A NOVEL FAMILY OF LINEAR PLASMIDS WITH HOMOLOGY TO PLASMID PAL2-1 OF PODOSPORA-ANSERINA

Three recently isolated wild-type strains of the ascomycete Podospora anserina were analyzed for the presence of linear mitochondrial plasmi ds. In one of these strains, designated Wa6, at least 12 distinct plas mid-like elements were identified. From molecular analyses a minimum n umber of 78 individual linear molecules with proteins bound to their 5 ' ends was estimated. In addition, the different members of this famil y of typical linear plasmids were shown to possess a common central re gion and terminal sequences which differ from one plasmid to another d ue to the presence of different numbers of a 2.4 kb sequence module. F inally, the pWa6 plasmids share a high degree of sequence similarity w ith pAL2-1, a linear plasmid previously identified in mitochondria of a long-lived mutant of P.anserina. A mechanism is proposed which expla ins the generation of these distinct, closely related extrachromosomal genetic traits.