The CENP-B homolog, Abp1, interacts with the initiation protein Cdc23 (MCM10) and is required for efficient DNA replication in fission yeast
1 University of Miami School of Medicine, Department of Molecular and Cellular Pharmacology, P.O. Box 016189, Miami, FL, 33101, USA
2 Department of Applied Bioscience and Biotechnology, Faculty of Life and Environmental Science, Shimane University, Matsue, 690-8504, Shimane, Japan
3 Institute for Virus Research, Kyoto University, Sakyo-ku, Kyoto, 606-8507, Japan
Cell Division 2006, 1:27 doi:10.1186/1747-1028-1-27Published: 17 November 2006
Abp1, and the closely related Cbh1 and Cbh2 are homologous to the human centromere-binding protein CENP-B that has been implicated in the assembly of centromeric heterochromatin. Fission yeast cells lacking Abp1 show an increase in mini-chromosome instability suggesting that Abp1 is important for chromosome segregation and/or DNA synthesis. Here we show that Abp1 interacts with the DNA replication protein Cdc23 (MCM10) in a two-hybrid assay, and that the Δabp1 mutant displays a synthetic phenotype with a cdc23 temperature-sensitive mutant. Moreover, genetic interactions were also observed between abp1+ and four additional DNA replication initiation genes cdc18+, cdc21+, orc1+, and orc2+. Interestingly, we find that S phase is delayed in cells deleted for abp1+ when released from a G1 block. However, no delay is observed when cells are released from an early S phase arrest induced by hydroxyurea suggesting that Abp1 functions prior to, or coincident with, the initiation of DNA replication.