S. pombe Pbh1p: an inhibitor of apoptosis domain containing protein is essential for chromosome segregation.

Institute of Molecular Agrobiology, The National University of Singapore, Singapore.
FEBS Letters (Impact Factor: 3.58). 11/1999; 460(1):187-90. DOI: 10.1016/S0014-5793(99)01329-0
Source: PubMed

ABSTRACT Proteins containing the baculovirus inhibitor of apoptosis repeats (BIR domains) have been identified in a wide range of species. BIR domain containing proteins are thought to inhibit caspases and thereby cause inhibition of apoptosis. A BIR domain containing protein has been recently identified by the Schizosaccharomyces pombe genome sequencing project. However, caspase-like proteins have not been found in yeasts, suggesting that the BIR domain containing proteins might play a fundamental role in cell regulation, in addition to their well-characterized role in inhibition of apoptosis. In this study, we have characterized Pbh1p, an S. pombe BIR domain containing protein. Construction and analysis of a null mutant in pbh1+ revealed that pbh1+ is essential for cell viability. Moreover, cells devoid of Pbh1p are defective in chromosome condensation and chromosome segregation. Thus, proper chromosome segregation requires the function of Pbh1p. Over-production of Pbh1p led to abnormalities in mitosis and cytokinesis, suggesting that the levels of Pbh1p are important for regulation of mitosis and cytokinesis.

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