Separable functions of ORC5 in replication initiation and silencing in Saccharomyces cerevisiae.
Origin recognition complex (ORC) is a six subunit complex that functions as the replication initiator and is required for silencing the HML and HMR loci in the yeast Saccharomyces cerevisiae. The roles of ORC5 in replication initiation and silencing were investigated to determine whether the two roles were mechanistically coincident or separable. Some spontaneous revertants of orc5-1 were functional for replication initiation, but not silencing. Other alleles of ORC5 were obtained that were nonfunctional for replication initiation, but fully competent for silencing. The two types of alleles, when put in the same cell, complemented, establishing two separable functions for ORC5. These data implied that replication initiation at HMR-E was not required for silencing. The data were consistent with a model in which different ORC species functioned at different origins within the genome and that only one Orc5p subunit functioned at any given origin.
Dillin
A
A
Department of Molecular and Cell Biology, University of California, Berkeley 94720, USA.
Rine
J
J
D000483:Alleles; D018797:Cell Cycle Proteins / Q000235:genetics / Q000502:physiology*; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology*; D005816:Genetic Complementation Test; D051738:Origin Recognition Complex; D018741:Replication Origin; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D014158:Transcription, Genetic
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; C497220:ORC5 protein, S cerevisiae; C109973:ORC5 protein, mouse; D051738:Origin Recognition Complex; D029701:Saccharomyces cerevisiae Proteins