Essential role of Ubr11, but not Ubr1, as an N-end rule ubiquitin ligase in Schizosaccharomyces pombe
Article first published online: 28 NOV 2012
Copyright © 2012 John Wiley & Sons, Ltd.
Volume 30, Issue 1, pages 1–11, January 2013
How to Cite
Fujiwara, H., Tanaka, N., Yamashita, I. and Kitamura, K. (2013), Essential role of Ubr11, but not Ubr1, as an N-end rule ubiquitin ligase in Schizosaccharomyces pombe. Yeast, 30: 1–11. doi: 10.1002/yea.2936
- Issue published online: 24 JAN 2013
- Article first published online: 28 NOV 2012
- Accepted manuscript online: 31 OCT 2012 10:28PM EST
- Manuscript Accepted: 18 OCT 2012
- Manuscript Received: 21 SEP 2012
- UBR ubiquitin ligase;
- N-end rule pathway;
- Sz. pombe
The N-end rule pathway degrades proteins bearing a destabilization-inducing amino acid at the N-terminus. In this proteolytic system, Ubr ubiquitin ligases recognize and ubiquitylate substrates intended for degradation. Schizosaccharomyces pombe has two similar Ubr proteins, Ubr1 and Ubr11. Both proteins have unique roles in various cellular processes, although the ubr1∆ strain shows more severe defects. However, their involvement in the N-end rule pathway is unclear, and even the N-end rule pathway-dependent proteolytic activity has not been demonstrated in Sz. pombe. Here, we show that: (a) Sz. pombe has the N-end rule pathway in which only Ubr11, but not Ubr1, is responsible; and (b) the C-terminal fragment of the meiotic cohesin Rec8 (denoted as Rec8c) generated by separase-mediated cleavage is an endogenous substrate of the N-end rule pathway. Forced overexpression of stable Rec8c was deleterious in mitosis and caused a loss of the mini-chromosome. In unperturbed mitosis without overexpression, the rate of mini-chromosome loss was five-fold higher in the ubr11∆ strain. Since Rec8 is normally produced in meiosis, we examined whether meiosis and sporulation were affected in the ubr11∆ strain. In unperturbed meiosis, chromosome segregation occurred almost normally and viable spores were produced in the ubr11∆ cells, irrespective of the presence of undegraded endogenous Rec8c peptides. Copyright © 2012 John Wiley & Sons, Ltd.