title: Yeast origin recognition complex is involved in DNA replication and transcriptional silencing.
abstract: The HMR E silencer represses transcription of silent mating-type genes in the budding yeast Saccharomyces cerevisiae and contains three redundant regulatory elements A, E and B (ref. 1). The A element contains the 11 base pair consensus sequence that is essential for the firing of DNA replication origins. A multisubunit protein called the origin recognition complex (ORC) binds specifically to this consensus sequence within yeast origins in vitro and in vivo. We isolated mutants in A element-mediated silencing and report here that one of the genes we identified, RRR1, encodes ORC2, the 72K subunit of ORC. RRR1/ORC2 is an essential gene, but the rrr1-316 allele, which is viable, is defective in the replication of nuclear DNA and the maintenance of the 2-microns episomal DNA. This is, to our knowledge, the first genetic evidence that ORC is involved in DNA replication and silencing.
authors.affiliation: MRC Laboratory of Molecular Biology, Cambridge, UK.
authors.forename: G
authors.initials: G
authors.lastname: Micklem
authors.forename: A
authors.initials: A
authors.lastname: Rowley
authors.forename: J
authors.initials: J
authors.lastname: Harwood
authors.forename: K
authors.initials: K
authors.lastname: Nasmyth
authors.forename: J F
authors.initials: JF
authors.lastname: Diffley
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D004261:DNA Replication / Q000502:physiology*; D004271:DNA, Fungal / Q000235:genetics*; D004268:DNA-Binding Proteins; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology*; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D009154:Mutation; D051738:Origin Recognition Complex; D012045:Regulatory Sequences, Nucleic Acid / Q000502:physiology; D012097:Repressor Proteins / Q000235:genetics / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C497215:ORC2 protein, S cerevisiae; D051738:Origin Recognition Complex; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins