Structural Transitions of the RING1B C-Terminal Region upon Binding the Polycomb cbox Domain
| Autor: | Chongwoo A. Kim, Udayar Ilangovan, Eileen M. Lafer, Virgil Schirf, Renjing Wang, Patricia M. Schwarz, Andrew P. Hinck, Angela K. Robinson, Borries Demeler |
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| Rok vydání: | 2008 |
| Předmět: |
Conformational change
Magnetic Resonance Spectroscopy Multiprotein complex Ubiquitin-Protein Ligases Molecular Sequence Data Polycomb-Group Proteins macromolecular substances Plasma protein binding Biology Models Biological Biochemistry DNA-binding protein Article Conserved sequence Protein structure Humans Amino Acid Sequence Polycomb Repressive Complex 1 Genetics Sequence Homology Amino Acid Nuclear magnetic resonance spectroscopy Surface Plasmon Resonance Protein Structure Tertiary DNA-Binding Proteins Repressor Proteins Biophysics Electrophoresis Polyacrylamide Gel Ultracentrifugation Protein Binding Binding domain |
| Zdroj: | Biochemistry. 47:8007-8015 |
| ISSN: | 1520-4995 0006-2960 |
| Popis: | Polycomb group (PcG) proteins are required for maintaining cell identity and stem cell self-renewal. RING1B and Polycomb (Pc) are two components of a multiprotein complex called polycomb repression complex 1 (PRC1) that is essential for establishing and maintaining long-term repressed gene states. Here we characterize the interaction between the C-terminal region of RING1B (C-RING1B) and the Pc cbox domain. The C-RING1B-cbox interaction displays a 1:1 stoichiometry with dissociation constants ranging from 9.2 to 180 nM for the different Pc orthologues. NMR analysis of C-RING1B alone reveals line broadening. However, when it is in complex with the cbox domain, there is a striking change to the NMR spectrum indicative of conformational tightening. This conformational change may arise from the organization of the C-RING1B subdomains. The C-terminal regions of all PcG RING1 proteins are composed of two stretches of conserved sequences separated by a variable linker sequence. While the entire C-RING1B region is required for cbox binding, the N- and C-terminal halves of C-RING1B can be separated and are able to interact, suggesting the presence of an intramolecular interaction within C-RING1B. The flexibility within the C-RING1B structure allowing transitions between the intramolecular bound and unbound states may cause the broadened peaks of the C-RING1B NMR spectrum. Binding the cbox domain stabilizes C-RING1B, whereby broadening is eliminated. The presence of flexible regions could allow C-RING1B to bind a variety of different factors, ultimately recruiting RING1B and its associated PcG proteins to different genomic loci. |
| Databáze: | OpenAIRE |
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