Human GCIP interacts with CT847, a novel Chlamydia trachomatis type III secretion substrate, and is degraded in a tissue-culture infection model

Blandine Chellas-Géry, Camille N. Linton, Kenneth A. Fields

Research output: Contribution to journalArticle

33 Scopus citations

Abstract

The obligate intracellular bacterium Chlamydia trachomatis occupies a parasitophorous vacuole and employs a type III secretion mechanism to translocate host-interactive proteins. These proteins most likely contribute to pathogenesis through modulation of host cell mechanisms crucial for the establishment and maintenance of a permissive intracellular environment. Using a surrogate Yersinia type III secretion system (T3SS), we have identified the conserved gene product CT847 as a chlamydial T3SS substrate. Yeast two-hybrid studies using CT847 as bait to screen a HeLa cell cDNA library identified an interaction with mammalian G rap2 c yclin D- i nteracting p rotein (GCIP). Immunoblot analyses of C.trachomatis -infected HeLa cells showed that GCIP levels begin to decrease (as compared with mock-infected HeLa cells) between 8h and 12h post infection. GCIP was virtually undetectable in 24h time point material. This decrease was inhibited by proteasome inhibitors lactacystin and MG-132, and the T3SS inhibitor Compound 1. CT847 was detectible in purified reticulate body but not elementary body lysates, and reverse transcription polymerase chain reaction (RT-PCR) expression analyses indicate a mid-cycle expression pattern. Both of these findings are consistent with CT847 contributing to the observed effect on GCIP. Given the established roles of GCIP, we believe that we have discovered a novel C.trachomatis antihost protein whose activity is relevant to chlamydial pathogenesis.

Original languageEnglish (US)
Pages (from-to)2417-2430
Number of pages14
JournalCellular Microbiology
Volume9
Issue number10
DOIs
StatePublished - Oct 1 2007

ASJC Scopus subject areas

  • Microbiology
  • Immunology
  • Virology

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