Deyter GMR, Biggins S. The FACT complex interacts with the E3 ubiquitin ligase Psh1 to prevent ectopic localization of CENP-A.
Genes Dev 2014;
28:1815-26. [PMID:
25128498 PMCID:
PMC4197964 DOI:
10.1101/gad.243113.114]
[Citation(s) in RCA: 62] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Centromere identity and its epigenetic maintenance require the incorporation of the histone H3 variant CENP-A at centromeres. CENP-A mislocalization may disrupt chromatin-based processes and chromosome segregation. Here, Deyter and Biggins identify a role for the conserved chromatin-modifying complex FACT in preventing CENP-ACse4 mislocalization to euchromatin by mediating its proteolysis. The budding yeast Spt16 subunit of the FACT complex binds to Psh1, an E3 ubiquitin ligase that targets CENP-ACse4 for degradation. A Psh1 mutant that cannot associate with FACT has a reduced interaction with CENP-ACse4 in vivo.
Centromere identity and its epigenetic maintenance require the incorporation of a histone H3 variant called CENP-A at centromeres. CENP-A mislocalization to ectopic sites may disrupt chromatin-based processes and chromosome segregation, so it is important to uncover the mechanisms by which this variant is exclusively localized to centromeres. Here, we identify a role for the conserved chromatin-modifying complex FACT (facilitates chromatin transcription/transactions) in preventing budding yeast CENP-ACse4 mislocalization to euchromatin by mediating its proteolysis. The Spt16 subunit of the FACT complex binds to Psh1 (Pob3/Spt16/histone), an E3 ubiquitin ligase that targets CENP-ACse4 for degradation. The interaction between Psh1 and Spt16 is critical for both CENP-ACse4 ubiquitylation and its exclusion from euchromatin. We found that Psh1 cannot efficiently ubiquitylate CENP-ACse4 nucleosomes in vitro, suggesting that additional factors must facilitate CENP-ACse4 removal from chromatin in vivo. Consistent with this, a Psh1 mutant that cannot associate with FACT has a reduced interaction with CENP-ACse4 in vivo. Together, our data identify a previously unknown mechanism to maintain centromere identity and genomic stability through the FACT-mediated degradation of ectopically localized CENP-ACse4.
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