Fdo1, Fkh1, Fkh2 and the Swi6-Mbp1 MBF complex regulate Mcd1 levels to impact eco1 rad61 cell growth in Saccharomyces cerevisiae

Abstract

Cohesins promote proper chromosome segregation, gene transcription, genomic architecture, DNA condensation, and DNA damage repair. Mutations in either cohesin subunit or regulatory genes can give rise to severe developmental abnormalities (such as Robert Syndrome and Cornelia de Lange Syndrome) and also are highly correlated with cancer. Despite this, little is known about cohesin regulation. Eco1 (ESCO2/EFO2 in humans) and Rad61 (WAPL in humans) represent two such regulators but perform opposing roles. Eco1 acetylation of cohesin during S phase, for instance, stabilizes cohesin-DNA binding to promote sister chromatid cohesion. On the other hand, Rad61 promotes the dissociation of cohesin from DNA. While Eco1 is essential,ECO1andRAD61co-deletion results in yeast cell viability, but only within a limited temperature range. Here, we report thateco1 rad61cell lethality is due to reduced levels of the cohesin subunit Mcd1. Results from a suppressor screen further reveals thatFDO1deletion rescues the temperature sensitive (ts) growth defects exhibited byeco1 rad61double mutant cells by increasing Mcd1 levels. Regulation ofMCD1expression, however, appears more complex. Elevated expression ofMBP1, which encodes a subunit of the MBF transcription complex, also rescueseco1 rad61cell growth defects. Elevated expression ofSWI6, however, which encodes the Mbp1-binding partner of MBF, exacerbateseco1 rad61cell growth and also abrogates the Mpb1-dependent rescue. Finally, we identify two additional transcription factors, Fkh1 and Fkh2, that impactMCD1expression. In combination, these findings provide new insights into the nuanced and multi-faceted transcriptional pathways that impactMCD1expression.