2-micrometers DNA-like plasmids in the osmophilic haploid yeast Saccharomyces rouxii
2-micrometers DNA-like plasmids in the osmophilic haploid yeast Saccharomyces rouxii
复制标题
嗜压单倍体酵母 Saccharomyces rouxii 中的 2 微米 DNA 样质粒
作者：
A. Toh;S. Tada;Y. Oshima
在100株非酿酒酵母菌中，有2株鲁氏酵母菌检出DNA质粒。质粒pSR 1和pSR 2与2微米的S.啤酒。pSR 1和pSR 2用限制性内切酶BamHI、EcoRI、HincII、HindIII和XhoI得到相同的限制性图谱，并且都缺少Pst I、SalI和SmaI的限制性位点。然而，这些地图与S.酿酒酵母2微米DNA。限制性酶切分析也揭示了两种异构形式的每个质粒，并建议存在一对反向重复序列的分子内发生重组。pSR 1和pSR 2 DNA之间的DNA-DNA杂交表明它们的碱基序列之间有显著的同源性，而pSR 1和pJDB 219之间没有检测到同源性，pJDB 219是由2微米DNA的整个分子、质粒pMB 9和S.携带LEU 2基因的酿酒酵母。用pSR 1和YIp 1构建的嵌合质粒，将pBR 322的较大EcoR Ⅰ-SalI片段与S.酿酒酵母中携带有HIS 3基因，能在酵母中自主复制。酿酒酵母宿主和产生的异构体，大概是通过分子内重组在反向重复。
DNA plasmids were detected in two independent strains of Saccharomyces rouxii among 100 yeast strains other than Saccharomyces cerevisiae tested. The plasmids, pSR1 and pSR2, had almost the same mass (approximately 4 X 10(6) daltons) as 2-micrometers DNA of S. cerevisiae. pSR1 and pSR2 gave identical restriction maps with restriction endonucleases BamHI, EcoRI, HincII, HindIII, and XhoI, and both lacked restriction sites for PstI, SalI, and SmaI. These maps, however, differed significantly from that of S. cerevisiae 2-micrometers DNA. Restriction analysis also revealed two isomeric forms of each plasmid and suggested the presence of a pair of inverted repeat sequences in the molecules where intramolecular recombination took place. DNA-DNA hybridization between the pSR1 and pSR2 DNAs indicated significant homology between their base sequences, whereas no homology was detected between pSR1 and pJDB219, a chimeric plasmid constructed from a whole molecule of 2-micrometers DNA, plasmid pMB9, and a 1.2-kilobase DNA fragment of S. cerevisiae bearing the LEU2 gene. A chimeric plasmid constructed with pSR1 and YIp1, the larger EcoRI-SalI fragment of pBR322 ligated with a 6.1-kilobase DNA fragment of S. cerevisiae bearing the HIS3 gene, could replicate autonomously in an S. cerevisiae host and produced isomers, presumably by intramolecular recombination at the inverted repeats.