Sec24 interaction is essential for localization and virulence-associated function of the bacterial effector protein NleA

Cell Microbiol. 2012 Aug;14(8):1206-18. doi: 10.1111/j.1462-5822.2012.01789.x. Epub 2012 Apr 12.


Enteropathogenic and enterohaemorrhagic Escherichia coli (EPEC and EHEC) are food-borne pathogens that cause severe diarrhoeal disease in humans. Citrobacter rodentium is a related mouse pathogen that serves as a small animal model for EPEC and EHEC infections. EPEC, EHEC and C. rodentium translocate bacterial virulence proteins directly into host cells via a type III secretion system (T3SS). Non-LEE-encoded effector A (NleA) is a T3SS effector that is common to EPEC, EHEC and C. rodentium and is required for bacterial virulence. NleA localizes to the host cell secretory pathway and inhibits vesicle trafficking by interacting with the Sec24 subunit of mammalian coatamer protein II complex (COPII). Mammalian cells express four paralogues of Sec24 (Sec24A-D), which mediate selection of cargo proteins for transport and possess distinct, but overlapping cargo specificities. Here, we show that NleA binds Sec24A-D with two distinct mechanisms. An NleA protein variant with greatly diminished interaction with all Sec24 paralogues does not properly localize, does not inhibit COPII-mediated vesicle budding, and does not confer virulence in the mouse infection model. Together, this work provides strong evidence that the interaction and inhibition of COPII by NleA is an important aspect of EPEC- and EHEC-mediated disease.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • COP-Coated Vesicles / microbiology
  • Citrobacter rodentium / metabolism
  • Citrobacter rodentium / physiology*
  • Female
  • HeLa Cells
  • Host-Pathogen Interactions
  • Humans
  • Mice
  • Mice, Inbred C3H
  • PDZ Domains
  • Protein Structure, Quaternary
  • Protein Structure, Secondary
  • Protein Transport
  • Secretory Pathway
  • Sequence Deletion
  • Vesicular Transport Proteins / chemistry
  • Vesicular Transport Proteins / metabolism*
  • Virulence Factors / chemistry
  • Virulence Factors / genetics
  • Virulence Factors / metabolism*


  • Bacterial Proteins
  • SEC24A protein, human
  • SEC24B protein, human
  • SEC24C protein, human
  • SEC24D protein, human
  • Vesicular Transport Proteins
  • Virulence Factors