Download MendeleyBMI1-RING1B is an autoinhibited RING E3 ubiquitin ligase.
Taherbhoy, A.M., Huang, O.W., Cochran, A.G.(2015) Nat Commun 6: 7621-7621
- PubMed: 26151332
- DOI: https://doi.org/10.1038/ncomms8621
- Primary Citation of Related Structures:
4S3O - PubMed Abstract:
Polycomb repressive complex 1 (PRC1) is required for ubiquitination of histone H2A lysine 119, an epigenetic mark associated with repression of genes important in developmental regulation. The E3 ligase activity of PRC1 resides in the RING1A/B subunit when paired with one of six PCGF partners. The best known of these is the oncogene BMI1/PCGF4. We find that canonical PRC1 E3 ligases such as PCGF4-RING1B have intrinsically very low enzymatic activity compared with non-canonical PRC1 RING dimers. The structure of a high-activity variant in complex with E2 (PCGF5-RING1B-UbcH5c) reveals only subtle differences from an earlier PCGF4 complex structure. However, two charged residues present in the modelled interface with E2-conjugated ubiquitin prove critical: in BMI1/PCGF4, these residues form a salt bridge that may limit efficient ubiquitin transfer. The intrinsically low activity of the PCGF4-RING1B heterodimer is offset by a relatively favourable interaction with nucleosome substrates, resulting in an efficient site-specific monoubiquitination.
Organizational Affiliation:
Department of Early Discovery Biochemistry, Genentech Inc., 1 DNA Way, South San Francisco, California 94080, USA.
