During cell division, sister chromatid pairs are held together by cohesin and are bi-oriented on the mitotic spindle before their separation and segregation are triggered by the anaphase-promoting complex/cyclosome (APC/C), a ubiquitin ligase. Shugoshins are conserved centromeric proteins that are necessary for proper bi-orientation; in some cells, they also protect centromeric cohesin by recruiting protein phosphatase 2A (PP2A), which dephosphorylates cohesin, thus preventing its cleavage. During mitosis, shugoshin levels drop drastically, suggesting that their destruction is important for their inactivation, but it remains unclear exactly how their function is regulated. In this study (p. 4974), Heather Eshleman and David Morgan investigate the role and regulation of Sgo1, the only shugoshin in the budding yeast Saccharomyces cerevisiae. They first show that Sgo1 is a target of the APC/C; its degradation is mediated by an unusual D-box-related motif near the C-terminus. Mutation of this motif stabilises the protein but does not prevent its removal from the centromere before anaphase onset. Instead, removal of both wild-type and mutant Sgo1 occurs once the sister chromatids have properly bi-oriented on the spindle. The authors also show that Sgo1 recruits the PP2A regulatory subunit Rts1 prior to bi-orientation and that tethering of Rts1 to pericentromeric chromatin bypasses the requirement for Sgo1. Taken together, these results indicate that the main role of Sgo1 is to recruit Rts1 to the centrosome in early mitosis to ensure accurate bi-orientation of sister chromatids.
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IN THIS ISSUE| 15 November 2014
Role of Sgo1 in sister chromatid bi-orientation
Online Issn: 1477-9137
Print Issn: 0021-9533
© 2014. Published by The Company of Biologists Ltd
J Cell Sci (2014) 127 (22): e2204.
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Role of Sgo1 in sister chromatid bi-orientation. J Cell Sci 15 November 2014; 127 (22): e2204. doi:
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