[Molecular polymorphism of IB-fructosidase SUC genes in the yeast]

SUC gees encoding bea-fructosidase has been investigated in the yeast genus Saccharomyces. We have determined nucleotide sequences of subtelomeric SUC3, SUCS, SUC7, SUC8, SUC9, S UCO10 genes of S. cerevisiae and SUCa gene o:f S. arboricola. Comparisns of nucleotid sequences of all known SUCgenes revealed predominance of transitions C-->T in the third codon position, Which are silent. The amilioacids sequences of p-fructosidases studied have identity of 88-100%.4'Most divergent are SUCa (S.'arboricola) and SUCb (S. bayanus), having amino acid identity.with the other SUCproteins less than 92%. It wasdetermined that accumulation of the polymeric SUC genes takes place in industrial populations of S. cerevisiae, while the other Saccharomyces species (S. arboricola, S.:bayanus, S. cariocanuis, kudriavzevii, S. mikatae and S. paradoxus) each harbor only one SUCgene. Subtelomeric repeats of pructosidase SUCgenes cobetald appear in the genome of S. cerevisiae under the effect of selection in the course of their domestication.