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Analysis of Rad3 and Chk1 protein kinases defines different checkpoint responses
Author(s) -
Martinho Rui G.,
Lindsay Howard D.,
Flaggs Gail,
DeMaggio Anthony J.,
Hoekstra Merl F.,
Carr Antony M.,
Bentley Nicola J.
Publication year - 1998
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/17.24.7239
Subject(s) - carr , library science , art history , unit (ring theory) , history , biology , computer science , psychology , ecology , mathematics education
Eukaryotic cells respond to DNA damage and S phase replication blocks by arresting cell‐cycle progression through the DNA structure checkpoint pathways. In Schizosaccharomyces pombe , the Chk1 kinase is essential for mitotic arrest and is phosphorylated after DNA damage. During S phase, the Cds1 kinase is activated in response to DNA damage and DNA replication blocks. The response of both Chk1 and Cds1 requires the six ‘checkpoint Rad’ proteins (Rad1, Rad3, Rad9, Rad17, Rad26 and Hus1). We demonstrate that DNA damage‐dependent phosphorylation of Chk1 is also cell‐cycle specific, occurring primarily in late S phase and G 2 , but not during M/G 1 or early S phase. We have also isolated and characterized a temperature‐sensitive allele of rad3 . Rad3 functions differently depending on which checkpoint pathway is activated. Following DNA damage, rad3 is required to initiate but not maintain the Chk1 response. When DNA replication is inhibited, rad3 is required for both initiation and maintenance of the Cds1 response. We have identified a strong genetic interaction between rad3 and cds1 , and biochemical evidence shows a physical interaction is possible between Rad3 and Cds1, and between Rad3 and Chk1 in vitro . Together, our results highlight the cell‐cycle specificity of the DNA structure‐dependent checkpoint response and identify distinct roles for Rad3 in the different checkpoint responses.