2H0D | pdb_00002h0d

Structure of a Bmi-1-Ring1B Polycomb Group Ubiquitin Ligase Complex.

(2006) J Biological Chem 281: 20643-20649

• PubMed: 16714294 Search on PubMed
• DOI: https://doi.org/10.1074/jbc.M602461200
• Primary Citation Related Structures: 
  2H0D


• PubMed Abstract: 
  

  Polycomb group proteins Bmi-1 and Ring1B are core subunits of the PRC1 complex, which plays important roles in the regulation of Hox gene expression, X-chromosome inactivation, tumorigenesis, and stem cell self-renewal. The RING finger protein Ring1B is an E3 ligase that participates in the ubiquitination of lysine 119 of histone H2A, and the binding of Bmi-1 stimulates the E3 ligase activity. We have mapped the regions of Bmi-1 and Ring1B required for efficient ubiquitin transfer and determined a 2.5-A structure of the Bmi-1-Ring1B core domain complex. The structure reveals that Ring1B "hugs" Bmi-1 through extensive RING domain contacts and its N-terminal tail wraps around Bmi-1. The two regions of interaction have a synergistic effect on the E3 ligase activity. Our analyses suggest a model where the Bmi-1-Ring1B complex stabilizes the interaction between the E2 enzyme and the nucleosomal substrate to allow efficient ubiquitin transfer.

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Organizational Affiliation: 
• Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA.