CENTROMERE DNA-BINDING PROTEIN FROM FISSION YEAST AFFECTS CHROMOSOME SEGREGATION AND HAS HOMOLOGY TO HUMAN CENP-B

Genetic and biochemical strategies have been used to identify Schizosa ccharomyces pombe proteins with roles in centromere function. One prot ein, identified by both approaches, shows significant homology to the human centromere DNA-binding protein, CENP-B, and is identical to Abpl p (autonomously replicating sequence-binding protein 1) (Murakami, Y., J.A. Huberman, and J. Hurwitz. 1996. Proc. Natl. Acad. Sci. USA. 93:5 02-507). Abplp binds in vitro specifically to at least three sites in centromeric central core DNA of S. pombe chromosome II (cc2). Overexpr ession of abp1 affects mitotic chromosome stability in S. pombe. Altho ugh inactivation of the abp1 gene is not lethal, the abp1 null strain displays marked mitotic chromosome instability and a pronounced meioti c defect. The identification of a CENP-B-related centromere DNA-bindin g protein in S. pombe strongly supports the hypothesis that fission ye ast centromeres are structurally and functionally related to the centr omeres of higher eukaryotes.