Pie1, a protein interacting with Mec1, controls cell growth and checkpoint responses in Saccharomyces cerevisiae.
In eukaryotes, the ATM and ATR family proteins play a critical role in the DNA damage and replication checkpoint controls. These proteins are characterized by a kinase domain related to the phosphatidylinositol 3-kinase, but they have the ability to phosphorylate proteins. In budding yeast, the ATR family protein Mec1/Esr1 is essential for checkpoint responses and cell growth. We have isolated the PIE1 gene in a two-hybrid screen for proteins that interact with Mec1, and we show that Pie1 interacts physically with Mec1 in vivo. Like MEC1, PIE1 is essential for cell growth, and deletion of the PIE1 gene causes defects in the DNA damage and replication block checkpoints similar to those observed in mec1Delta mutants. Rad53 hyperphosphorylation following DNA damage and replication block is also decreased in pie1Delta cells, as in mec1Delta cells. Pie1 has a limited homology to fission yeast Rad26, which forms a complex with the ATR family protein Rad3. Mutation of the region in Pie1 homologous to Rad26 results in a phenotype similar to that of the pie1Delta mutation. Mec1 protein kinase activity appears to be essential for checkpoint responses and cell growth. However, Mec1 kinase activity is unaffected by the pie1Delta mutation, suggesting that Pie1 regulates some essential function other than Mec1 kinase activity. Thus, Pie1 is structurally and functionally related to Rad26 and interacts with Mec1 to control checkpoints and cell proliferation.
Wakayama
T
T
Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-0814, Japan.
Kondo
T
T
Ando
S
S
Matsumoto
K
K
Sugimoto
K
K
D000595:Amino Acid Sequence; D001483:Base Sequence; D002455:Cell Division; D017124:Conserved Sequence; D004249:DNA Damage; D017931:DNA Primers / Q000235:genetics; D004260:DNA Repair; D004261:DNA Replication; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D005800:Genes, Fungal; D047908:Intracellular Signaling Peptides and Proteins; D008969:Molecular Sequence Data; D009154:Mutation; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid
D017931:DNA Primers; D005656:Fungal Proteins; D047908:Intracellular Signaling Peptides and Proteins; D029701:Saccharomyces cerevisiae Proteins; D011494:Protein Kinases; C088937:MEC1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases