title: Mec1-dependent phosphorylation of Mms21 modulates its SUMO ligase activity.
abstract: The SUMO ligase Mms21, which is a subunit of the Smc5/6 complex, is required for DNA repair. Here we present results showing that Mms21 was phosophorylated during S-phase in a manner dependent on the DNA damage kinase Mec1. Phosphorylation of Mms21 occurred in unchallenged cells, but was more abundant in the presence of DNA damaging agents. Mass spectrometry identified five phosphorylated serines organized in two regions of Mms21, and two C-terminal serines, S260 and S261, formed part of a Mec1/Tel1 consensus motif. Nonphosphorylatable substitutions of the C-terminal serines, inactivation of Mec1 or removal of the Mms21 C-terminus all abolished Mms21 phosphorylation. Additionally, strains carrying Mms21 phosphoablative alleles displayed reduced SUMO ligase activity, sensitivity to MMS and an increased rate of chromosome loss in the presence of MMS. We propose that one function of S260 S261 phosphorylation is to positively regulate the SUMO ligase activity of Mms21 and thereby promote genomic stability.
authors: Department of Cell and Molecular Biology, Karolinska Institute, 171 77 Stockholm, Sweden. Electronic address: kristian.carlborg@ki.se.
authors: Kristian K
authors: KK
authors: Carlborg
authors: Department of Cell and Molecular Biology, Karolinska Institute, 171 77 Stockholm, Sweden. Electronic address: takaharu.kanno@ki.se.
authors: Takaharu
authors: T
authors: Kanno
authors: Department of Cell and Molecular Biology, Karolinska Institute, 171 77 Stockholm, Sweden. Electronic address: sidney.carter-dewey@ki.se.
authors: Sidney D
authors: SD
authors: Carter
authors: Department of Cell and Molecular Biology, Karolinska Institute, 171 77 Stockholm, Sweden. Electronic address: camilla.sjogren@ki.se.
authors: Camilla
authors: C
authors: Sjögren
mesh_terms: D004260:DNA Repair; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D016196:S Phase; D025842:SUMO-1 Protein / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; C500948:Mms21 protein, S cerevisiae; D025842:SUMO-1 Protein; D029701:Saccharomyces cerevisiae Proteins; C088937:MEC1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases
keywords: Mec1; Mms21; Phosphorylation; SUMOylation; Smc5/6