The isolated C-terminal domain of Ring1B is a dimer made of stable, well-structured monomers.
The Ring1B is a core subunit protein of the PRC1 (polycomb repressive complex 1), which plays key roles in the regulation of the Homeobox gene expression, X-chromosome inactivation, stem cell self-renewal, and tumorigenesis. The C-terminal region of Ring1B interacts with RYBP, a transcriptional repressor in transiently transfected cells, and also with M33, another transcriptional repressor involved in mesoderm patterning. In this work, we show that the C-terminal domain of Ring1B, C-Ring1B, is a dimer in solution, with a dissociation constant of 200 microM, as shown by NMR, ITC, and analytical gel filtration. Each monomer is stable at physiological conditions in a wide pH range ( approximately 5 kcal mol-1 at 298 K), with a well-formed core and a spherical shape. The dimer has a high content of alpha-helix and beta-sheet, as indicated by FTIR spectra, and it is formed by the mutual docking of the preformed folded monomers. Since the C-terminal region is important for interaction with other proteins of the PRC1, the dimerization and the presence of those well-structured monomers might be a form of regulation.
Czypionka
Anna
A
Instituto de Biología Molecular y Celular, Universidad Miguel Hernández, 03202 Elche (Alicante), Spain.
de los Paños
Olga Ruiz
OR
Mateu
Mauricio G
MG
Barrera
Francisco N
FN
Hurtado-Gómez
Estefanía
E
Gómez
Javier
J
Vidal
Miguel
M
Neira
José L
JL
D000595:Amino Acid Sequence; D000818:Animals; D002850:Chromatography, Gel; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D019281:Dimerization; D006863:Hydrogen-Ion Concentration; D051379:Mice; D008969:Molecular Sequence Data; D063150:Polycomb Repressive Complex 1; D011485:Protein Binding; D011489:Protein Denaturation; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins; D044767:Ubiquitin-Protein Ligases
D004268:DNA-Binding Proteins; D012097:Repressor Proteins; D063150:Polycomb Repressive Complex 1; C489842:Rnf2 protein, mouse; D044767:Ubiquitin-Protein Ligases