The Salmonella SpiC protein targets the mammalian Hook3 protein function to alter cellular trafficking

Mol Microbiol. 2003 Sep;49(6):1565-76. doi: 10.1046/j.1365-2958.2003.03668.x.

Abstract

The Salmonella SpiC protein is secreted into the cytosol of macrophages via a unique type III secretion system that functions intracellularly to translocate proteins across the phagosomal membrane. The SpiC protein is required for survival within macrophages and inhibition of phagosome-lysosome fusion in vivo, and it is sufficient to inhibit endosome-endosome fusion in vitro. Here, we establish that SpiC targets the function of Hook3, a mammalian protein implicated in cellular trafficking. Purified GST-SpiC pulled down Hook3 from murine macrophages, and anti-Hook3 antibodies precipitated SpiC from the cytosol of Salmonella-infected macrophages. Expression of the spiC gene disrupted Golgi morphology in Vero cells and altered the distribution of lysosomes in macrophages, mimicking the phenotype of cells expressing a hook3 dominant-negative mutant. By inactivating Hook3 function, the SpiC protein may alter the lysosome network and prevent phagosome-lysosome fusion.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Bacterial Proteins / genetics
  • Bacterial Proteins / isolation & purification
  • Bacterial Proteins / metabolism*
  • Cell Line
  • Cyclic AMP / metabolism
  • Genes, Reporter
  • Lysosomes / metabolism*
  • Macrophages / metabolism
  • Macrophages / microbiology*
  • Mice
  • Microscopy, Fluorescence
  • Microtubule-Associated Proteins / chemistry
  • Microtubule-Associated Proteins / isolation & purification
  • Microtubule-Associated Proteins / metabolism*
  • Molecular Sequence Data
  • Phagosomes / metabolism*
  • Protein Binding
  • Protein Transport / physiology
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Salmonella typhimurium / genetics
  • Salmonella typhimurium / metabolism
  • Salmonella typhimurium / pathogenicity*
  • Sequence Homology, Amino Acid

Substances

  • Bacterial Proteins
  • Microtubule-Associated Proteins
  • Recombinant Fusion Proteins
  • SpiC protein, Salmonella
  • hook3 protein, human
  • hook3 protein, mouse
  • Cyclic AMP