scholarly journals Analysis of mitotic and meiotic defects in Saccharomyces cerevisiae SRS2 DNA helicase mutants.

Genetics ◽  
1992 ◽  
Vol 132 (1) ◽  
pp. 23-37 ◽  
Author(s):  
F Palladino ◽  
H L Klein
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Helicase ◽  
Missense Mutations ◽  
Spore Viability ◽  
Mutational Change ◽  
Uv Sensitivity ◽  
Helicase Gene ◽  
Definition Of ◽  
Gene Variability ◽  
New Alleles

Abstract The hyper-gene conversion srs2-101 mutation of the SRS2 DNA helicase gene of Saccharomyces cerevisiae has been reported to suppress the UV sensitivity of rad18 mutants. New alleles of SRS2 were recovered using this suppressor phenotype. The alleles have been characterized with respect to suppression of rad18 UV sensitivity, hyperrecombination, reduction of meiotic viability, and definition of the mutational change within the SRS2 gene. Variability in the degree of rad18 suppression and hyperrecombination were found. The alleles that showed the severest effects were found to be missense mutations within the consensus domains of the DNA helicase family of proteins. The effect of mutations in domains I (ATP-binding) and V (proposed DNA binding) are reported. Some alleles of SRS2 reduce spore viability to 50% of wild-type levels. This phenotype is not bypassed by spo13 mutation. Although the srs2 homozygous diploids strains undergo normal commitment to meiotic recombination, this event is delayed by several hours in the mutant strains and the strains appear to stall in the progression from meiosis I to meiosis II.

scholarly journals A Saccharomyces cerevisiae RAD52 allele expressing a C-terminal truncation protein: activities and intragenic complementation of missense mutations.

Genetics ◽  
1993 ◽  
Vol 133 (1) ◽  
pp. 39-49 ◽  
Author(s):  
K L Boundy-Mills ◽  
D M Livingston
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Repair ◽  
Deletion Mutants ◽  
Crossing Over ◽  
Missense Mutations ◽  
Wild Type ◽  
Spore Viability ◽  
Deletion Allele ◽  
Low Level ◽  
Intragenic Complementation

Abstract A nonsense allele of the yeast RAD52 gene, rad52-327, which expresses the N-terminal 65% of the protein was compared to two missense alleles, rad52-1 and rad52-2, and to a deletion allele. While the rad52-1 and the deletion mutants have severe defects in DNA repair, recombination and sporulation, the rad52-327 and rad52-2 mutants retain either partial or complete capabilities in repair and recombination. These two mutants behave similarly in most tests of repair and recombination during mitotic growth. One difference between these two alleles is that a homozygous rad52-2 diploid fails to sporulate, whereas the homozygous rad52-327 diploid sporulates weakly. The low level of sporulation by the rad52-327 diploid is accompanied by a low percentage of spore viability. Among these viable spores the frequency of crossing over for markers along chromosome VII is the same as that found in wild-type spores. rad52-327 complements rad52-2 for repair and sporulation. Weaker intragenic complementation occurs between rad52-327 and rad52-1.

scholarly journals The SRS2 suppressor of rad6 mutations of Saccharomyces cerevisiae acts by channeling DNA lesions into the RAD52 DNA repair pathway.

Genetics ◽  
1990 ◽  
Vol 124 (4) ◽  
pp. 817-831 ◽  
Author(s):  
R H Schiestl ◽  
S Prakash ◽  
L Prakash
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Repair ◽  
Gamma Ray ◽  
Dna Lesions ◽  
Recombinational Repair ◽  
Repair Pathway ◽  
Uv Mutagenesis ◽  
Uv Sensitivity ◽  
Suppressor Mutations ◽  
Induced Mutagenesis

Abstract rad6 mutants of Saccharomyces cerevisiae are defective in the repair of damaged DNA, DNA damage induced mutagenesis, and sporulation. In order to identify genes that can substitute for RAD6 function, we have isolated genomic suppressors of the UV sensitivity of rad6 deletion (rad6 delta) mutations and show that they also suppress the gamma-ray sensitivity but not the UV mutagenesis or sporulation defects of rad6. The suppressors show semidominance for suppression of UV sensitivity and dominance for suppression of gamma-ray sensitivity. The six suppressor mutations we isolated are all alleles of the same locus and are also allelic to a previously described suppressor of the rad6-1 nonsense mutation, SRS2. We show that suppression of rad6 delta is dependent on the RAD52 recombinational repair pathway since suppression is not observed in the rad6 delta SRS2 strain containing an additional mutation in either the RAD51, RAD52, RAD54, RAD55 or RAD57 genes. Possible mechanisms by which SRS2 may channel unrepaired DNA lesions into the RAD52 DNA repair pathway are discussed.

scholarly journals Requirement for Three Novel Protein Complexes in the Absence of the Sgs1 DNA Helicase in Saccharomyces cerevisiae

Genetics ◽  
2001 ◽  
Vol 157 (1) ◽  
pp. 103-118 ◽  
Author(s):  
Janet R Mullen ◽  
Vivek Kaliraman ◽  
Samer S Ibrahim ◽  
Steven J Brill
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Genome Stability ◽  
Protein Complexes ◽  
Ring Finger ◽  
Dna Helicase ◽  
Open Reading Frames ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Dna Helicases ◽  
Cell Extracts

Abstract The Saccharomyces cerevisiae Sgs1 protein is a member of the RecQ family of DNA helicases and is required for genome stability, but not cell viability. To identify proteins that function in the absence of Sgs1, a synthetic-lethal screen was performed. We obtained mutations in six complementation groups that we refer to as SLX genes. Most of the SLX genes encode uncharacterized open reading frames that are conserved in other species. None of these genes is required for viability and all SLX null mutations are synthetically lethal with mutations in TOP3, encoding the SGS1-interacting DNA topoisomerase. Analysis of the null mutants identified a pair of genes in each of three phenotypic classes. Mutations in MMS4 (SLX2) and SLX3 generate identical phenotypes, including weak UV and strong MMS hypersensitivity, complete loss of sporulation, and synthetic growth defects with mutations in TOP1. Mms4 and Slx3 proteins coimmunoprecipitate from cell extracts, suggesting that they function in a complex. Mutations in SLX5 and SLX8 generate hydroxyurea sensitivity, reduced sporulation efficiency, and a slow-growth phenotype characterized by heterogeneous colony morphology. The Slx5 and Slx8 proteins contain RING finger domains and coimmunoprecipitate from cell extracts. The SLX1 and SLX4 genes are required for viability in the presence of an sgs1 temperature-sensitive allele at the restrictive temperature and Slx1 and Slx4 proteins are similarly associated in cell extracts. We propose that the MMS4/SLX3, SLX5/8, and SLX1/4 gene pairs encode heterodimeric complexes and speculate that these complexes are required to resolve recombination intermediates that arise in response to DNA damage, during meiosis, and in the absence of SGS1/TOP3.

scholarly journals A Role for MMS4 in the Processing of Recombination Intermediates During Meiosis in Saccharomyces cerevisiae

Genetics ◽  
2001 ◽  
Vol 159 (4) ◽  
pp. 1511-1525 ◽  
Author(s):  
Teresa de los Santos ◽  
Josef Loidl ◽  
Brittany Larkin ◽  
Nancy M Hollingsworth
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Meiotic Recombination ◽  
Biochemical Data ◽  
Dna Metabolism ◽  
Spore Viability ◽  
Vegetative Cells ◽  
Recombination Checkpoint

Abstract The MMS4 gene of Saccharomyces cerevisiae was originally identified due to its sensitivity to MMS in vegetative cells. Subsequent studies have confirmed a role for MMS4 in DNA metabolism of vegetative cells. In addition, mms4 diploids were observed to sporulate poorly. This work demonstrates that the mms4 sporulation defect is due to triggering of the meiotic recombination checkpoint. Genetic, physical, and cytological analyses suggest that MMS4 functions after the single end invasion step of meiotic recombination. In spo13 diploids, red1, but not mek1, is epistatic to mms4 for sporulation and spore viability, suggesting that MMS4 may be required only when homologs are capable of undergoing synapsis. MMS4 and MUS81 are in the same epistasis group for spore viability, consistent with biochemical data that show that the two proteins function in a complex. In contrast, MMS4 functions independently of MSH5 in the production of viable spores. We propose that MMS4 is required for the processing of specific recombination intermediates during meiosis.

Isolation, DNA sequence, and regulation of a Saccharomyces cerevisiae gene that encodes DNA strand transfer protein alpha

1991 ◽  
Vol 11 (5) ◽  
pp. 2576-2582
Author(s):  
A B Clark ◽  
C C Dykstra ◽  
A Sugino
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Specific Activity ◽  
Intragenic Recombination ◽  
Strand Transfer ◽  
Homologous Pairing ◽  
Spore Viability ◽  
Transfer Protein ◽  
Acid Protein ◽  
Dna Strand ◽  
Amino Acid Protein

DNA strand transfer protein alpha (STP alpha) from meiotic Saccharomyces cerevisiae cells promotes homologous pairing of DNA without any nucleotide cofactor in the presence of yeast single-stranded DNA binding protein. This gene (DNA strand transferase 1, DST1) encodes a 309-amino-acid protein with a predicted molecular mass of 34,800 Da. The STP alpha protein level is constant in both mitotic and meiotic cells, but during meiosis the polypeptide is activated by an unknown mechanism, resulting in a large increase in its specific activity. A dst1::URA3/dst1::URA3 mutant grows normally in mitotic media; however, meiotic cells exhibit a greatly reduced induction of both DNA strand transfer activity and intragenic recombination between his1 heteroalleles. Spore viability is normal. These results suggest that DST1 is required for much of the observed induction of homologous recombination in S. cerevisiae during meiosis but not for normal sporulation.

Reconstitution of the vitamin D-responsive osteocalcin transcription unit in Saccharomyces cerevisiae

1989 ◽  
Vol 9 (8) ◽  
pp. 3517-3523
Author(s):  
D P McDonnell ◽  
J W Pike ◽  
D J Drutz ◽  
T R Butt ◽  
B W O'Malley
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Vitamin D ◽  
Transcription Factors ◽  
Promoter Activity ◽  
Transcription Unit ◽  
Proximal Promoter ◽  
Regulatory Sequences ◽  
Cis Acting ◽  
Osteocalcin Gene ◽  
Definition Of

The human osteocalcin gene is regulated in mammalian osteoblasts by 1,25(OH)2D3-dependent and -independent mechanisms. The sequences responsible for this activity have been mapped to within the -1339 region of the gene. We show here that this enhancer region functions analogously in Saccharomyces cerevisiae cells engineered to produce active 1,25(OH)2D3 receptor. When fused to the proximal promoter elements of the yeast iso-1-cytochrome c gene, the enhancer demonstrated substantial promoter activity. This activity was elevated further by 1,25(OH)2D3 when the reporter constructs were assayed in cells containing the 1,25(OH)2D3 receptor. This system affords a model for 1,25(OH)2D3 action and represents a simple assay system that will enable definition of the important cis-acting regulatory sequences within the osteocalcin gene and identification of their cognate transcription factors.

scholarly journals Saccharomyces cerevisiae Rrm3p DNA Helicase Promotes Genome Integrity by Preventing Replication Fork Stalling: Viability of rrm3 Cells Requires the Intra-S-Phase Checkpoint and Fork Restart Activities

2004 ◽  
Vol 24 (8) ◽  
pp. 3198-3212 ◽  
Author(s):  
Jorge Z. Torres ◽  
Sandra L. Schnakenberg ◽  
Virginia A. Zakian
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Dna Damage ◽  
Replication Fork ◽  
Opportunity To Learn ◽  
Normal Growth ◽  
Dna Helicase ◽  
S Phase ◽  
Exogenous Dna ◽  
Fork Stalling ◽  
S Phase Checkpoint

ABSTRACT Rrm3p is a 5′-to-3′ DNA helicase that helps replication forks traverse protein-DNA complexes. Its absence leads to increased fork stalling and breakage at over 1,000 specific sites located throughout the Saccharomyces cerevisiae genome. To understand the mechanisms that respond to and repair rrm3-dependent lesions, we carried out a candidate gene deletion analysis to identify genes whose mutation conferred slow growth or lethality on rrm3 cells. Based on synthetic phenotypes, the intra-S-phase checkpoint, the SRS2 inhibitor of recombination, the SGS1/TOP3 replication fork restart pathway, and the MRE11/RAD50/XRS2 (MRX) complex were critical for viability of rrm3 cells. DNA damage checkpoint and homologous recombination genes were important for normal growth of rrm3 cells. However, the MUS81/MMS4 replication fork restart pathway did not affect growth of rrm3 cells. These data suggest a model in which the stalled and broken forks generated in rrm3 cells activate a checkpoint response that provides time for fork repair and restart. Stalled forks are converted by a Rad51p-mediated process to intermediates that are resolved by Sgs1p/Top3p. The rrm3 system provides a unique opportunity to learn the fate of forks whose progress is impaired by natural impediments rather than by exogenous DNA damage.

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