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 plasmids. In one of these strains, designated Wat, at least 12 distinct plasmid-like elements were identified. From molecular analyses a minimum number of 78 individual linear molecules with proteins bound to their 5' ends was estimated. In addition, the different members of this family of typical linear plasmids were shown to possess a common central region and terminal sequences which differ from one plasmid to another due to the presence of different numbers of a 2.4 kb sequence module. Finally, the pWa6 plasmids share a high degree of sequence similarity with pAL2-1, a linear plasmid previously identified in mitochondria of a long-lived mutant of P.anserina. A mechanism is proposed which explains the generation of these distinct, closely related extra-chromosomal genetic traits.