scholarly journals Shu Proteins Promote the Formation of Homologous Recombination Intermediates That Are Processed by Sgs1-Rmi1-Top3

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.

2012 ◽  
Vol 48 (3) ◽  
pp. 284-290 ◽  
Author(s):  
A. Yu. Chernenkov ◽  
D. V. Fedorov ◽  
L. M. Gracheva ◽  
T. A. Evstuhina ◽  
S. V. Kovaltsova ◽  
...  

2009 ◽  
Vol 20 (4) ◽  
pp. 1241-1251 ◽  
Author(s):  
Ling Xiong ◽  
Xiaole L. Chen ◽  
Hannah R. Silver ◽  
Noreen T. Ahmed ◽  
Erica S. Johnson

Many Saccharomyces cerevisiae mutants defective in the SUMO pathway accumulate elevated levels of the native 2 μm circle plasmid (2 μm). Here we show that accumulation of 2 μm in the SUMO pathway mutants siz1Δ siz2Δ, slx5Δ, and slx8Δ is associated with formation of an aberrant high-molecular-weight (HMW) form of 2 μm. Characterization of this species from siz1Δ siz2Δ showed that it contains tandem copies of the 2 μm sequence as well as single-stranded DNA. Accumulation of this species requires both the 2 μm–encoded Flp recombinase and the cellular homologous recombination repair (HRR) pathway. Importantly, reduced SUMO attachment to Flp is sufficient to induce formation of this species. Our data suggest a model in which Flp that cannot be sumoylated causes DNA damage, whose repair via HRR produces an intermediate that generates tandem copies of the 2 μm sequence. This intermediate may be a rolling circle formed via break-induced replication (BIR), because mutants defective in BIR contain reduced levels of the HMW form. This work also illustrates the importance of using cir° strains when studying mutants that affect the yeast SUMO pathway, to avoid confusing direct functions of the SUMO pathway with secondary effects of 2 μm amplification.


2009 ◽  
Vol 20 (6) ◽  
pp. 1683-1694 ◽  
Author(s):  
Hocine W. Mankouri ◽  
Hien-Ping Ngo ◽  
Ian D. Hickson

Esc2 is a member of the RENi family of SUMO-like domain proteins and is implicated in gene silencing in Saccharomyces cerevisiae. Here, we identify a dual role for Esc2 during S-phase in mediating both intra-S-phase DNA damage checkpoint signaling and preventing the accumulation of Rad51-dependent homologous recombination repair (HRR) intermediates. These roles are qualitatively similar to those of Sgs1, the yeast ortholog of the human Bloom's syndrome protein, BLM. However, whereas mutation of either ESC2 or SGS1 leads to the accumulation of unprocessed HRR intermediates in the presence of MMS, the accumulation of these structures in esc2 (but not sgs1) mutants is entirely dependent on Mph1, a protein that shows structural similarity to the Fanconi anemia group M protein (FANCM). In the absence of both Esc2 and Sgs1, the intra-S-phase DNA damage checkpoint response is compromised after exposure to MMS, and sgs1esc2 cells attempt to undergo mitosis with unprocessed HRR intermediates. We propose a model whereby Esc2 acts in an Mph1-dependent process, separately from Sgs1, to influence the repair/tolerance of MMS-induced lesions during S-phase.


AIMS Genetics ◽  
2018 ◽  
Vol 5 (2) ◽  
pp. 161-176
Author(s):  
Huong Thi Thu Phung ◽  
◽  
Hoa Luong Hieu Nguyen ◽  
Dung Hoang Nguyen

2019 ◽  
Vol 14 (9) ◽  
pp. 122
Author(s):  
Phung Thi Thu Huong ◽  
Tran Hong Diem ◽  
Nguyen Luong Hieu Hoa ◽  
Vo Thanh Sang ◽  
Le Van Minh ◽  
...  

Mus81-Mms4 is a well conserved DNA structure–specific endonuclease and efficiently cleaves different DNA structures that could arise during the repair of stalled/blocked replication forks and homologous recombination repair. Rad52 is an ezyme that stimulates main steps of  DNA sequence-homology searching. In this study, we proved that Rad52 and Mus81-Mms4 possess a species-specific functional interaction, indicating that Rad52 and Mus81-Mms4 collaborate in processing of homologous recombination intermediates.


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