title: Identification of two origins of replication in the single chromosome of the archaeon Sulfolobus solfataricus.
abstract: Eukaryotic chromosomes possess multiple origins of replication, whereas bacterial chromosomes are replicated from a single origin. The archaeon Pyrococcus abyssi also appears to have a single origin, suggesting a common rule for prokaryotes. However, in the current work, we describe the identification of two active origins of replication in the single chromosome of the hyperthermophilic archaeon Sulfolobus solfataricus. Further, we identify conserved sequence motifs within the origins that are recognized by a family of three Sulfolobus proteins that are homologous to the eukaryotic initiator proteins Orc1 and Cdc6. We demonstrate that the two origins are recognized by distinct subsets of these Orc1/Cdc6 homologs. These data, in conjunction with an analysis of the levels of the three Orc1/Cdc6 proteins in different growth phases and cell cycle stages, lead us to propose a model for the roles for these proteins in modulating origin activity.
authors.affiliation: Medical Research Council Cancer Cell Unit, Hutchison MRC Research Centre, Hills Road, Cambridge CB2 2XZ, United Kingdom.
authors.forename: Nicholas P
authors.initials: NP
authors.lastname: Robinson
authors.forename: Isabelle
authors.initials: I
authors.lastname: Dionne
authors.forename: Magnus
authors.initials: M
authors.lastname: Lundgren
authors.forename: Victoria L
authors.initials: VL
authors.lastname: Marsh
authors.forename: Rolf
authors.initials: R
authors.lastname: Bernander
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Bell
mesh_terms: D019843:Archaeal Proteins / Q000235:genetics / Q000302:isolation & purification*; D001665:Binding Sites / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics / Q000302:isolation & purification; D002874:Chromosome Mapping; D019847:Chromosomes, Archaeal / Q000235:genetics*; D004261:DNA Replication / Q000235:genetics*; D018076:DNA, Complementary / Q000032:analysis / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000302:isolation & purification; D019143:Evolution, Molecular; D008969:Molecular Sequence Data; D051738:Origin Recognition Complex; D011485:Protein Binding / Q000235:genetics; D018741:Replication Origin / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid; D016944:Sulfolobus / Q000235:genetics*
chemical_list: D019843:Archaeal Proteins; C066503:CDC6 protein, S cerevisiae; D018797:Cell Cycle Proteins; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D051738:Origin Recognition Complex; D029701:Saccharomyces cerevisiae Proteins