Ku70, a component of DNA-dependent protein kinase, is a mammalian receptor for Rickettsia conorii

Cell. 2005 Dec 16;123(6):1013-23. doi: 10.1016/j.cell.2005.08.046.

Abstract

Rickettsia conorii, a strictly intracellular and category C priority bacterial pathogen (NIAID), invades different mammalian cells. Although some signaling events involved in bacterial entry have been documented, the bacterial and host proteins mediating entry were not known. We report the identification of the Ku70 subunit of DNA-dependent protein kinase (DNA-PK) as a receptor involved in R. conorii internalization. Ku70 is recruited to R. conorii entry sites, and inhibition of Ku70 expression impairs R. conorii internalization. Bacterial invasion is dependent on the presence of cholesterol-enriched microdomains containing Ku70. R. conorii infection stimulates the ubiquitination of Ku70. In addition, the ubiquitin ligase c-Cbl is recruited to R. conorii entry foci, and downregulation of endogenous c-Cbl blocks bacterial invasion and Ku70 ubiquitination. An affinity chromatography approach identified the rickettsial protein rOmpB as a ligand for Ku70. This is the first report of a receptor-ligand interaction involved in the internalization of any rickettsial species.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actins / metabolism
  • Animals
  • Antibodies, Monoclonal / pharmacology
  • Antigens, Nuclear / genetics
  • Antigens, Nuclear / immunology
  • Antigens, Nuclear / metabolism*
  • Bacterial Outer Membrane Proteins / metabolism
  • Caveolin 2 / analysis
  • Cell Line
  • Cell Membrane / chemistry
  • Cell Membrane / drug effects
  • Cell Membrane / metabolism
  • Chlorocebus aethiops
  • Cholesterol / metabolism
  • Cholesterol / pharmacology
  • Collagen Type XI / metabolism
  • DNA-Activated Protein Kinase / genetics
  • DNA-Activated Protein Kinase / metabolism
  • DNA-Activated Protein Kinase / physiology
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / immunology
  • DNA-Binding Proteins / metabolism*
  • Endocytosis / drug effects
  • Fibroblasts / microbiology
  • HeLa Cells
  • Humans
  • Ku Autoantigen
  • Membrane Microdomains / chemistry
  • Membrane Microdomains / drug effects
  • Membrane Microdomains / metabolism
  • Mice
  • Mice, Knockout
  • Poly (ADP-Ribose) Polymerase-1
  • Poly(ADP-ribose) Polymerases / metabolism
  • Protein Binding
  • Proto-Oncogene Proteins c-cbl / genetics
  • Proto-Oncogene Proteins c-cbl / metabolism
  • RNA, Small Interfering / genetics
  • Receptors, Cell Surface / genetics
  • Receptors, Cell Surface / metabolism*
  • Rickettsia conorii / metabolism*
  • Ubiquitin / metabolism
  • Vero Cells
  • beta-Cyclodextrins / pharmacology

Substances

  • Actins
  • Antibodies, Monoclonal
  • Antigens, Nuclear
  • Bacterial Outer Membrane Proteins
  • COL11A2 protein, human
  • Caveolin 2
  • Collagen Type XI
  • DNA-Binding Proteins
  • RNA, Small Interfering
  • Receptors, Cell Surface
  • Ubiquitin
  • beta-Cyclodextrins
  • methyl-beta-cyclodextrin
  • Cholesterol
  • Proto-Oncogene Proteins c-cbl
  • Parp1 protein, mouse
  • Poly (ADP-Ribose) Polymerase-1
  • Poly(ADP-ribose) Polymerases
  • DNA-Activated Protein Kinase
  • Xrcc6 protein, human
  • Xrcc6 protein, mouse
  • Ku Autoantigen
  • CBL protein, human