The C-terminal Region and SUMOylation of Cockayne Syndrome Group B Protein Play Critical Roles in Transcription-coupled Nucleotide Excision Repair.
Cockayne syndrome (CS) is a recessive disorder that results in deficiencies in transcription-coupled nucleotide excision repair (TC-NER), a subpathway of nucleotide excision repair, and cells from CS patients exhibit hypersensitivity to UV light. CS group B protein (CSB), which is the gene product of one of the genes responsible for ... CS, belongs to the SWI2/SNF2 DNA-dependent ATPase family and has an ATPase domain and an ubiquitin-binding domain (UBD) in the central region and the C-terminal region, respectively. The C-terminal region containing the UBD is essential for the functions of CSB. In this study, we generated several CSB deletion mutants and analyzed the functions of the C-terminal region of CSB in TC-NER. Not only the UBD but also the C-terminal 30-amino acid residues were required for UV light resistance and TC-NER. This region was needed for the interaction of CSB with RNA polymerase II, the translocation of CS group A protein to the nuclear matrix, and the association of CSB with chromatin after UV irradiation. CSB was modified by small ubiquitin-like modifier 2/3 in a UV light-dependent manner. This modification was abolished in a CSB mutant lacking the C-terminal 30 amino acid residues. However, the substitution of lysine residues in this region with arginine did not affect SUMOylation or TC-NER. By contrast, substitution of a lysine residue in the N-terminal region with arginine decreased SUMOylation and resulted in cells with defects in TC-NER. These results indicate that both the most C-terminal region and SUMOylation are important for the functions of CSB in TC-NER.
Mesh Terms:
Amino Acid Substitution, Blotting, Western, Cell Line, DNA Breaks, DNA Helicases, DNA Repair, DNA Repair Enzymes, Fibroblasts, Gene Deletion, Humans, Immunoprecipitation, Lysine, Mutation, Poly-ADP-Ribose Binding Proteins, Protein Interaction Domains and Motifs, Radiation Tolerance, Recombinant Fusion Proteins, Recombinant Proteins, Small Ubiquitin-Related Modifier Proteins, Sumoylation, Transcription, Genetic, Ubiquitins, Ultraviolet Rays
Amino Acid Substitution, Blotting, Western, Cell Line, DNA Breaks, DNA Helicases, DNA Repair, DNA Repair Enzymes, Fibroblasts, Gene Deletion, Humans, Immunoprecipitation, Lysine, Mutation, Poly-ADP-Ribose Binding Proteins, Protein Interaction Domains and Motifs, Radiation Tolerance, Recombinant Fusion Proteins, Recombinant Proteins, Small Ubiquitin-Related Modifier Proteins, Sumoylation, Transcription, Genetic, Ubiquitins, Ultraviolet Rays
J. Biol. Chem.
Date: Jan. 15, 2016
PubMed ID: 26620705
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