[Dot1 and Set2 Histone Methylases Control the Spontaneous and UV-Induced Mutagenesis Levels in the Saccharomyces cerevisiae Yeasts].

In the Saccharomyces cerevisiae yeasts, the DOT1 gene product provides methylation of lysine 79 (K79) of hi- stone H3 and the SET2 gene product provides the methylation of lysine 36 (K36) of the same histone. We determined that the dot1 and set2 mutants suppress the UV-induced mutagenesis to an equally high degree. The dot1 mutation demonstrated statistically higher sensitivity to the low doses of MMC than the wild type strain.

[Spontaneous mutation rate changes in saccharomyces cerevisiae at combinations of hsm3 and hsm6 mutations with rad52 mutation].

Long-term storage at +4 degrees C and cultivation at +30 degrees C changes the spontaneous mutation rate of the yeast Saccharomyces cerevisiae double mutants rad52hsm3delta and rad52hsm6-1. Combinations of hsm3 and hsm6 mutations with the rad52 mutation lead to a decrease of the spontaneous mutation rate mediated by DNA repair synthesis in multiply replanted strains in comparison with the same strains investigated right after RAD52 gene decay. Combinations of hsm3 and hsm6 mutations with mutations in other genes of the RAD52 epistatic group did not provide a spontaneous mutation rate decrease.

[Control levels of Sin3 histone deacetylase for spontaneous and UV-induced mutagenesis in yeasts Saccharomyces cerevisiae].

SIN3 gene product operates as a repressor for a huge amount of genes in Saccharomyces cerevisiae. Sin3 protein with a mass of about 175 kDa is a member of the RPD3 protein complex with an assessed mass of greater than 2 million Da. It was previously shownthat RPD3 gene mutations influence recombination and repair processes in S.

[RAD18 gene product of yeast Saccharomyces cerevisiae controls mutagenesis induced by hydrogen peroxide].

Within eukaryotes, tolerance to DNA damage is determined primarily by the repair pathway controlled by the members of the RAD6 epistasis group. Genetic studies on a yeast Saccharomyces cerevisiae model showed that the initial stage of postreplication repair (PRR), i.e.

[Gene RAD31 is identical to gene MEC1 of yeast Saccharomyces cerevisiae].

The earlier identified gene RAD31 was mapped on the right arm of chromosome II in the region of gene MEC1 localization. Epistatic analysis demonstrated that the rad31 mutation is an allele of the MEC1 gene, which allows further designation of the rad31 mutation as mec1-212. Mutation mec1-212, similar to deletion alleles of this gene, causes sensitivity to hydroxyurea, disturbs the check-point function, and suppresses UV-induced mutagenesis.

[The effect of point amino acid substitutions in an internal alpha-helix on thermostability of Aspergillus awamori X100 glucoamylase].

Conformational flexibility of alpha-helices in glucoamylase of the fungus Aspergillus awamori was studied by molecular dynamics methods. Several amino acid substitutions (G127A, P128A, I136L, G137A, and G139A) optimizing intrinsic interactions in one of the alpha-helices (D) within the hydrophobic core of this protein were constructed and studied. It was found that these point mutations had different effects on the glucoamylase thermal inactivation constant.

[The Rdh54 protein role in regulation of DNA repair in yeast Saccharomyces cerevisiae].

In this work, we present the evidences of the involvement of Rdh54 in coordination of DNA repair by several pathways. Previously, we isolated rdh54-29 point mutation demonstrating unique properties different from the full deletion of RDH54 gene. Epistatic interaction between rdh54-29 and apn1delta mutations discloses the function of Rdh54p in the process of base excision repair.

The REC41 gene of Saccharomyces cerevisiae: isolation and genetic analysis.

Recombination-deficient strains have been proven useful for the understanding of the genetic control of homologous recombination. As the genetic screens used to isolate recombination-deficient (rec(-)) yeast mutants have not been saturated, we sought to develop a simple colony color assay to identify mutants with low or elevated rates of recombination. Using this system we isolated a collection of rec(-) mutants.

[RAD29 and RAD31--new genes from Saccharomyces cerevisiae yeasts, participating in control of DNA repair. II. Clarification of possible functions of these genes].

Possible functions of previously described genes RAD29 and RAD31 involved in DNA repair were determined by analyzing the interaction between these genes and mutations in the genes of the three basic epistatic groups: RAD3 (nucleotide excision repair), RAD6 (error-prone mutagenic repair system), RAD52 (recombination repair pathway), and also the apn1 mutation that blocks the synthesis of major AP endonuclease (base excision repair). The results obtained in these studies and the estimation of the capability for excision repair of lesions induced by 8-metoxipsoralen and subsequent exposure to long-wavelength UV light in mutants for these genes led to the assumption that the RAD29 and RAD31 genes are involved in yeast DNA repair control.

[RAD29 and RAD31--new genes from Saccharomyces cerevisiae yeasts, participating in control of DNA repair. Isolation and genetic study of mutants].

Base excision repair (BER) and nucleotide excision repair (NER) are two main cellular responses to DNA damage induced by various physical and chemical factors. After exposure of the strain that carries the NER-blocking rad2 mutation to UV light, several mutants hypersensitive to the UV light lethal action and simultaneously sensitive to methylmethanesulphonate (MMS) were isolated. Two of these mutants (Uvs64 and Uvs212) were examined in detail.

UVS112--A gene involved in excision repair of yeast.

In this study we show that the previously described uvs112 (uvs12) mutation blocks one of the steps of the excision repair pathway. The properties of this mutation permit the assignment of the UVS112 gene to the RAD3 epistasis group. It was established that the uvs112 mutation caused a 2.

[The xrs2 gene controls recombination repair in yeast].

The XRS2 mutants of Saccharomyces cerevisiae are sensitive to ionizing and UV irradiation, have altered rates of spontaneous and induced mitotic recombination and are defective in meiosis. Haploid xrs2 cells bearing a mutation in RAD51 or RAD52 genes are more sensitive to gamma-rays than respective single mutants. On the other hand, double mutants xrs2-6 and rad50-1 (cdc40-1, radH) have the same radiosensitivity as the single mutants.

[Rec41--a new gene, participating in the control of recombination in Saccharomyces cerevisiae yeast].

We isolated a collection of rec- mutants. The mutant rec41 from this collection was studied in detail. The mutant demonstrated a reduced level of interplasmid recombination, did not grow at the elevated temperature (36 degrees C) and was sensitive to gamma-rays but not to ultraviolet irradiation.

[A new system of selecting yeast mutants with disrupted genetic recombination processes].

A new convenient system for isolation of the yeast mutants deficient in the genetical recombination is proposed. The chimeric plasmids constructed to carry the noncomplimenting mutant copy of the yeast ADE2 gene and different selectable yeast markers (LEU2 or TRP1 genes) are the basis for the system. Interplasmid intragenic recombination of ADE2 gene alleles in yeast cells transformed by two chimeric plasmids results in appearance of the secondary white prototrophic clones covering the primary red colony.

[Genetic control of plasmid recombination in the cotransformation of Saccharomyces cerevisiae: the role of RAD52 and FLP genes].

In our earlier works we observed high frequency of recombination between two chimeric plasmids of different types, when they were introduced into yeast cells via cotransformation. Incapability of one of these plasmids to replicate autonomously in yeast cell is the necessary condition for such recombination. The high efficiency of this process point to the differences between interplasmid recombination and other types of yeast recombination.

[Repair of plasmid DNA treated with 8-methoxypsoralen and long-wave UV light (lambda=365 nm) in wild type and mutant rad2 cells of Saccharomyces cerevisiae].

The method of repeated irradiation has been used to study excision of 8-MOP monoadducts from plasmid and chromosomal DNA in cells of wild type and rad2 mutant of Saccharomyces cerevisiae. The measurement of kinetics of monoadduct removal from chromosomal DNA in intact and competent yeast cells showed that monoadducts were excised in both types of cells with normal repair, but this process was blocked in intact and competent cells of the rad2 mutant. The survival of pYF91 plasmid treated in vitro with 8-MOP plus near UV-light has been studied in the cells of the wild type and in incision-defective rad2 mutant by the measurement of cell transformation frequency.

[Recombinant plasmids carrying multiple markers: isolation during yeast co-transformation].

Cotransformants of yeast cells by two partially homologous plasmids, one of which is incapable of autonomous replication, has been used to construct multiply marked recombinant plasmids. Only simultaneous elimination of three yeast markers was registered when episomal plasmid, carrying Ade2 gene, and integrative plasmid, carrying yeast genes LEU2 and URA3, were cotransformed. Transformants, in which yeast genes LEU2, URA3 and HIS3 are linked, have been isolated by analogous technique.

[Insertion of transposon Tn9 into the spinal (Escherichia coli-Saccharomyces cerevisiae) plasmids and the expression of the prokaryotic gene of chloramphenicol resistance in yeast cells].

Transposon Tn9 carrying camr gene which controls resistance to chloramphenicol has been introduced in vivo (in cells of Escherichia coli) into two chimeric shuttle plasmids pYF91 and YEp13. These plasmids consist of the different parts of the E. coli plasmid pBR322, the yeast 2mkm DNA plasmid and the yeast LEU2 structural gene.

Genetic analysis of an osmotic sensitive Saccharomyces cerevisiae mutant.

The genetic analysis of VY1160 sorbitol dependent, osmotic sensitive yeast mutant led to the identification of three different nuclear recessive mutations. Two of them, designated sorb- and ts1 are closely linked to one another. The mutation sorb- determines the lysis, while the mutation ts1 increases the ability for lysis of the sorbitol dependent cells.