title: Polyomavirus middle-T antigen associates with the kinase domain of Src-related tyrosine kinases.
abstract: Middle-T antigen of mouse polyomavirus, an oncogenic DNA virus, associates with and activates the cellular tyrosine kinases c-Src, c-Yes, and Fyn. This interaction is essential for polyomavirus-mediated transformation of cells in culture and tumor formation in animals. To determine the domain of c-Src directing association with middle-T, mutant c-Src proteins lacking the amino-terminal unique domain and the myristylation signal, the SH2 domain, the SH3 domain, or all three of these domains were coexpressed with middle-T in NIH 3T3 cells. All mutants were found to associate with middle-T, demonstrating that the kinase domain of c-Src, including the carboxy-terminal regulatory tail, is sufficient for association with middle-T. Moreover, we found that Hck, another member of the Src kinase family, does not bind middle-T, while chimeric kinases consisting of the amino-terminal domains of c-Src fused to the kinase domain of Hck or the amino-terminal domains of Hck fused to the kinase domain of c-Src associated with middle-T. Hck mutated at its carboxy-terminal regulatory residue, tyrosine 501, was also found to associate with middle-T. These results suggest that in Hck, the postulated intramolecular interaction between the carboxy-terminal regulatory tyrosine and the SH2 domain prevents association with middle-T. This intramolecular interaction apparently also limits the ability of c-Src to associate with middle-T, since removal of the SH2 or SH3 domain increases the efficiency with which middle-T binds c-Src.
authors.affiliation: Friedrich Miescher Institute, Basel, Switzerland.
authors.forename: N M
authors.initials: NM
authors.lastname: Dunant
authors.forename: M
authors.initials: M
authors.lastname: Senften
authors.forename: K
authors.initials: K
authors.lastname: Ballmer-Hofer
mesh_terms: D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D000952:Antigens, Polyomavirus Transforming / Q000378:metabolism*; D001665:Binding Sites; D000081247:CSK Tyrosine-Protein Kinase; D002645:Chickens; D004789:Enzyme Activation; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051572:Proto-Oncogene Proteins c-hck; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013329:Structure-Activity Relationship; D018909:src Homology Domains; D019061:src-Family Kinases / Q000378:metabolism*
chemical_list: D000952:Antigens, Polyomavirus Transforming; D011518:Proto-Oncogene Proteins; D011993:Recombinant Fusion Proteins; D011505:Protein-Tyrosine Kinases; D000081247:CSK Tyrosine-Protein Kinase; C496631:HCK protein, human; C496632:Hck protein, mouse; D051572:Proto-Oncogene Proteins c-hck; D019061:src-Family Kinases; C000631346:CSK protein, human