A Brucella abortus cstA mutant is defective for association with endoplasmic reticulum exit sites and displays altered trafficking in HeLa cells

Microbiology. 2012 Oct;158(Pt 10):2610-2618. doi: 10.1099/mic.0.060509-0. Epub 2012 Jul 19.

Abstract

Members of the genus Brucella are facultative intracellular pathogenic bacteria able to control maturation of their vacuoles. In several cell types, Brucella is able to reach a proliferation compartment derived from the endoplasmic reticulum (ER). Since ER exit site (ERES) functions are required for Brucella proliferation, we performed a yeast two-hybrid screen between human ERES-associated proteins and the predicted brucella proteome. This screening led to the identification of CstA, a conserved protein that specifically interacts with Sec24A, a component of the ERES. We found that a tagged CstA is secreted in Brucella abortus culture medium. This secretion is independent of the type IV secretion system VirB and the flagellum, suggesting that CstA is secreted through another system. We also discovered that a B. abortus cstA mutant is impaired for its association with the Sec23 ERES marker. The B. abortus cstA mutant displayed peculiar trafficking, with reduced association with LAMP1 and Calnexin 12 h post-infection in HeLa cells. However, its intracellular proliferation kinetics was not affected. The data reported here suggest that CstA could be directly or indirectly involved in the control of B. abortus intracellular trafficking in HeLa cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Brucella abortus / metabolism
  • Brucella abortus / pathogenicity*
  • Endoplasmic Reticulum / metabolism*
  • Epithelial Cells / microbiology*
  • HeLa Cells
  • Host-Pathogen Interactions
  • Humans
  • Mutation*
  • Protein Transport*
  • Proteome
  • Two-Hybrid System Techniques
  • Vesicular Transport Proteins / metabolism

Substances

  • Bacterial Proteins
  • Proteome
  • SEC24A protein, human
  • Vesicular Transport Proteins