Natural Polymorphism of Pectinase PGU Genes in the Saccharomyces Yeasts

The distribution and properties of the pectinase-encoding PGU genes in different species of Saccharomyces yeasts was studied. Application of molecular karyotyping and Southern hybridization revealed that S. arboricola, S. cariocanus, S. cerevisiae, S. kudriavzevii, and S. paradoxus species had a single PGU gene located on chromosome X. The other three species had polymeric PGU genes of different chromosomal localization: S. mikatae and S. jurei (chromosomes X and VIII), S. bayanus (X, I, and XIV). This is the first report on comparative analysis of the nucleotide and amino acid sequences of the PGU genes was carried out in all eight species of the genus Saccharomyces. Species-specificity of the PGU genes was revealed, as well as their intraspecific polymorphism in S. kudriavzevii and S. paradoxus, associated with the geographical origin of the strains. The most divergent proteins were Pgu1a (S. arboricola) and Pgu1b, Pgu2b, Pgu3b (S. bayanus), for which the level of similarity to the Pgu proteins of other Saccharomyces species did not exceed 89%. The highest similarity (>95%) was noted for the Pgu proteins of S. cerevisiae, S. paradoxus, and S. cariocanus, as well as S. mikatae and S. jurei. Significant intraspecific polymorphism of endo-polygalacturonase secretion was observed in the studied Saccharomyces species, except for the species S. bayanus, all studied strains of which had a relatively high activity. The ability to secrete active endo-polygalacturonase is probably a specific feature of this species.