Role for yeast inhibitor of apoptosis (IAP)-like proteins in cell division

Role for yeast inhibitor of apoptosis (IAP)-like proteins in cell division

^*The Walter and Eliza Hall Institute of Medical Research, Post Office Royal Melbourne Hospital, Victoria 3050, Australia; ^†Department of Biochemistry and Genetics, La Trobe University, Bundoora, Victoria 3083, Australia; ^‡Research Division, Peter MacCallum Cancer Institute, St. Andrew’s Place, East Melbourne, Victoria 3002, Australia; and ^§Baker Medical Research Institute, P.O. Box 6492, St. Kilda Road Central, Melbourne, Victoria 8008, Australia

Communicated by Gustav J. V. Nossal, University of Melbourne, Parkville, Australia (received for review May 18, 1999)

Abstract

Inhibitors of apoptosis (IAPs) are a family of proteins that bear baculoviral IAP repeats (BIRs) and regulate apoptosis in vertebrates and Drosophila melanogaster. The yeasts Saccharomyces cerevisiae and Schizosaccharomyces pombe both encode a single IAP, designated BIR1 and bir1, respectively, each of which bears two BIRs. In rich medium, BIR1 mutant S. cerevisiae underwent normal vegetative growth and mitosis. Under starvation conditions, however, BIR1 mutant diploids formed spores inefficiently, instead undergoing pseudohyphal differentiation. Most spores that did form failed to survive beyond two divisions after germination. bir1 mutant S. pombe spores also died in the early divisions after spore germination and became blocked at the metaphase/anaphase transition because of an inability to elongate their mitotic spindle. Rather than inhibiting caspase-mediated cell death, yeast IAP proteins have roles in cell division and appear to act in a similar way to the IAPs from Caenorhabditis elegans and the mammalian IAP Survivin.

Footnotes

↵ ¶ To whom reprint requests should be addressed. E-mail: vaux{at}wehi.edu.au.
ABBREVIATIONS:

IAP,

inhibitor of apoptosis;

BIR,

baculoviral IAP repeat;

SM,

sporulation medium;

DAPI,

4′,6-diamidino-2-phenylindole