A single-stranded promoter for RNA polymerase III

AUTOR(ES)
FONTE

The National Academy of Sciences

RESUMO

Single strands of DNA serve, in rare instances, as promoters for transcription; duplex DNA promoters with individual strands that also have a promoter capacity/function have not been described. We show that the nontranscribed strand of the Saccharomyces cerevisiae U6 snRNA gene directs transcription initiation factor IIIB-requiring and accurately initiating transcription by RNA polymerase III. The nontranscribed strand promoter is much more extended than its duplex DNA counterpart, comprising the U6 gene TATA box, a downstream T7 tract, and an upstream-lying segment. A requirement for placement of the 3′ end of the transcribed (template) strand within the confines of the transcription bubble is seen as indicating that the nontranscribed strand provides a scaffold for RNA polymerase recruitment but is deficient at a subsequent step of transcription initiation factor IIIB's direct involvement in promoter opening.

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