Cell cycle-dependent regulation of the nuclease activity of Mus81-Eme1/Mms4.
The conserved heterodimeric endonuclease Mus81-Eme1/Mms4 plays an important role in the maintenance of genomic integrity in eukaryotic cells. Here, we show that budding yeast Mus81-Mms4 is strictly regulated during the mitotic cell cycle by Cdc28 (CDK)- and Cdc5 (Polo-like kinase)-dependent phosphorylation of the non-catalytic subunit Mms4. The phosphorylation of this protein occurs only after bulk DNA synthesis and before chromosome segregation, and is absolutely necessary for the function of the Mus81-Mms4 complex. Consistently, a phosphorylation-defective mms4 mutant shows highly reduced nuclease activity and increases the sensitivity of cells lacking the RecQ-helicase Sgs1 to various agents that cause DNA damage or replicative stress. The mode of regulation of Mus81-Mms4 restricts its activity to a short period of the cell cycle, thus preventing its function during chromosome replication and the negative consequences for genome stability derived from its nucleolytic action. Yet, the controlled Mus81-Mms4 activity provides a safeguard mechanism to resolve DNA intermediates that may remain after replication and require processing before mitosis.
Centro de Biología Molecular Severo Ochoa (CSIC/UAM), Cantoblanco, 28049 Madrid, Spain.
María
M
Gallo-Fernández
Irene
I
Saugar
María Ángeles
MÁ
Ortiz-Bazán
María Victoria
MV
Vázquez
José Antonio
JA
Tercero
D017489:CDC28 Protein Kinase, S cerevisiae / Q000378:metabolism; D002453:Cell Cycle; D018797:Cell Cycle Proteins / Q000378:metabolism; D004249:DNA Damage; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004720:Endonucleases / Q000378:metabolism*; D045585:Flap Endonucleases / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D053484:RecQ Helicases / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; D017346:Protein Serine-Threonine Kinases; C081927:CDC5 protein, S cerevisiae; D017489:CDC28 Protein Kinase, S cerevisiae; D004720:Endonucleases; D045585:Flap Endonucleases; C411624:MUS81 protein, S cerevisiae; C112337:MMS4 protein, S cerevisiae; C090472:SGS1 protein, S cerevisiae; D053484:RecQ Helicases