Ubc1 turnover contributes to the spindle assembly checkpoint in Saccharomyces cerevisiae

• Published in: G3 : genes - genomes - genetics Vol. 11; no. 12
• Main Authors: Arsenault, Heather E, Ghizzoni, Julie M, Leech, Cassandra M, Diers, Anne R, Gesta, Stephane, Vishnudas, Vivek K, Narain, Niven R, Sarangarajan, Rangaprasad, Benanti, Jennifer A
• Format: Journal Article
• Language: English
• Published: England Oxford University Press 08-12-2021
• Subjects: Anaphase; Anaphase-Promoting Complex-Cyclosome - genetics; Cdc20 Proteins; Cell Cycle Proteins - genetics; Investigation; M Phase Cell Cycle Checkpoints; Mitosis; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae Proteins - genetics; Spindle Apparatus; Ubiquitin-Conjugating Enzymes - genetics; mitosis; anaphase-promoting complex; spindle assembly checkpoint
• ISSN: 2160-1836; 2160-1836
• DOI: 10.1093/g3journal/jkab346

Abstract
The spindle assembly checkpoint protects the integrity of the genome by ensuring that chromosomes are properly attached to the mitotic spindle before they are segregated during anaphase. Activation of the spindle checkpoint results in inhibition of the Anaphase-Promoting Complex (APC), an E3 ubiquitin ligase that triggers the metaphase–anaphase transition. Here, we show that levels of Ubc1, an E2 enzyme that functions in complex with the APC, modulate the response to spindle checkpoint activation in Saccharomyces cerevisiae. Overexpression of Ubc1 increased resistance to microtubule poisons, whereas Ubc1 shut-off sensitized cells. We also found that Ubc1 levels are regulated by the spindle checkpoint. Checkpoint activation or direct APC inhibition led to a decrease in Ubc1 levels, charging, and half-life. Additionally, stabilization of Ubc1 prevented its down-regulation by the spindle checkpoint and increased resistance to checkpoint-activating drugs. These results suggest that down-regulation of Ubc1 in response to spindle checkpoint signaling is necessary for a robust cell cycle arrest.