title: The CENP-B homolog, Abp1, interacts with the initiation protein Cdc23 (MCM10) and is required for efficient DNA replication in fission yeast.
abstract: 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 Deltaabp1 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.
authors.affiliation: University of Miami School of Medicine, Department of Molecular and Cellular Pharmacology, Miami, FL 33101, USA. alocovei@molbio.med.miami.edu
authors.forename: Alexandra M
authors.initials: AM
authors.lastname: Locovei
authors.forename: Maria-Grazia
authors.initials: MG
authors.lastname: Spiga
authors.forename: Katsunori
authors.initials: K
authors.lastname: Tanaka
authors.forename: Yota
authors.initials: Y
authors.lastname: Murakami
authors.forename: Gennaro
authors.initials: G
authors.lastname: D'Urso