InvB is a type III secretion chaperone specific for SspA.

Journal Article (Journal Article)

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.

Full Text

Duke Authors

Cited Authors

  • Bronstein, PA; Miao, EA; Miller, SI

Published Date

  • December 2000

Published In

Volume / Issue

  • 182 / 23

Start / End Page

  • 6638 - 6644

PubMed ID

  • 11073906

Pubmed Central ID

  • PMC111404

Electronic International Standard Serial Number (EISSN)

  • 1098-5530

International Standard Serial Number (ISSN)

  • 0021-9193

Digital Object Identifier (DOI)

  • 10.1128/jb.182.23.6638-6644.2000


  • eng