Foury F, Kolodynski J
Proc Natl Acad Sci U S A. 1983 Sep;80(17):5345-9. doi: 10.1073/pnas.80.17.5345.
Three allelic nuclear mutants affected in the recombination of mtDNA have been characterized in Saccharomyces cerevisiae and assigned to the PIF locus. In the mutants, the general recombination measured by the recombination frequency between linked or unlinked alleles is normal. However, the pif mutations prevent the integration into the rho+ genome of the markers (oli1, oli2, diu1, ery, oxi1, oxi2) of those rho- genomes that have tandemly arrayed repeat units. Therefore, these rho- genomes characterize a PIF-dependent recombination system. The pif mutations have also revealed the existence of a PIF-independent recombination system used by those rho- genomes that have an inverted organization of their repeat units. The markers of such palindromic rho- genomes exhibit high integration frequency into the rho+ genome even in the presence of the pif mutation. In addition, the pif mutations greatly increase suppressiveness in crosses between pif rho+ strains and PIF-dependent as well as PIF-independent rho- clones. We conclude that the recombination between rho+ and rho- genomes involves at least two distinct systems that depend on the organization of the rho- genome.
在酿酒酵母中已经鉴定出三个影响线粒体DNA（mtDNA）重组的等位核突变体，并将其定位到PIF基因座。在这些突变体中，通过连锁或非连锁等位基因之间的重组频率来衡量的一般重组是正常的。然而，pif突变阻止了那些具有串联重复单位的rho-基因组的标记（oli1、oli2、diu1、ery、oxi1、oxi2）整合到rho+基因组中。因此，这些rho-基因组表征了一个依赖PIF的重组系统。pif突变还揭示了存在一个不依赖PIF的重组系统，该系统被那些重复单位呈反向排列的rho-基因组所使用。即使存在pif突变，这种回文rho-基因组的标记在整合到rho+基因组时仍表现出高频率。此外，pif突变极大地增加了pif rho+菌株与依赖PIF以及不依赖PIF的rho-克隆之间杂交的抑制性。我们得出结论，rho+和rho-基因组之间的重组至少涉及两个不同的系统，这两个系统取决于rho-基因组的组织形式。
