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Degradation of a cohesin subunit by the N-end rule pathway is essential for chromosome stability.

Nature | Apr 19, 2001

http://www.ncbi.nlm.nih.gov/pubmed/11309624

Cohesion between sister chromatids is established during DNA replication and depends on a protein complex called cohesin. At the metaphase-anaphase transition in the yeast Saccharomyces cerevisiae, the ESP1-encoded protease separin cleaves SCC1, a subunit of cohesin with a relative molecular mass of 63,000 (Mr 63K). The resulting 33K carboxy-terminal fragment of SCC1 bears an amino-terminal arginine-a destabilizing residue in the N-end rule. Here we show that the SCC1 fragment is short-lived (t1/2 approximately 2 min), being degraded by the ubiquitin/proteasome-dependent N-end rule pathway. Overexpression of a long-lived derivative of the SCC1 fragment is lethal. In ubr1Delta cells, which lack the N-end rule pathway, we found a highly increased frequency of chromosome loss. The bulk of increased chromosome loss in ubr1Delta cells is caused by metabolic stabilization of the ESP1-produced SCC1 fragment. This fragment is the first physiological substrate of the N-end rule pathway that is targeted through its N-terminal residue. A number of yeast proteins bear putative cleavage sites for the ESP1 separin, suggesting other physiological substrates and functions of the N-end rule pathway.

Pubmed ID: 11309624 RIS Download

Mesh terms: Anaphase | Arginine | Cell Cycle Proteins | Cell Division | Chromatids | Chromosomal Proteins, Non-Histone | Chromosome Segregation | Chromosomes, Fungal | Cysteine Endopeptidases | Dipeptides | Endopeptidases | Fungal Proteins | Half-Life | Ligases | Multienzyme Complexes | Nuclear Proteins | Peptide Fragments | Phosphoproteins | Proteasome Endopeptidase Complex | Recombinant Fusion Proteins | Saccharomyces cerevisiae | Saccharomyces cerevisiae Proteins | Separase | Ubiquitin-Protein Ligases | Ubiquitins