The ATM homologue MEC1 is required for phosphorylation of replication protein A in yeast

• Published in: Proceedings of the National Academy of Sciences - PNAS 1996-12, Vol.93 (26), p.15075-15080
• Main Authors: Brush, G.S. (The Johns Hopkins University School of Medicine, Baltimore, MD.), Morrow, D.M, Hieter, P, Kelly, T.J
• Format: Article
• Language: English
• Subjects: ADN; AMIDAS; AMIDE; Ataxia telangiectasia; Ataxia Telangiectasia - genetics; Ataxia Telangiectasia Mutated Proteins; Biological Sciences; Cell culture techniques; Cell cycle; Cell Cycle - radiation effects; Cell Cycle Proteins; DIVISION CELLULAIRE; DIVISION CELULAR; DNA; DNA damage; DNA Repair; DNA Replication; DNA-Binding Proteins - metabolism; FOSFORILACION; Fungal Proteins - genetics; Fungal Proteins - metabolism; GENE; GENES; Genes, Fungal; Genotype; Humans; Intracellular Signaling Peptides and Proteins; Ionizing radiation; Models, Biological; PHOSPHORYLATION; Point Mutation; Protein-Serine-Threonine Kinases; PROTEINA QUINASA; PROTEINAS AGLUTINANTES; PROTEINE DE LIAISON; PROTEINE KINASE; Proteins - genetics; RADIACION IONIZANTE; RADIACION ULTRAVIOLETA; Radiation damage; RADIATION IONISANTE; Radiation, Ionizing; RAYONNEMENT ULTRAVIOLET; Replication Protein A; SACCHAROMYCES CEREVISIAE; Saccharomyces cerevisiae - cytology; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae - radiation effects; Saccharomyces cerevisiae Proteins; Tumor Suppressor Proteins; Ultraviolet Rays; Yeasts
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.93.26.15075

Replication protein A (RPA) is a highly conserved single-stranded DNA-binding protein, required for cellular DNA replication, repair, and recombination. In human cells, RPA is phosphorylated during the S and G2 phases of the cell cycle and also in response to ionizing or ultraviolet radiation. Saccharomyces cerevisiae exhibits a similar pattern of cell cycle-regulated RPA phosphorylation, and our studies indicate that the radiation-induced reactions occur in yeast as well. We have examined yeast RPA phosphorylation during the normal cell cycle and in response to environmental insult, and have demonstrated that the checkpoint gene MEC1 is required for the reaction under all conditions tested. Through examination of several checkpoint mutants, we have placed RPA phosphorylation in a novel pathway of the DNA damage response. MEC1 is similar in sequence to human ATM, the gene mutated in patients with ataxia-telangiectasia (A-T). A-T cells are deficient in multiple checkpoint pathways and are hypersensitive to killing by ionizing radiation. Because A-T cells exhibit a delay in ionizing radiation-induced RPA phosphorylation, our results indicate a functional similarity between MEC1 and ATM, and suggest that RPA phosphorylation is involved in a conserved eukaryotic DNA damage-response pathway defective in A-T