A new pathway for the secretion of virulence factors by bacteria: the flagellar export apparatus functions as a protein-secretion system

Proc Natl Acad Sci U S A. 1999 May 25;96(11):6456-61. doi: 10.1073/pnas.96.11.6456.


Biogenesis of the flagellum, a motive organelle of many bacterial species, is best understood for members of the Enterobacteriaceae. The flagellum is a heterooligomeric structure that protrudes from the surface of the cell. Its assembly initially involves the synthesis of a dedicated protein export apparatus that subsequently transports other flagellar proteins by a type III mechanism from the cytoplasm to the outer surface of the cell, where oligomerization occurs. In this study, the flagellum export apparatus was shown to function also as a secretion system for the transport of several extracellular proteins in the pathogenic bacterium Yersinia enterocolitica. One of the proteins exported by the flagellar secretion system was the virulence-associated phospholipase, YplA. These results suggest type III protein secretion by the flagellar system may be a general mechanism for the transport of proteins that influence bacterial-host interactions.

Publication types

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

MeSH terms

  • Anti-Bacterial Agents / pharmacology
  • Bacterial Proteins / biosynthesis
  • Enterobacteriaceae / pathogenicity*
  • Enterobacteriaceae / physiology*
  • Flagella / physiology*
  • Genes, Bacterial
  • Movement / drug effects
  • Movement / physiology
  • Mutagenesis
  • Phospholipases / genetics
  • Phospholipases / metabolism*
  • Regulon
  • Virulence
  • Yersinia enterocolitica / genetics
  • Yersinia enterocolitica / pathogenicity*
  • Yersinia enterocolitica / physiology*


  • Anti-Bacterial Agents
  • Bacterial Proteins
  • Phospholipases