[Deletion analysis of the SUP2 gene in Saccharomyces cerevisiae]. / Deletsionnyi analiz gena SUP2 drozhzhei Saccharomyces cerevisiae.

The sup2 mutations of the yeast Saccharomyces cerevisiae or plasmid-mediated amplification of the wild type SUP2 gene lead to suppression of different types of nonsense mutations. The Sup2 protein includes a C-terminal region homologous to elongation factor EF-1 alpha and an unique N-terminal region. The SUP2 is an essential gene. The functional role of different regions of the SUP2 gene was investigated, by deleting them without disruption of the reading frame. Such constructs were maintained in yeast on episomal or centromeric plasmids. It was shown that the region, homologous to EF-1 alpha is necessary for viability, while the remaining N-terminal part is nonessential. The region of the first 154 amino acids is necessary and sufficient for the suppressor effect, caused by plasmid-mediated amplification of the SUP2 gene.

[Comparative analysis of the structure of SUP2 genes in Pichia pinus and Saccharomyces cerevisiae]. / Sravnitel'nyi analiz struktury genov SUP2 drozhzhei Pichia pinus i Saccharomyces cerevisiae.

SUP2(SUP35) is an omnipotent suppressor gene, coding for an EF-1 alpha-like protein factor, involved in the control of translational accuracy in yeast Saccharomyces cerevisiae. A SUP2 gene analogue from yeast Pichia pinus was isolated by complementation of temperature-sensitive sup2 mutation of S. cerevisiae. Nucleotide sequence of the SUP2 gene of P. pinus codes for a protein of 82.4 kDa exceeding the SUP2 protein of S. cerevisiae for 6 kDa. The SUP2 gene product of P. pinus is similar to the Sup2 protein of S. cerevisiae by its structure and includes a highly conservative (76%) C-terminal region homologus to EF-1 alpha and a lowly conservative N-terminal region. The relation between the evolutionary conservativity of different regions of the Sup2 protein and their functional significance is discussed.

[Development of a system of intragenic mapping for molecular genetic analysis of mutations in the gene LYS2 of Saccharomyces yeasts]. / Razrabotka sistemy vnutrigennogo kartirovaniia dlia molekuliarno- geneticheskogo analiza mutatsii v gene LYS2 u drozhzhei sakharomitsetov.

The collection of overlapping lys2 deletions (five in the chromosomal and seven in the plasmid LYS2 gene) is constructed in this work. The deletions overlap the whole coding region of the gene and provide the system for intragenic recombinational mapping of lys2 mutations in one of 14 controlled regions. A portion of these regions can be correlated with the regions on the physical map of LYS2. Mutations in two regions can be easily cloned. The system constructed gives the possibility for the study of intragenic and molecular specificity of mutagenesis.

[Genetic analysis of spontaneous and 6-N-hydroxylaminopurine and propiolactone induced Adp+ mutants in Saccharomyces yeasts]. / Geneticheskii analiz spontannykh i indutsirovannykh 6-N-gidroksilaminpurinom i propiolaktonom mutantov Adp+ u drozhzhei sakharomitsetov.

652 spontaneous and 6-N-hydroxylaminopurine and propiolactone-induced mutants were obtained in yeast. 598 of them were LYS2 mutants. Detailed genetic analysis of the mutants was performed, including analysis of growth pattern on lysineless medium, suppressibility by nonsense suppressors of three types and localization on the recombination map of the LYS2 gene. Mutants induced by different agents were different for all these criteria, except for distribution among the map regions.

[Mutability of LYS2 gene in diploid Saccharomyces yeasts. II. Frequency of mutants induced by 6-N-hydroxylaminopurine and propiolactone]. / Izuchenie mutabil'nosti gena LES2 u diploidov drozhzhei sakharomitsetov. Soobshchenie II. Vozniknovenie mutantov, indutsirovannykh 6-N-gidroksilaminopurinom i propiolaktonom.

Chemical mutagens 6-N-hydroxylaminopurine (HAP) and propiolactone (PRO) induce Lys2 mutants with high frequency in diploid yeast Saccharomyces cerevisiae. HAP induces such mutants even in tetraploid strains. The genetic analysis of mutants was performed. It is shown that PRO induces mutants by means of "mutation-mitotic segregation" mechanism, while HAP induces mutants through novel mechanism "both allele mutation". Manifestation of such mechanism is the null fertility after meiosis of diploid mutants induced by HAP.

[Phenotypic manifestations of yeast transposon insertion in the LYS2 gene and deletions resulting from imprecise excision of the transposon]. / Fenotipicheskoe proiavlenie insertsii drozhzhevogo transpozona v gene LYS2 i deletsii, voznikaiushchikh pri netochnom vyrezanii transpozona.

The lys2-32 mutant allele resulted from Ty1 element insertion was identified and cloned. The expression and reversions of lys2-32 localized in an autonomous plasmid were studied. The insertion was shown to inactivate LYS2 gene incompletely. Spontaneous reversions to complete or almost complete prototrophy were also obtained. About 50% of revertants retained the insertion. Others arise as a result of imprecise excision events leading to deletions of adjacent LYS2 sequences.

[Mutability of the LYS2 gene in diploid saccharomycete yeasts. I. The occurrence of spontaneous mutants and mutants induced by x-ray and ultraviolet radiation]. / Izuchenie mutabil'nosti gena LYS2 u diploidov drozhzhei sakharomitsetov. Soobshchenie I. Vozniknovenie spontannykh mutantov i mutantov, indutsirovannykh rentgenovskim i ul'trafioletovym izlucheniem.

More than 3000 spontaneous and induced lys2 mutants were obtained in haploid and diploid strains of yeast Saccharomyces. The ability to utilize alpha-aminoadipate was used for lys2 mutant screening. The spontaneous and induced mutation rates were measured in haploid and diploid strains. Mitotic segregation of pho1 marker linked to LYS2 was studied in lys2 mutants obtained in diploid strains. Fertility of diploid lys2 mutants was tested. The conclusion to be drawn from the data presented is that mutations appeared in one of two homologous chromosomes and then segregated by mitotic homozygotization.