title: The isolated N terminus of Ring1B is a well-folded, monomeric fragment with native-like structure.
abstract: The Polycomb group (PcG) proteins assemble into Polycomb repressive complexes (PRCs), PRC1 and PRC2, which act as general transcriptional repressors. PRC1 comprises a variety of biochemical entities endowed with histone H2A monoubiquitylation activity conferred by really interesting new gene (RING) finger E3 ubiquitin ligases Ring1A and Ring1B. All PRC1 complexes contain Ring1 proteins which are essential for Polycomb epigenetic regulation. We have been able to express the isolated N-terminal region of Ring1B, N-Ring1B, comprising the first 221 residues of the 334-residue-long Ring1B. This fragment contains the 41-residue-long RING finger motif, and flanking sequences that form an interacting platform for PcG and non-PcG proteins. We found that the N-Ring1B is a well-folded, monomeric fragment, with native-like structure which unfolds irreversibly. The protein is capable of binding to an ubiquitin-conjugase protein (with an 85% of sequence similarity to the Ring1B physiological partner) with moderate affinity.
authors.affiliation: Departamento de Química-Física, Bioquímica y Química Inorgánica, Agrifood Campus of International Excellence (ceiA3), Universidad de Almería, 04120 Almería, Spain.
authors.forename: Ana Isabel
authors.initials: AI
authors.lastname: Martínez-Gómez
authors.forename: Sandra
authors.initials: S
authors.lastname: Villegas
authors.forename: David
authors.initials: D
authors.lastname: Aguado-Llera
authors.forename: Julio
authors.initials: J
authors.lastname: Bacarizo
authors.forename: Ana
authors.initials: A
authors.lastname: Cámara-Artigas
authors.forename: Miguel
authors.initials: M
authors.lastname: Vidal
authors.forename: José L
authors.initials: JL
authors.lastname: Neira
mesh_terms: D006801:Humans; D063150:Polycomb Repressive Complex 1 / Q000737:chemistry* / Q000378:metabolism*; D017510:Protein Folding; D055550:Protein Stability; D013057:Spectrum Analysis
chemical_list: D063150:Polycomb Repressive Complex 1; C489841:RNF2 protein, human
keywords: FTIR/NMR; binding; circular dichroism; fluorescence; protein folding; protein stability