title: REX1, a novel gene required for DNA repair.
abstract: Nucleotide excision repair is a major pathway for repairing UV light-induced DNA damage in most organisms. Using insertional mutagenesis, we isolated a UV-sensitive mutant of Chlamydomonas reinhardtii that is blocked in the excision of cyclobutane pyrimidine dimers. The mutant is also sensitive to the alkylating agent, methyl methanesulphonate. We have cloned REX1, a novel gene that rescues the mutant. The gene is unusual in a eukaryotic organism in that it is predicted to encode two different proteins, a small protein (8.9 kDa) and a larger protein (31.8 kDa). Neither protein is homologous to known DNA repair proteins. Partial complementation is achieved with subclones of the gene encoding only the 8.9-kDa protein. The 8.9-kDa protein has homologues in many organisms including Saccharomyces cerevisiae, Arabidopsis, and humans. The 31.8-kDa protein appears to be less conserved. These findings may be of general importance for DNA repair in other organisms.
authors.affiliation: Cellular and Molecular Biology Group, The University of South Dakota, Vermillion, South Dakota 57069, USA.
authors.forename: Belgin
authors.initials: B
authors.lastname: Cenkci
authors.forename: Jason L
authors.initials: JL
authors.lastname: Petersen
authors.forename: Gary D
authors.initials: GD
authors.lastname: Small
mesh_terms: D020418:Algal Proteins; D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics*; D016825:Chlamydomonas reinhardtii / Q000235:genetics* / Q000528:radiation effects; D004260:DNA Repair / Q000235:genetics* / Q000528:radiation effects; D005091:Exons; D006801:Humans; D007438:Introns; D051379:Mice; D008969:Molecular Sequence Data; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics* / Q000528:radiation effects; D015183:Restriction Mapping; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014466:Ultraviolet Rays
chemical_list: D020418:Algal Proteins; D001426:Bacterial Proteins; D015800:Protozoan Proteins