DRC1, DNA replication and checkpoint protein 1, functions with DPB11 to control DNA replication and the S-phase checkpoint in Saccharomyces cerevisiae

Abstract

In addition to DNA polymerase complexes, DNA replication requires the coordinate action of a series of proteins, including regulators Cdc28͞Clb and Dbf4͞Cdc7 kinases, Orcs, Mcms, Cdc6, Cdc45, and Dpb11. Of these, Dpb11, an essential BRCT repeat protein, has remained particularly enigmatic. The Schizosaccharomyces pombe homolog of DPB11, cut5, has been implicated in the DNA replication checkpoint as has the POL2 gene with which DPB11 genetically interacts. Here we describe a gene, DRC1, isolated as a dosage suppressor of dpb11-1. DRC1 is an essential cell cycle-regulated gene required for DNA replication. We show that both Dpb11 and Drc1 are required for the S-phase checkpoint, including the proper activation of the Rad53 kinase in response to DNA damage and replication blocks. Dpb11 is the second BRCT-repeat protein shown to control Rad53 function, possibly indicating a general function for this class of proteins. DRC1 and DPB11 show synthetic lethality and reciprocal dosage suppression. The Drc1 and Dpb11 proteins physically associate and function together to coordinate DNA replication and the cell cycle.

Perpetuating the double helix: molecular machines at eukaryotic DNA replication origins

“…(78) ChIP experiments indicate that Dpb11 associated with origin sequences at the same time as Dpb2, the second subunit of polymerase e. Dpb11 association required MCMs and RPA and was, in turn, required for the recruitment of pol a/primase. (78) Loss of Dpb11 affected both S-phase progression and the S-phase checkpoint, (77,79) a surveillance mechanism that delays cell-cycle progression in the event of DNA damage or incomplete DNA replication.…”

“…Araki and colleagues have screened the S. cerevisiae genome for alleles displaying synthetic lethality with Dpb11 (''SLD'' phenotype). Some of the genes identified in this screen were previously known: (1) SLD1 is DPB3, which encodes the third subunit of pol e, (2) SLD2 is DRC1 (DNA replication and checkpoint protein 1), cloned independently using a similar approach, (79) (3) SLD4 is CDC45, and (4) SLD6 is checkpoint gene RAD53. SLD3 and SLD5 are interesting new genes (see below).…”

“…(79) Sld2/Drc1 protein physically interacts with Dpb11 and this interaction is regulated by phosphorylation. Mutation of all the preferred CDK phosphorylation sites in Sld2/Drc1 prevented the interaction with Dpb11 and impaired DNA replication.…”

Dpb11 activates the Mec1–Ddc2 complex

“…Specifically, Dpb11 acts as a molecular bridge between the Sld3-Cdc45-MCM helicase complex and the Sld2-DNA polymerase complex (16,17). Dpb11 also has a cell cycle checkpoint function and dpb11 mutants exhibit sensitivity to DNA damaging agents and replication stress (14,18). In metazoans, the Dpb11 homolog TopBP1 is a general activator of ATR.…”

Delineating the position ofrad4+/cut5+ within the DNA-structure checkpoint pathways inSchizosaccharomyces pombe

“…Despite this, the position of Rad4 within the checkpoint control pathways remains to be determined. Work in budding yeast has demonstrated that the Rad4 homologue, Dpb11, is required for activation of the Rad53 checkpoint kinase following engagement of the S-phase checkpoint (Wang and Elledge, 1999). More recently, Dpb11 has been shown to interact with Ddc1, S. pombe rad9 homologue, a result that implies a role for Dpb11 in the DNA damage checkpoint as well as the S-phase checkpoint (Wang and Elledge, 2002).…”