High impact information on UBP8

• Deletion of Ubp8 lowered transcription of SAGA-regulated genes, and the severity of this defect was exacerbated by codeletion of the Gcn5 acetyltransferase within SAGA [1].
• We show that Ubp8, a component of the SAGA acetylation complex, is required for SAGA-mediated deubiquitylation of histone H2B in vitro [1].
• In addition, disruption of either ubiquitylation or Ubp8-mediated deubiquitylation of H2B resulted in altered levels of gene-associated H3 Lys 4 methylation and Lys 36 methylation, which have both been linked to transcription [1].
• Transcriptional activation via sequential histone H2B ubiquitylation and deubiquitylation, mediated by SAGA-associated Ubp8 [1].
• We compare Ubp10 to Ubp8, the SAGA-associated H2B deubiquitylase involved in gene activation, and show that telomeric and gene-silencing functions are specific to Ubp10 [2].

Biological context of UBP8

• Like that at GAL1, H3-K4 methylation is increased at the PHO84 core promoter in the UBP8 deletion mutant [3].
• Using mutagenesis, we identified a putative zinc (Zn) binding domain within Ubp8 as being critical for the association with SAGA [4].

Associations of UBP8 with chemical compounds

• Furthermore, trimethylation of H3 at lysine 4 within the UAS increases significantly under activating conditions, and remarkably, Ubp8 is shown to have a role in regulating the methylation status of this residue [5].

Other interactions of UBP8

• SAGA purified from a sgf11 Delta deletion strain has reduced amounts of Ubp8p, and a ubp8 Delta deletion strain shows changes in transcription similar to those seen with the sgf11 Delta deletion strain [6].
• SAGA combines proteins involved in interactions with DNA-bound activators and TATA-binding protein (TBP), as well as enzymes for histone acetylation (Gcn5) and histone deubiquitylation (Ubp8) [4].
• The recent finding that the removal of the ubiquitin group from H2B is performed by a component of SAGA, Ubp8, is intriguing as it assigns two posttranslation modification processes to one complex [7].
• Here we show that a putative deubiquitinating enzyme, Ubp8, is a structurally nonessential component of both the Spt-Ada-Gcn5-acetyltransferase (SAGA) and SAGA-like (SLIK) histone acetyltransferase (HAT) complexes in yeast [5].

References