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Evidence for a Cdc6p‐independent mitotic resetting event involving DNA polymerase α
Author(s) -
Desdouets Chantal,
Santocanale Corrado,
Drury Lucy S.,
Perkins Gordon,
Foiani Marco,
Plevani Paolo,
Diffley John F.X.
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/17.14.4139
Subject(s) - biology , dna polymerase , genetics , mitosis , polymerase , dna , event (particle physics) , computational biology , microbiology and biotechnology , physics , quantum mechanics
C.Desdouets and C.Santocanale contributed equally to this work Eukaryotic DNA replication is limited to once per cell cycle because cyclin‐dependent kinases (cdks), which are required to fire origins, also prevent re‐replication. Components of the replication apparatus, therefore, are ‘reset’ by cdk inactivation at the end of mitosis. In budding yeast, assembly of Cdc6p‐dependent pre‐replicative complexes (pre‐RCs) at origins can only occur during G 1 because it is blocked by cdk1 (Cdc28) together with B cyclins (Clbs). Here we describe a second, separate process which is also blocked by Cdc28/Clb kinase and, therefore, can only occur during G 1 ; the recruitment of DNA polymerase α‐primase (pol α) to chromatin. The recruitment of pol α to chromatin during G 1 is independent of pre‐RC formation since it can occur in the absence of Cdc6 protein. Paradoxically, overproduction of Cdc6p can drive both dephosphorylation and chromatin association of pol α. Overproduction of a mutant in which the N‐terminus of Cdc6 has been deleted is unable to drive pol α chromatin binding. Since this mutant is still competent for pre‐RC formation and DNA replication, we suggest that Cdc6p overproduction resets pol α chromatin binding by a mechanism which is independent of that used in pre‐RC assembly.