title: Novel XPG (ERCC5) mutations affect DNA repair and cell survival after ultraviolet but not oxidative stress.
abstract: Nucleotide excision repair (NER) is the most flexible of all known DNA-repair mechanisms, and XPG is a 3'-endonuclease that participates in NER. Mutations in this gene (ERCC5) may result in the human syndrome xeroderma pigmentosum (XP) and, in some cases, in the complex phenotype of Cockayne syndrome (CS). Two Brazilian XP siblings, who were mildly affected, were investigated and classified into the XP-G group. The cells from these patients were highly ultraviolet (UV) sensitive but not sensitive to photosensitized methylene blue, an agent that causes oxidative stress. This phenotype is in contrast to XP-G/CS cells, which are highly sensitive to this oxidative agent. Sequencing revealed a compound heterozygous genotype with two novel missense mutations: c.83C>A (p.Ala28Asp) and c.2904G>C (p.Trp968Cys). The first mutation maps to the catalytic site of the XPG protein, whereas the second may compromise binding to DNA. Functional assays indicated that the mutated alleles were unable to perform the complete repair of UV-irradiated plasmids; however, full correction was observed for oxidatively damaged plasmids. Therefore, the XP phenotype of these patients is caused by novel missense mutations that specifically affect DNA repair for UV- but not oxidative-stress-induced DNA damage, and implications for XP versus XP/CS phenotype are discussed.
authors.affiliation: Department of Microbiology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP, Brazil.
authors.forename: Daniela T
authors.initials: DT
authors.lastname: Soltys
authors.forename: Clarissa R R
authors.initials: CR
authors.lastname: Rocha
authors.forename: Letícia K
authors.initials: LK
authors.lastname: Lerner
authors.forename: Tiago A
authors.initials: TA
authors.lastname: de Souza
authors.forename: Veridiana
authors.initials: V
authors.lastname: Munford
authors.forename: Fernanda
authors.initials: F
authors.lastname: Cabral
authors.forename: Tiziana
authors.initials: T
authors.lastname: Nardo
authors.forename: Miria
authors.initials: M
authors.lastname: Stefanini
authors.forename: Alain
authors.initials: A
authors.lastname: Sarasin
authors.forename: Januário B
authors.initials: JB
authors.lastname: Cabral-Neto
authors.forename: Carlos F M
authors.initials: CF
authors.lastname: Menck
mesh_terms: D000293:Adolescent; D000483:Alleles; D000595:Amino Acid Sequence; D001938:Brazil; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects*; D003001:Cloning, Molecular; D003057:Cockayne Syndrome / Q000235:genetics; D004249:DNA Damage / Q000528:radiation effects; D004260:DNA Repair / Q000528:radiation effects*; D004268:DNA-Binding Proteins / Q000235:genetics*; D004720:Endonucleases / Q000235:genetics*; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000528:radiation effects; D006579:Heterozygote; D006801:Humans; D008297:Male; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D009687:Nuclear Proteins / Q000235:genetics*; D018384:Oxidative Stress / Q000528:radiation effects; D010641:Phenotype; D011487:Protein Conformation; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014157:Transcription Factors / Q000235:genetics*; D014466:Ultraviolet Rays; D014983:Xeroderma Pigmentosum / Q000235:genetics; D055815:Young Adult; D000099250:DNA Excision Repair Protein ERCC-5
chemical_list: D004268:DNA-Binding Proteins; D004720:Endonucleases; D009687:Nuclear Proteins; D014157:Transcription Factors; D000099250:DNA Excision Repair Protein ERCC-5