Interaction of tRNA transcription factors with satellite I DNA from Xenopus laevis.

A cloned repeat of Xenopus laevis satellite I DNA was tested for the ability to form stable complexes with tRNA transcription factors in vitro. In template exclusion studies, the satellite I DNA competed efficiently with a tRNA gene for binding of yeast RNA polymerase III transcription factors. DNase I footprinting further showed that transcription factor TF IIIC alone bound to satellite I DNA at both the A block and B block consensus promoter sequences immediately downstream from the transcription start point. The strength and position of these associations indicate that satellite I DNA is a potential site for association of the same DNA-binding proteins that activate tRNA gene transcription.