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Isolation and characterization of Saccharomyces cerevisiae mutants supersensitive to G1 arrest by the mating hormone a-factor


Nine independent mutants which are supersensitive (ssl ) to G1 arrest by the mating hormone a-factor were isolated by screening mutagenized Saccharomyces cerevisiae MATα cells on solid medium for increased growth inhibition with a-factor. These mutants carried lesions in two complementation groups, ssl1 and ssl2. Mutations at the ssl1 locus were mating type specific: MATα ssl1 cells were supersensitive to α-factor but MATα ssl1 were not supersensitive to α-factor. In contrast, mutations at the ssl2. locus conferred supersensitivity to the mating hormone of the opposite mating type on both MATα, and MATa cells. The α-cell specific capacity to inactivate externally added a-factor was shown to be lacking in MATα ssl1 mutants whereas MATα ssl2. cells were able to inactivate a-factor. Complementation analysis showed that ssl2 and sst2, a mutation originally isolated as conferring supersensitivity to α-factor to MATa cells, are lesions in the same gene. The ssl1 gene was mapped 30.5 centi-Morgans distal to ilv5 on chromosome XII.

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Correspondence to Wolfgang Duntze.

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Communicated by W. Gajewski

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Steden, M., Betz, R. & Duntze, W. Isolation and characterization of Saccharomyces cerevisiae mutants supersensitive to G1 arrest by the mating hormone a-factor. Mol Gen Genet 219, 439–444 (1989).

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Key words

  • Saccharomyces cerevisiae
  • a-factor
  • Conjugation
  • G1 arrest
  • ssl mutations