PLUS STRAND STRONG-STOP DNA TRANSFER IN YEAST TY RETROTRANSPOSONS

The yeast Ty1 LTR retrotransposon replicates by reverse transcription and integration; the process shows many similarities to the retroviral life cycle, However, we show that plus strand strong-stop DNA transfe r in yeast Ty1 elements differs from the analogous retroviral process, By analysis of the native structure of the Ty1 primer binding site an d by a series of manipulations of this region and assessment of the ef fects on retrotransposition, we show that primer binding site inherita nce is not from the tRNA primer, which is inconsistent with classical retroviral models, This unusual inheritance pattern holds even when th e Ty1 primer binding site is lengthened in order to be more retrovirus -like. Finally, the distantly related Ty3 element has an inheritance p attern like Ty1, indicating evolutionary conservation of the alternati ve pathway used by Ty1. Based on these results we arrive at a plus str and primer recycling model that explains Ty1 plus strand strong-stop D NA transfer and inheritance patterns in the primer binding site.