Publication Abstract from PubMed
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.
Structure of a Bmi-1-Ring1B polycomb group ubiquitin ligase complex.,Li Z, Cao R, Wang M, Myers MP, Zhang Y, Xu RM J Biol Chem. 2006 Jul 21;281(29):20643-9. Epub 2006 May 18. PMID:16714294[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
