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Molecular and Cellular Biology, October 2005, p. 9000-9015, Vol. 25, No. 20
0270-7306/05/$08.00+0 doi:10.1128/MCB.25.20.9000-9015.2005
Copyright © 2005, American Society for Microbiology. All Rights Reserved.
Julie M. Bailis,
Joel D. Leverson,
Eliana B. Gómez,
Susan L. Forsburg,
and
Tony Hunter*
Molecular and Cell Biology Laboratory, The Salk Institute for Biological Studies, La Jolla, California 92037
Received 20 January 2005/ Returned for modification 7 March 2005/ Accepted 21 July 2005
Fission yeast Bir1p/Cut17p/Pbh1p, the homolog of human Survivin, is a conserved chromosomal passenger protein that is required for cell division and cytokinesis. To study how Bir1p promotes accurate segregation of chromosomes, we generated and analyzed a temperature-sensitive allele, bir1-46, and carried out genetic screens to find genes that interact with bir1+. We identified Psf2p, a component of the GINS complex required for DNA replication initiation, as a high-copy-number suppressor of the bir1-46 growth defect. Loss of Psf2p function by depletion or deletion or by use of a temperature-sensitive allele, psf2-209, resulted in chromosome missegregation that was associated with mislocalization of Bir1p. We also found that the human homolog of Psf2p, PSF2, was required for proper chromosome segregation. In addition, we observed that high-copy-number expression of Pic1p, the fission yeast homolog of INCENP (inner centromere protein), suppressed bir1-46. Pic1p exhibited a localization pattern typical of chromosomal passenger proteins. Deletion of pic1+ caused chromosome missegregation phenotypes similar to those of bir1-46. Our data suggest that Bir1p and Pic1p act as part of a conserved chromosomal passenger complex and that Psf2p/GINS indirectly affects the localization and function of this complex in chromosome segregation, perhaps through an S-phase role in centromere replication.
¶ Supplemental material for this article may be found at http://mcb.asm.org/.
H.-K.H. and J.M.B. contributed equally to this study.
Present address: Abbott Laboratories, Abbott Park, IL 60064.
Present address: Molecular and Computational Biology Section, University of Southern California, Los Angeles, CA 90089.
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