title: Chromosomal ARS1 has a single leading strand start site.
abstract: Initiation sites for DNA synthesis in the chromosomal autonomously replicating sequence (ARS)1 of Saccharomyces cerevisiae were detected at the nucleotide level. The transition from discontinuous to continuous synthesis defines the origin of bidirectional replication (OBR), which mapped adjacent to the origin recognition complex binding site. To ascertain which sites represented starts for leading or lagging strands, we characterized DNA replication from ARS1 in a cdc9 (DNA ligase I) mutant, defective for joining Okazaki fragments. Leading strand synthesis in ARS1 initiated at only a single site, the OBR. Thus, replication in S. cerevisiae is not initiated stochastically by choosing one out of multiple possible sites but, rather, is a highly regulated process with one precise start point.
authors.affiliation: Division of Biology and Medicine, Brown University, Providence, Rhode Island 02912, USA.
authors.forename: A K
authors.initials: AK
authors.lastname: Bielinsky
authors.forename: S A
authors.initials: SA
authors.lastname: Gerbi
mesh_terms: D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002874:Chromosome Mapping; D002875:Chromosomes / Q000235:genetics; D004247:DNA / Q000235:genetics; D000072481:DNA Ligase ATP; D011088:DNA Ligases / Q000235:genetics; D004261:DNA Replication / Q000235:genetics*; D005800:Genes, Fungal / Q000235:genetics*; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D010957:Plasmids / Q000235:genetics; D018741:Replication Origin / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics*
chemical_list: C000607890:CDC9 protein, S cerevisiae; C022262:Okazaki fragments; D004247:DNA; D011088:DNA Ligases; D000072481:DNA Ligase ATP