Evidence for cis- and trans-acting element coevolution of the 2-microns circle genome in Saccharomyces cerevisiae.
We compared the DNA sequence of the yeast 2-microns plasmid cis-acting STB and transacting REP1 partition loci of laboratory haploid and industrial amphiploid strains. Several industrial strains had a unique STB sequence (type 1) sharing only 70% homology with laboratory STB (type 2). Type 1 plasmids had a REP1 protein with 6-10% amino acid substitutions when compared to REP1 of type 2 plasmids. All 2-microns variants that shared a similar STB consensus sequence exhibited a high degree of REP1 nucleotide and amino acid sequence conservation. These observations suggest molecular coevolution of trans-acting elements with cognate target DNA structure. Based on DNA sequencing and Southern hybridization analyses, we classified 2-microns variants into two main evolutionary lineages that differ at STB as well as REP1 loci. The role of molecular coevolution in yeast intra- and interspecies plasmid evolution was discussed.
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Department of Biology, University of Saskatchewan, Saskatoon, Canada.
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D000595:Amino Acid Sequence; D001483:Base Sequence; D005075:Biological Evolution; D003001:Cloning, Molecular; D004271:DNA, Fungal; D005656:Fungal Proteins / Q000235:genetics*; D005800:Genes, Fungal; D014644:Genetic Variation; D006238:Haploidy; D008969:Molecular Sequence Data; D010802:Phylogeny; D010957:Plasmids; D012150:Polymorphism, Restriction Fragment Length; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid
D004271:DNA, Fungal; D005656:Fungal Proteins; C051237:REP protein, yeast plasmid