EspFU is a translocated EHEC effector that interacts with Tir and N-WASP and promotes Nck-independent actin assembly.
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.
Department of Molecular Genetics and Microbiology, University of Massachusetts Medical School, 55 Lake Avenue North, Worcester 01655 USA.
Kenneth G
KG
Campellone
Douglas
D
Robbins
John M
JM
Leong
D000199:Actins / Q000737:chemistry / Q000378:metabolism; D048868:Adaptor Proteins, Signal Transducing; D015153:Blotting, Western; D002352:Carrier Proteins / Q000378:metabolism / Q000502:physiology*; D002467:Cell Nucleus / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism; D019453:Escherichia coli O157 / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism* / Q000502:physiology*; D017353:Gene Deletion; D005816:Genetic Complementation Test; D044404:Genomic Islands; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D047908:Intracellular Signaling Peptides and Proteins; D008856:Microscopy, Fluorescence; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D015513:Oncogene Proteins / Q000378:metabolism*; D019000:Phosphotyrosine / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011392:Proline / Q000737:chemistry; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D011956:Receptors, Cell Surface / Q000378:metabolism*; D013347:Subcellular Fractions; D020798:Two-Hybrid System Techniques; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal
D000199:Actins; D048868:Adaptor Proteins, Signal Transducing; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; C489109:EspFU protein, E coli; D047908:Intracellular Signaling Peptides and Proteins; C078332:Nck protein; D009419:Nerve Tissue Proteins; D015513:Oncogene Proteins; D011956:Receptors, Cell Surface; C109287:Tir protein, E coli; C495771:WASL protein, human; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal; D019000:Phosphotyrosine; D011392:Proline