Rayko E, Goursot R
Laboratoire de Génétique Moléculaire, Institut Jacques Monod, Paris, France.
Curr Genet. 1985;10(3):171-7. doi: 10.1007/BF00798746.
We have studied a pleiotropic mutation petD in S. cerevisiae which both confers the inability to grow on glycerol (Gly-) and greatly increases the frequency of cytoplasmic petites (Het). The first phenotype, Gly-, is recessive, whereas the second, Het, is dominant. Genetic and biochemical analysis showed that the majority of the petites in petD strains are not of the rho degree type (completely lacking mit-DNA), but of the rho- type (containing partially deleted mit-DNA). This finding and the fact that the phenotype Het is dominant argue in favour of the involvement of the petD product in the excision process of the mit-DNA. Another nuclear mutation, mod, was shown to exhibit a dominant epistasy with respect to the Het phenotype of the mutation petD. Two types of Gly+ revertants from petD mutants were isolated: rpa revertants, which restore completely the wild-type phenotype, and rpb revertants, which restore only the growth on glycerol, but still allow the production of high frequencies of cytoplasmic petites. Thus the mutations mod and rpb permit the genetic uncoupling of two phenotypes induced by the mutation petD.
我们研究了酿酒酵母中的一个多效性突变petD，它既导致细胞无法在甘油上生长（Gly-），又极大地增加了细胞质小菌落（Het）的出现频率。第一种表型Gly-是隐性的，而第二种表型Het是显性的。遗传和生化分析表明，petD菌株中的大多数小菌落不是rho度型（完全缺乏线粒体DNA），而是rho-型（含有部分缺失的线粒体DNA）。这一发现以及Het表型为显性这一事实表明，petD产物参与了线粒体DNA的切除过程。另一个核突变mod被证明对petD突变的Het表型表现出显性上位性。从petD突变体中分离出两种类型的Gly+回复体：rpa回复体，它完全恢复野生型表型；rpb回复体，它只恢复在甘油上的生长，但仍允许产生高频率的细胞质小菌落。因此，突变mod和rpb使得由petD突变诱导的两种表型在遗传上解偶联。
