Reconstitution of a MEC1-independent checkpoint in yeast by expression of a novel human fork head cDNA.
A novel human cDNA, CHES1 (checkpoint suppressor 1), has been isolated by suppression of the mec1-1 checkpoint mutation in Saccharomyces cerevisiae. CHES1 suppresses a number of DNA damage-activated checkpoint mutations in S. cerevisiae, including mec1, rad9, rad24, dun1, and rad53. CHES1 suppression of sensitivity to DNA damage is specific for checkpoint-defective strains, in contrast to DNA repair-defective strains. Presence of CHES1 but not a control vector resulted in G2 delay after UV irradiation in checkpoint-defective strains, with kinetics, nuclear morphology, and cycloheximide resistance similar to those of a wild-type strain. CHES1 can also suppress the lethality, UV sensitivity, and G2 checkpoint defect of a mec1 null mutation. In contrast to this activity, CHES1 had no measurable effect on the replication checkpoint as assayed by hydroxyurea sensitivity of a mec1 strain. Sequence analysis demonstrates that CHES1 is a novel member of the fork head/Winged Helix family of transcription factors. Suppression of the checkpoint-defective phenotype requires a 200-amino-acid domain in the carboxy terminus of the protein which is distinct from the DNA binding site. Analysis of CHES1 activity is most consistent with activation of an alternative MEC1-independent checkpoint pathway in budding yeast.
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Texas Children's Cancer Center, Department of Pediatrics, Baylor College of Medicine, Houston 77030, USA.
Keller
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Groudine
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Plon
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D000595:Amino Acid Sequence; D001483:Base Sequence; D002453:Cell Cycle; D018797:Cell Cycle Proteins; D004249:DNA Damage / Q000235:genetics; D004260:DNA Repair; D018076:DNA, Complementary / Q000737:chemistry / Q000302:isolation & purification; D051858:Forkhead Transcription Factors; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D016195:G2 Phase; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D007700:Kinetics; D008969:Molecular Sequence Data; D016296:Mutagenesis / Q000187:drug effects; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D016366:Open Reading Frames; D011401:Promoter Regions, Genetic; D017346:Protein Serine-Threonine Kinases; D011836:Radiation Tolerance / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014466:Ultraviolet Rays
D018797:Cell Cycle Proteins; D018076:DNA, Complementary; C106158:FOXN3 protein, human; D051858:Forkhead Transcription Factors; D005656:Fungal Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009687:Nuclear Proteins; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; C088937:MEC1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases