Yeti - a degenerate gypsy-like LTR retrotransposon in the filamentous ascomycete Podospora anserina

In the filamentous ascomycete Podospora anserina a 6,935-bp retrotransposon , Yeti, has been identified and characterized. It is flanked by a 5-bp targ et site duplication and contains long terminal repeats (LTRs) 354 bp in len gth. The LTRs show a high degree: of identity to the previously reported re petitive element repa, a sequence suggested to represent a solo-LTR element of an unknown transposon. In the investigated Podospora strains, the numbe r of complete Yeti copies is significantly lower than the number of repa el ements, with up to 25 copies. Yeti appears to be inactive: it is highly deg enerate and no transcripts of the element have been detected even in Podosp ora cultures grown under elevated stress conditions. The amino acid sequenc es deduced from Yeti display significant homology, particularly in the reve rse transcriptase region, to those of other fungal retrotransposons, indica ting that it is a member of the gypsy family. As suggested by the unusual d inucleotide content, degeneration of Yeti appears to be the result of a mol ecular mechanism resembling repeat-induced point mutation in Neurospora cra ssa.