This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Varrin, A. E. Articles by Duncker, B. P. Search for Related Content PubMed PubMed Citation Articles by Varrin, A. E. Articles by Duncker, B. P.

A Mutation in Dbf4 Motif M Impairs Interactions with DNA Replication Factors and Confers Increased Resistance to Genotoxic Agents

Department of Biology, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1

Received 1 November 2004/ Returned for modification 24 January 2005/ Accepted 10 June 2005

Dbf4/Cdc7 is required for DNA replication in Saccharomyces cerevisiae and appears to be a target in the S-phase checkpoint. Previously, a 186-amino-acid Dbf4 region that mediates interactions with both the origin recognition complex and Rad53 was identified. We now show this domain also mediates the association between Dbf4 and Mcm2, a key Dbf4/Cdc7 phosphorylation target. Two conserved sequences, the N and M motifs, have been identified within this Dbf4 region. Removing motif M (Dbf4M) impairs the ability of Dbf4 to support normal cell cycle progression and abrogates the Dbf4-Mcm2 association but has no effect on the Dbf4-Rad53 interaction. In contrast, deleting motif N (Dbf4N) does not affect the essential function of Dbf4, disrupts the Dbf4-Rad53 interaction, largely preserves the Dbf4-Mcm2 association, and renders the cells hypersensitive to genotoxic agents. Surprisingly, Dbf4M interacts strongly with Orc2, while Dbf4N does not. The DBF4 allele dna52-1 was cloned and sequenced, revealing a single point mutation within the M motif. This mutant is unable to maintain interactions with either Mcm2 or Orc2 at the semipermissive temperature of 30°C, while the interaction with Rad53 is preserved. Furthermore, this mutation confers increased resistance to genotoxic agents, which we propose is more likely due to a role for Dbf4 in the resumption of fork progression following checkpoint-induced arrest than prevention of late origin firing. Thus, the alteration of the M motif may facilitate the role of Dbf4 as a checkpoint target.

This article has been cited by other articles:

• Tenca, P., Brotherton, D., Montagnoli, A., Rainoldi, S., Albanese, C., Santocanale, C. (2007). Cdc7 Is an Active Kinase in Human Cancer Cells Undergoing Replication Stress. J. Biol. Chem. 282: 208-215 [Abstract] [Full Text]  
• Gabrielse, C., Miller, C. T., McConnell, K. H., DeWard, A., Fox, C. A., Weinreich, M. (2006). A Dbf4p BRCA1 C-Terminal-Like Domain Required for the Response to Replication Fork Arrest in Budding Yeast. Genetics 173: 541-555 [Abstract] [Full Text]