Kiss G B, Amin A A, Pearlman R E
Department of Biology, York University, Downsview, Ontario, Canada.
Mol Cell Biol. 1981 Jun;1(6):535-43. doi: 10.1128/mcb.1.6.535-543.1981.
Plasmids containing the nontranscribed central and terminal, but not the coding, regions of the extrachromosomal ribosomal deoxyribonucleic acid (rDNA) of Tetrahymena thermophila are capable of autonomous replication in Saccharomyces cerevisiae. These plasmids transform S. cerevisiae at high frequency; transformants are unstable in the absence of selection, and plasmids identical to those used for transformation were isolated from the transformed yeast cells. One plasmid contains a 1.85-kilobase Tetrahymena DNA fragment which includes the origin of bidirectional replication of the extrachromosomal rDNA. The other region of Tetrahymena rDNA allowing autonomous replication of plasmids in S. cerevisiae is a 650-base pair, adenine plus thymine-rich segment from the rDNA terminus. Neither of these Tetrahymena fragments shares obvious sequence homology with the origin of replication of the S. cerevisiae 2-microns circle plasmid or with ars1, an S. cerevisiae chromosomal replicator.
含有嗜热四膜虫染色体外核糖体脱氧核糖核酸（rDNA）的非转录中央区和末端区而非编码区的质粒，能够在酿酒酵母中自主复制。这些质粒能高频转化酿酒酵母；在无选择条件下转化子不稳定，并且从转化的酵母细胞中分离出了与用于转化的质粒相同的质粒。一种质粒含有一个1.85千碱基的四膜虫DNA片段，该片段包括染色体外rDNA的双向复制起点。四膜虫rDNA中允许质粒在酿酒酵母中自主复制的另一个区域是来自rDNA末端的一个650碱基对、富含腺嘌呤加胸腺嘧啶的片段。这两个四膜虫片段与酿酒酵母2微米环状质粒的复制起点或与酿酒酵母染色体复制子ars1均无明显的序列同源性。
