Identifying a borealin component of the yeast chromosome passenger complex
Identifying a borealin component of the
yeast chromosome passenger complex..
Originally published as MBC in Press, 10.1091/mbc.E09-04-0289 on July 1, 2009
Vol. 20, Issue 16, 3646-3659, August 15, 2009
A Link between Aurora Kinase and Clp1/Cdc14 Regulation Uncovered by the Identification of a Fission Yeast Borealin-Like Protein
*Howard Hughes Medical Institute and Department of Cell and
Developmental Biology, Vanderbilt University School of Medicine,
Nashville, TN 37232; and Department of Molecular and Cellular Biochemistry and Center for Structural Biology, University of Kentucky, Lexington, KY 40536
Submitted April 9, 2009;
Revised June 18, 2009;
Accepted June 19, 2009
Monitoring Editor: Daniel J. Lew
ABSTRACT
The chromosomal passenger complex (CPC) regulates various events in cell division. This complex is composed of a catalytic subunit, Aurora B kinase, and three nonenzymatic subunits, INCENP, Survivin, and Borealin. Together, these four subunits interdependently regulate CPC function, and they are highly conserved among eukaryotes. However, a Borealin homologue has never been characterized in the fission yeast, Schizosaccharomyces pombe. Here, we isolate a previously uncharacterized S. pombe protein through association with the Cdc14 phosphatase homologue, Clp1/Flp1, and identify it as a Borealin-like member of the CPC. Nbl1 (novel Borealin-like 1) physically associates with known CPC components, affects the kinase activity and stability of the S. pombe Aurora B homologue, Ark1, colocalizes with known CPC subunits during mitosis, and shows sequence similarity to human Borealin. Further analysis of the Clp1–Nbl1 interaction indicates that Clp1 requires CPC activity for proper accumulation at the contractile ring (CR). Consistent with this, we describe negative genetic interactions between mutant alleles of CPC and CR components. Thus, this study characterizes a fission yeast Borealin homologue and reveals a previously unrecognized connection between the CPC and the process of cytokinesis in S. pombe.