title: A novel SMC protein complex in Schizosaccharomyces pombe contains the Rad18 DNA repair protein.
abstract: In Schizosaccharomyces pombe, rad18 is an essential gene involved in the repair of DNA damage produced by ionizing radiation and in tolerance of UV-induced DNA damage. The Rad18 protein is a member of the SMC (structural maintenance of chromosomes) superfamily, and we show that, like the other SMC proteins in condensin and cohesin, Rad18 is a component of a high-molecular-weight complex. This complex contains at least six other proteins, the largest of which is Spr18, a novel SMC family member closely related to Rad18, and likely to be its heterodimeric partner. SMC proteins have ATP-binding domains at the N- and C-termini, and two extended coiled-coil domains separated by a hinge in the middle. We show that the N-terminal ATP-binding domain of Rad18 is essential for all functions, and overexpression of an N-terminal mutant has a dominant-negative effect. We have identified an important mutation (S1045A) near the C-terminus of Rad18 that separates its repair and essential roles. Potential models for the role of the Rad18-Spr18 complex during DNA repair are discussed.
authors.affiliation: MRC Cell Mutation Unit, University of Sussex, Falmer, Brighton BN1 9RR, UK.
authors.forename: M I
authors.initials: MI
authors.lastname: Fousteri
authors.forename: A R
authors.initials: AR
authors.lastname: Lehmann
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D005800:Genes, Fungal; D005816:Genetic Complementation Test; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D008970:Molecular Weight; D016297:Mutagenesis, Site-Directed; D010641:Phenotype; D029701:Saccharomyces cerevisiae Proteins; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins; D017386:Sequence Homology, Amino Acid
chemical_list: D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D046911:Macromolecular Substances; C063607:RAD18 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D029702:Schizosaccharomyces pombe Proteins; C486628:Smc5 protein, S pombe; D000251:Adenosine Triphosphatases