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Fission yeast chk1 mutants show distinct responses to different types of DNA damaging treatments
Author(s) -
Francesconi Stefania,
Smeets Monique,
Gre Muriel,
Tillit Jeanne,
Blaisonneau Joël,
Baldacci Giuseppe
Publication year - 2002
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1046/j.1365-2443.2002.00552.x
Subject(s) - chek1 , g2 m dna damage checkpoint , biology , cell cycle , mutant , dna damage , schizosaccharomyces pombe , cell cycle checkpoint , ribonucleotide reductase , microbiology and biotechnology , dna repair , mutation , kinase , dna , biochemistry , cell , protein subunit , gene
Background: Chk1 kinase is activated by phosphorylation at serine‐345 by Rad3 checkpoint kinase and is required for DNA damage checkpoint in late S and G2 phase of S. pombe cell cycle. We studied the ability of two chk1 mutants, chk1‐1 and chk1‐2 , to undergo phosphorylation and to delay cell cycle progression in response to different types of DNA lesions. Results: Both the Chk1‐1 and Chk1‐2 mutant proteins are phosphorylated to various extents when DNA is damaged in early G2 phase of cell cycle by either UV irradiation or gamma irradiation. However, chk1‐2 mutant does not delay cell cycle progression in a dose dependent manner specifically upon gamma irradiations. This defect is not associated with an important loss of survival. Furthermore, both chk1 mutants survive to Camptothecin treatment despite undetectable Chk1‐1 or Chk1‐2 phosphorylated forms. We show that both mutant proteins are not phosphorylated in cds1 devoid cells treated with ribonucleotide reductase inhibitor hydroxyurea or when the replisome is affected by a thermosensitive mutation in DNA polymerase δ. This inability is associated with the loss of checkpoint function. We found that an increased level of Crb2/Rhp9 protein specifically complements the defect of the chk1‐1 mutant allowing Chk1‐1 phosphorylation upon treatment with hydroxyurea of dcds1 cells. Conclusions: Mutants chk1‐1 and chk1‐2 behave differently according to the type of lesion generated on DNA.