scholarly journals Epistasis analysis between homologous recombination genes in Saccharomyces cerevisiae identifies multiple repair pathways for Sgs1, Mus81-Mms4 and RNase H2

Author(s):  
Miki Ii ◽  
Tatsuya Ii ◽  
Larisa I. Mironova ◽  
Steven J. Brill
2020 ◽  
Author(s):  
Daniele Novarina ◽  
Ridhdhi Desai ◽  
Jessica A. Vaisica ◽  
Jiongwen Ou ◽  
Mohammed Bellaoui ◽  
...  

ABSTRACTHomologous recombination is an important mechanism for genome integrity maintenance, and several homologous recombination genes are mutated in various cancers and cancer-prone syndromes. However, since in some cases homologous recombination can lead to mutagenic outcomes, this pathway must be tightly regulated, and mitotic hyper-recombination is a hallmark of genomic instability. We performed two screens in Saccharomyces cerevisiae for genes that, when deleted, cause hyper-recombination between direct repeats. One was performed with the classical patch and replica-plating method. The other was performed with a high-throughput replica-pinning technique that was designed to detect low-frequency events. This approach allowed us to validate the high-throughput replica-pinning methodology independently of the replicative aging context in which it was developed. Furthermore, by combining the two approaches, we were able to identify and validate 35 genes whose deletion causes elevated spontaneous direct-repeat recombination. Among these are mismatch repair genes, the Sgs1-Top3-Rmi1 complex, the RNase H2 complex, genes involved in the oxidative stress response, and a number of other DNA replication, repair and recombination genes. Since several of our hits are evolutionary conserved, and repeated elements constitute a significant fraction of mammalian genomes, our work might be relevant for understanding genome integrity maintenance in humans.


2020 ◽  
Vol 10 (6) ◽  
pp. 1853-1867
Author(s):  
Daniele Novarina ◽  
Ridhdhi Desai ◽  
Jessica A. Vaisica ◽  
Jiongwen Ou ◽  
Mohammed Bellaoui ◽  
...  

Homologous recombination is an important mechanism for genome integrity maintenance, and several homologous recombination genes are mutated in various cancers and cancer-prone syndromes. However, since in some cases homologous recombination can lead to mutagenic outcomes, this pathway must be tightly regulated, and mitotic hyper-recombination is a hallmark of genomic instability. We performed two screens in Saccharomyces cerevisiae for genes that, when deleted, cause hyper-recombination between direct repeats. One was performed with the classical patch and replica-plating method. The other was performed with a high-throughput replica-pinning technique that was designed to detect low-frequency events. This approach allowed us to validate the high-throughput replica-pinning methodology independently of the replicative aging context in which it was developed. Furthermore, by combining the two approaches, we were able to identify and validate 35 genes whose deletion causes elevated spontaneous direct-repeat recombination. Among these are mismatch repair genes, the Sgs1-Top3-Rmi1 complex, the RNase H2 complex, genes involved in the oxidative stress response, and a number of other DNA replication, repair and recombination genes. Since several of our hits are evolutionarily conserved, and repeated elements constitute a significant fraction of mammalian genomes, our work might be relevant for understanding genome integrity maintenance in humans.


2004 ◽  
Vol 24 (12) ◽  
pp. 5130-5143 ◽  
Author(s):  
Christine Soustelle ◽  
Laurence Vernis ◽  
Karine Fréon ◽  
Anne Reynaud-Angelin ◽  
Roland Chanet ◽  
...  

ABSTRACT The Saccharomyces cerevisiae Srs2 protein is involved in DNA repair and recombination. In order to gain better insight into the roles of Srs2, we performed a screen to identify mutations that are synthetically lethal with an srs2 deletion. One of them is a mutated allele of the ULP1 gene that encodes a protease specifically cleaving Smt3-protein conjugates. This allele, ulp1-I615N, is responsible for an accumulation of Smt3-conjugated proteins. The mutant is unable to grow at 37°C. At permissive temperatures, it still shows severe growth defects together with a strong hyperrecombination phenotype and is impaired in meiosis. Genetic interactions between ulp1 and mutations that affect different repair pathways indicated that the RAD51-dependent homologous recombination mechanism, but not excision resynthesis, translesion synthesis, or nonhomologous end-joining processes, is required for the viability of the mutant. Thus, both Srs2, believed to negatively control homologous recombination, and the process of recombination per se are essential for the viability of the ulp1 mutant. Upon replication, mutant cells accumulate single-stranded DNA interruptions. These structures are believed to generate different recombination intermediates. Some of them are fixed by recombination, and others require Srs2 to be reversed and fixed by an alternate pathway.


Mutagenesis ◽  
2013 ◽  
Vol 28 (2) ◽  
pp. 187-195 ◽  
Author(s):  
L. Spugnesi ◽  
C. Balia ◽  
A. Collavoli ◽  
E. Falaschi ◽  
V. Quercioli ◽  
...  

DNA Repair ◽  
2007 ◽  
Vol 6 (10) ◽  
pp. 1496-1506 ◽  
Author(s):  
YoungHo Kwon ◽  
Peter Chi ◽  
Dong Hyun Roh ◽  
Hannah Klein ◽  
Patrick Sung

2007 ◽  
Vol 18 (10) ◽  
pp. 4062-4073 ◽  
Author(s):  
Hocine W. Mankouri ◽  
Hien-Ping Ngo ◽  
Ian D. Hickson

CSM2, PSY3, SHU1, and SHU2 (collectively referred to as the SHU genes) were identified in Saccharomyces cerevisiae as four genes in the same epistasis group that suppress various sgs1 and top3 mutant phenotypes when mutated. Although the SHU genes have been implicated in homologous recombination repair (HRR), their precise role(s) within this pathway remains poorly understood. Here, we have identified a specific role for the Shu proteins in a Rad51/Rad54-dependent HRR pathway(s) to repair MMS-induced lesions during S-phase. We show that, although mutation of RAD51 or RAD54 prevented the formation of MMS-induced HRR intermediates (X-molecules) arising during replication in sgs1 cells, mutation of SHU genes attenuated the level of these structures. Similar findings were also observed in shu1 cells in which Rmi1 or Top3 function was impaired. We propose a model in which the Shu proteins act in HRR to promote the formation of HRR intermediates that are processed by the Sgs1-Rmi1-Top3 complex.


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