title: SUMO-Targeted Ubiquitin Ligase (STUbL) Slx5 regulates proteolysis of centromeric histone H3 variant Cse4 and prevents its mislocalization to euchromatin.
abstract: Centromeric histone H3, CENP-ACse4, is essential for faithful chromosome segregation. Stringent regulation of cellular levels of CENP-ACse4restricts its localization to centromeres. Mislocalization of CENP-ACse4is associated with aneuploidy in yeast, flies and tumorigenesis in human cells; thus, defining pathways that regulate CENP-A levels is critical for understanding how mislocalization of CENP-A contributes to aneuploidy in human cancers. Previous work in budding yeast has shown that ubiquitination of overexpressed Cse4 by Psh1, an E3 ligase, partially contributes to proteolysis of Cse4. Here, we provide the first evidence that Cse4 is sumoylated by E3 ligases Siz1 and Siz2 in vivo and in vitro. Ubiquitination of Cse4 by Small Ubiquitin-related Modifier (SUMO)-Targeted Ubiquitin Ligase (STUbL) Slx5 plays a critical role in proteolysis of Cse4 and prevents mislocalization of Cse4 to euchromatin under normal physiological conditions. Accumulation of sumoylated Cse4 species and increased stability of Cse4 in slx5∆ strains suggest that sumoylation precedes ubiquitin-mediated proteolysis of Cse4. Slx5-mediated Cse4 proteolysis is independent of Psh1 since slx5∆ psh1∆ strains exhibit higher levels of Cse4 stability and mislocalization compared to either slx5∆ or psh1∆ strains. Our results demonstrate a role for Slx5 in ubiquitin-mediated proteolysis of Cse4 to prevent its mislocalization and maintain genome stability.
authors.affiliation: Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institute of Health, Bethesda, MD 20892.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Ohkuni
authors.affiliation: Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institute of Health, Bethesda, MD 20892.
authors.forename: Yoshimitsu
authors.initials: Y
authors.lastname: Takahashi
authors.affiliation: Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.
authors.forename: Alyona
authors.initials: A
authors.lastname: Fulp
authors.affiliation: Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.
authors.forename: Josh
authors.initials: J
authors.lastname: Lawrimore
authors.affiliation: Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institute of Health, Bethesda, MD 20892.
authors.forename: Wei-Chun
authors.initials: WC
authors.lastname: Au
authors.affiliation: Biology Department, The College of William & Mary, Williamsburg, VA 23187.
authors.forename: Nagesh
authors.initials: N
authors.lastname: Pasupala
authors.affiliation: Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institute of Health, Bethesda, MD 20892 Biology Department, The College of William & Mary, Williamsburg, VA 23187.
authors.forename: Reuben
authors.initials: R
authors.lastname: Levy-Myers
authors.affiliation: Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institute of Health, Bethesda, MD 20892.
authors.forename: Jack
authors.initials: J
authors.lastname: Warren
authors.affiliation: Guangzhou Institutes of Biomedicine and Health, Guangzhou, China, 510530.
authors.forename: Alexander
authors.initials: A
authors.lastname: Strunnikov
authors.affiliation: Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA 01655.
authors.forename: Richard E
authors.initials: RE
authors.lastname: Baker
authors.affiliation: Biology Department, The College of William & Mary, Williamsburg, VA 23187.
authors.forename: Oliver
authors.initials: O
authors.lastname: Kerscher
authors.affiliation: Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.
authors.forename: Kerry
authors.initials: K
authors.lastname: Bloom
authors.affiliation: Genetics Branch, Center for Cancer Research, National Cancer Institute, National Institute of Health, Bethesda, MD 20892.
authors.forename: Munira A
authors.initials: MA
authors.lastname: Basrai