Genetic and physiological characterization of met15 mutants of Saccharomyces cerevisiae: a selective system for forward and reverse mutations.
Genetic and physiological characterization of met15 mutants of Saccharomyces cerevisiae: a selective system for forward and reverse mutations.
复制标题
酿酒酵母met15突变体的遗传和生理特征：正向和反向突变的选择性系统。
作者：
A. Singh;F. Sherman
从温度敏感性、渗透补救性、等位基因间互补、琥珀色和赭色抑制因子的抑制性等方面对酿酒酵母me15基因座的133个自发突变体和诱导突变体进行了表征。40个突变体具有渗透性补救作用；其中17种，没有其他的，也是温度敏感的。133个突变中有7个被琥珀色抑制子抑制，11个被赭色抑制子抑制。70%的突变体表现出等位基因间的互补，这表明met15基因的功能基因产物是一种多聚体蛋白。根据x射线诱导的各种异等位二倍体有丝分裂逆转的频率，估计了30me15的相对图谱位置。所有互补的无义突变都位于基因的一端附近，而其他无义突变则跨越基因的大部分，从而将mRNA的翻译方向与精细结构图联系起来。重组研究表明，30个突变体中有两个包含整个met - 15位点的缺失。——已经确定了多种突变类型，包括错义、无义和缺失，可以通过这个独特的系统恢复，在这个系统中，可以根据met15突变体的甲基汞抗性和蛋氨酸需求选择正向和反向突变。
One hundred and thirty-three spontaneous and induced mutants of the met15 locus in Saccharomyces cerevisiae were characterized with respect to temperature sensitivity, osmotic remediability, interallelic complementation, and suppressibility by amber and ochre suppressors. Forty mutants are osmotic remedial; 17 of these, and no others, are also temperature-sensitive. Seven of 133 mutations are suppressible by an amber suppressor and 11 are suppressible by an ochre suppressor. Seventy percent of the mutants exhibited interallelic complementation, suggesting that the functional gene product of the met15 gene is a multimeric protein. Relative map positions of 30 met15 were estimated from the frequencies of X-ray-induced mitotic reversion of various heteroallelic diploids. All complementing nonsense mutations are located near one end of the gene in contrast to other nonsense mutations which span most of the gene, thus relating the direction of translation of the mRNA with respect to the fine-structure map. Recombination studies indicated that two of 30 mutants contained deletions of the entire met15 locus. -- It was established that a variety of mutational types, including missense, nonsense, and deletions, are recovered with this unique system in which both forward and reverse mutations can be selected on the basis of methyl mercury resistance and methionine requirement of the met15 mutants.