Real-time imaging of type III secretion: Salmonella SipA injection into host cells

Proc Natl Acad Sci U S A. 2005 Aug 30;102(35):12548-53. doi: 10.1073/pnas.0503407102. Epub 2005 Aug 17.

Abstract

Many pathogenic and symbiotic Gram-negative bacteria employ type III secretion systems to inject "effector" proteins into eukaryotic host cells. These effectors manipulate signaling pathways to initiate symbiosis or disease. By using time-lapse microscopy, we have imaged delivery of the Salmonella type III effector protein SipA/SspA into animal cells in real time. SipA delivery mostly began 10-90 sec after docking and proceeded for 100-600 sec until the bacterial SipA pool (6 +/- 3 x 10(3) molecules) was exhausted. Similar observations were made for the effector protein SopE. This visualization of type III secretion in real time explains the efficiency of host cell manipulation by means of this virulence system.

MeSH terms

  • Adhesins, Bacterial / genetics
  • Adhesins, Bacterial / physiology
  • Animals
  • Bacterial Proteins / genetics
  • Bacterial Proteins / physiology*
  • Base Sequence
  • Biological Transport, Active
  • COS Cells
  • Chlorocebus aethiops
  • DNA, Bacterial / genetics
  • Genes, Bacterial
  • Kinetics
  • Microfilament Proteins / genetics
  • Microfilament Proteins / physiology*
  • Microscopy, Fluorescence
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Salmonella typhimurium / genetics
  • Salmonella typhimurium / pathogenicity
  • Salmonella typhimurium / physiology*
  • Virulence / physiology

Substances

  • Adhesins, Bacterial
  • Bacterial Proteins
  • DNA, Bacterial
  • Microfilament Proteins
  • Recombinant Fusion Proteins
  • SipA protein, Salmonella
  • SspA protein, bacteria