A novel mechanism for covalent attachment of fatty acid to SV40 large T antigen.
The plasma membrane associated subclass of simian virus 40 large T antigen is specifically acylated with palmitic acid in vivo. To further analyze possible biological functions of fatty acid acylation, we developed a target-bound cell free in vitro acylation assay, in which immunopurified large T, bound to protein A-sepharose, was incubated with [3H]fatty acid. In this assay, large T was efficiently labeled with [3H]palmitic acid, but not with [3H]myristic acid. Thus the specificity of the in vivo labeling was preserved in vitro, too. The specific acylation of large T in vitro seemed to occur by an autocatalytic reaction, since it was found to be independent of added acyltransferases and exogenous energy. The energy for this reaction must be provided by the large T molecule itself, probably by an energy-rich internal ester bond. Our results provide evidence for a novel mechanism for the covalent attachment of fatty acids to proteins, which might also operate in vivo.
Walser
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A
Heinrich-Pette-Institut Experimentelle Virologie und Immunologie, Universität Hamburg, Federal Republic of Germany.
Deppert
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W
D000215:Acylation; D000952:Antigens, Polyomavirus Transforming / Q000378:metabolism*; D005227:Fatty Acids / Q000378:metabolism*; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000378:metabolism
D000952:Antigens, Polyomavirus Transforming; D005227:Fatty Acids; D010169:Palmitic Acids; D019308:Palmitic Acid