EspFU is a translocated EHEC effector that interacts with Tir and N-WASP and promotes Nck-independent actin assembly

Dev Cell. 2004 Aug;7(2):217-28. doi: 10.1016/j.devcel.2004.07.004.

Abstract

Several microbial pathogens including enteropathogenic E. coli (EPEC) exploit mammalian tyrosine-kinase signaling cascades to recruit Nck adaptor proteins and activate N-WASP-Arp2/3-mediated actin assembly. To promote localized actin "pedestal formation," EPEC translocates the bacterial effector protein Tir into the plasma membrane, where it is tyrosine-phosphorylated and binds Nck. Enterohemorrhagic E. coli (EHEC) also generates Tir-dependent pedestals, but in the absence of phosphotyrosines and Nck recruitment. To identify additional EHEC effectors that stimulate phosphotyrosine-independent actin assembly, we systematically generated EHEC mutants containing specific deletions in putative pathogenicity-islands. Among 0.33 Mb of deleted sequences, only one ORF was critical for pedestal formation. It lies within prophage-U, and encodes a protein similar to the known effector EspF. This proline-rich protein, EspFU, is the only EHEC effector of actin assembly absent from EPEC. Whereas EHEC Tir cannot efficiently recruit N-WASP or trigger actin polymerization, EspFU associates with Tir, binds N-WASP, and potently stimulates Nck-independent actin assembly.

Publication types

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

MeSH terms

  • Actins / chemistry
  • Actins / metabolism
  • Adaptor Proteins, Signal Transducing
  • Blotting, Western
  • Carrier Proteins / metabolism
  • Carrier Proteins / physiology*
  • Cell Nucleus / metabolism
  • Escherichia coli / metabolism
  • Escherichia coli O157 / metabolism*
  • Escherichia coli Proteins / metabolism*
  • Escherichia coli Proteins / physiology*
  • Gene Deletion
  • Genetic Complementation Test
  • Genomic Islands
  • HeLa Cells
  • Humans
  • Immunoblotting
  • Intracellular Signaling Peptides and Proteins
  • Microscopy, Fluorescence
  • Mutation
  • Nerve Tissue Proteins / metabolism*
  • Oncogene Proteins / metabolism*
  • Phosphotyrosine / chemistry
  • Plasmids / metabolism
  • Precipitin Tests
  • Proline / chemistry
  • Protein Binding
  • Protein Structure, Tertiary
  • Protein Transport
  • Receptors, Cell Surface / metabolism*
  • Subcellular Fractions
  • Two-Hybrid System Techniques
  • Wiskott-Aldrich Syndrome Protein, Neuronal

Substances

  • Actins
  • Adaptor Proteins, Signal Transducing
  • Carrier Proteins
  • Escherichia coli Proteins
  • EspFU protein, E coli
  • Intracellular Signaling Peptides and Proteins
  • Nck protein
  • Nerve Tissue Proteins
  • Oncogene Proteins
  • Receptors, Cell Surface
  • Tir protein, E coli
  • WASL protein, human
  • Wiskott-Aldrich Syndrome Protein, Neuronal
  • Phosphotyrosine
  • Proline