title: Host adaptor proteins Gab1 and CrkII promote InlB-dependent entry of Listeria monocytogenes.
abstract: The bacterial surface protein InlB mediates internalization of Listeria monocytogenes into mammalian cells through interaction with the host receptor tyrosine kinase, Met. InlB/Met interaction results in activation of the host phosphoinositide (PI) 3-kinase p85-p110, an event required for bacterial entry. p85-p110 activation coincides with tyrosine phosphorylation of the host adaptor Gab1, and formation of complexes between Gab1 and the p85 regulatory subunit of PI 3-kinase. When phosphorylated in response to agonists, Gab1 is known to recruit several Src-homology 2 (SH2) domain-containing proteins including p85, the tyrosine phosphatase Shp2 and the adaptor CrkII. Here, we demonstrate that Gab1.p85 and Gab1.CrkII complexes promote entry of Listeria. Overexpression of wild-type Gab1 stimulated entry, whereas Gab1 alleles unable to recruit all SH2 proteins known to bind wild-type Gab1 inhibited internalization. Further analysis with Gab1 alleles defective in binding individual effectors suggested that recruitment of p85 and CrkII are critical for entry. Consistent with this data, overexpression of wild-type CrkII stimulated bacterial uptake. Experiments with mutant CrkII alleles indicated that both the first and second SH3 domains of this adaptor participate in entry, with the second domain playing the most critical role. Taken together, these findings demonstrate novel roles for Gab1 and CrkII in Listeria internalization.
authors.affiliation: Department of Medical Genetics and Microbiology, Faculty of Medicine, University of Toronto, Toronto, Ontario M5S 1A8, Canada.
authors.forename: Hong
authors.initials: H
authors.lastname: Sun
authors.forename: Yang
authors.initials: Y
authors.lastname: Shen
authors.forename: Hatem
authors.initials: H
authors.lastname: Dokainish
authors.forename: Marina
authors.initials: M
authors.lastname: Holgado-Madruga
authors.forename: Albert
authors.initials: A
authors.lastname: Wong
authors.forename: Keith
authors.initials: K
authors.lastname: Ireton
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D002522:Chlorocebus aethiops; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D008089:Listeria monocytogenes / Q000472:pathogenicity / Q000502:physiology*; D009154:Mutation; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D050737:Proto-Oncogene Proteins c-crk; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases; D015398:Signal Transduction; D014709:Vero Cells; D018909:src Homology Domains
chemical_list: D001426:Bacterial Proteins; D047908:Intracellular Signaling Peptides and Proteins; D019869:Phosphatidylinositol 3-Kinases; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases; D011518:Proto-Oncogene Proteins; D050737:Proto-Oncogene Proteins c-crk; D054593:SH2 Domain-Containing Protein Tyrosine Phosphatases