for efficient delivery via T3SSs; however, no chaperone has been experimentally identified in the T3SSs of V. parahaemolyticus. In this study, we identified candidate T3SS1-associated chaperones from genomic sequence data and examined their roles in effector secretion/translocation and binding to their cognate substrates. From these experiments, we concluded that there is a T3S-associated chaperone, VecA, for a cytotoxic T3SS1-dependent effector, VepA. Further analysis using pulldown and secretion assays characterized the chaperone-binding domain encompassing the first 30-100 amino acids and an amino terminal secretion signal encompassing the first 5-20 amino acids on VepA. These findings will provide a strategy to clarify how the T3SS1 of V. parahaemolyticus secretes its specific effectors.
Akeda
Yukihiro
Y
Department of Bacterial Infections, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan. akeda@biken.osaka-u.ac.jp
Okayama
Kanna
K
Kimura
Tomomi
T
Dryselius
Rikard
R
Kodama
Toshio
T
Oishi
Kazunori
K
Iida
Tetsuya
T
Honda
Takeshi
T
D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism; D018832:Molecular Chaperones / Q000235:genetics* / Q000378:metabolism*; D011485:Protein Binding; D025941:Protein Interaction Mapping; D014736:Vibrio parahaemolyticus / Q000235:genetics* / Q000378:metabolism*; D037521:Virulence Factors / Q000378:metabolism
D001426:Bacterial Proteins; D026901:Membrane Transport Proteins; D018832:Molecular Chaperones; D037521:Virulence Factors