SIMPLE IDENTIFICATION OF DOMINANT P53 MUTANTS BY A YEAST FUNCTIONAL ASSAY

Analysis of families with germline p53 mutations shows that the mutant p53 allele behaves as a dominant oncogene at the genetic level, altho ugh it behaves as a recessive oncogene at the cellular level, since tu mours invariably show mutation or loss of both wild-type alleles, At t he biochemical level it is possible that some clinically important mut ant p53 proteins may be carcinogenic through a dominant mechanism, We show that p53 mutants can be readily classified according to their dom inant potential using a simple yeast functional assay, Wild-type p53 i s constitutively expressed from a TRP1 vector, p53 mutants are express ed from an otherwise identical LEU2 vector and net transcriptional act ivity is scored using an ADE2-based reporter, Twenty seven p53 mutants were tested: 19 were recessive, i.e. gave white colonies, and eight s howed dominant activity, i.e. gave pink/red colonies, This simple assa y should facilitate studies on p53 dominance.