Properties of REP3: a cis-acting locus required for stable propagation of the Saccharomyces cerevisiae plasmid 2 microns circle.
Stable propagation of the yeast plasmid 2 microns requires an origin of replication, a cis-active locus designated REP3, and two plasmid-encoded proteins which are the products of the REP1 and REP2 genes. The three REP loci appear to constitute a partitioning system, ensuring equal distribution of plasmid molecules to mother and daughter cells after mitosis. We have localized the REP3 site completely within a segment of five-and-one-half direct tandem repeats of a 62-base-pair unit, bordered by HpaI and AvaI restriction sites within the large unique region of the 2 microns genome. In addition, we find that the repeated elements are functionally distinct. Only a subset of the repeats is necessary to promote full partitioning activity. The other repeats appear to promote plasmid transcription. These results are discussed in the context of a model of plasmid copy control involving titration of a plasmid-specific protein by the repeated elements within REP3.
D001483:Base Sequence; D004261:DNA Replication; D004270:DNA, Circular / Q000096:biosynthesis; D004926:Escherichia coli / Q000235:genetics; D005800:Genes, Fungal; D005809:Genes, Regulator; D010957:Plasmids; D011401:Promoter Regions, Genetic; D012093:Replicon; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D014170:Transformation, Genetic
D004270:DNA, Circular