Inactivation of macrophage Rab7 by Burkholderia cenocepacia

J Innate Immun. 2010;2(6):522-33. doi: 10.1159/000319864. Epub 2010 Sep 10.

Abstract

Strains of the Burkholderia cepacia complex can survive within macrophages by arresting the maturation of phagocytic vacuoles. The bacteria preclude fusion of the phagosome with lysosomes by a process that is poorly understood. Using murine macrophages, we investigated the stage at which maturation is arrested and analyzed the underlying mechanism. Vacuoles containing B. cenocepacia strain J2315, an isolate of the transmissible ET12 clone, recruited Rab5 and synthesized phosphatidylinositol-3-phosphate, indicating progression to the early phagosomal stage. Despite the fact that the B. cenocepacia-containing vacuoles rarely fused with lysosomes, they could nevertheless acquire the late phagosomal markers CD63 and Rab7. Fluorescence recovery after photobleaching and use of a probe that detects Rab7-guanosine triphosphate indicated that activation of Rab7 was impaired by B. cenocepacia, accounting at least in part for the inability of the vacuole to merge with lysosomes. The Rab7 defect was not due to excessive cholesterol accumulation and was confined to the infected vacuoles. Jointly, these experiments indicate that B. cenocepacia express virulence factors capable of interfering with Rab7 function and thereby with membrane traffic.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, CD / genetics
  • Antigens, CD / metabolism
  • Antigens, Differentiation / genetics
  • Antigens, Differentiation / metabolism
  • Burkholderia Infections / immunology*
  • Burkholderia Infections / microbiology
  • Burkholderia cenocepacia / pathogenicity
  • Burkholderia cenocepacia / physiology*
  • Cell Line
  • Cloning, Molecular
  • Guanosine Triphosphate / metabolism
  • Humans
  • Macrophages / immunology
  • Macrophages / metabolism*
  • Macrophages / microbiology
  • Macrophages / pathology
  • Membrane Fusion / immunology
  • Mice
  • Phagosomes / microbiology
  • Phagosomes / physiology*
  • Platelet Membrane Glycoproteins / genetics
  • Platelet Membrane Glycoproteins / metabolism
  • Tetraspanin 30
  • Virulence Factors
  • rab GTP-Binding Proteins / genetics
  • rab GTP-Binding Proteins / immunology
  • rab GTP-Binding Proteins / metabolism*
  • rab7 GTP-Binding Proteins

Substances

  • Antigens, CD
  • Antigens, Differentiation
  • CD63 protein, human
  • Cd63 protein, mouse
  • Platelet Membrane Glycoproteins
  • Tetraspanin 30
  • Virulence Factors
  • rab7 GTP-Binding Proteins
  • rab7 GTP-binding proteins, human
  • rab7 GTP-binding proteins, mouse
  • Guanosine Triphosphate
  • rab GTP-Binding Proteins