Sae2 and Rif2 regulate MRX endonuclease activity at DNA double-strand breaks in opposite manners.
The Mre11-Rad50-Xrs2 (MRX) complex detects and processes DNA double-strand breaks (DSBs). Its DNA binding and processing activities are regulated by transitions between an ATP-bound state and a post-hydrolysis cutting state that is nucleolytically active. Mre11 endonuclease activity is stimulated by Sae2, whose lack increases MRX persistence at DSBs and checkpoint ... activation. Here we show that the Rif2 protein inhibits Mre11 endonuclease activity and is responsible for the increased MRX retention at DSBs in sae2? cells. We identify a Rad50 residue that is important for Rad50-Rif2 interaction and Rif2 inhibition of Mre11 nuclease. This residue is located near a Rad50 surface that binds Sae2 and is important in stabilizing the Mre11-Rad50 (MR) interaction in the cutting state. We propose that Sae2 stimulates Mre11 endonuclease activity by stabilizing a post-hydrolysis MR conformation that is competent for DNA cleavage, whereas Rif2 antagonizes this Sae2 function and stabilizes an endonuclease inactive MR conformation.
Mesh Terms:
Cell Cycle Checkpoints, DNA Breaks, Double-Stranded, DNA Damage, Endonucleases, Gene Deletion, Models, Biological, Multiprotein Complexes, Mutation, Protein Binding, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Telomere-Binding Proteins
Cell Cycle Checkpoints, DNA Breaks, Double-Stranded, DNA Damage, Endonucleases, Gene Deletion, Models, Biological, Multiprotein Complexes, Mutation, Protein Binding, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Telomere-Binding Proteins
Cell Rep
Date: Dec. 30, 2020
PubMed ID: 33789097
View in: Pubmed Google Scholar
Download Curated Data For This Publication
237040
Switch View:
- Interactions 3