Biologjia Online

Weakening of the T7 promoter:Polymerase interaction facilitates promoter

During transcription initiation RNA polymerases retain interactions with their promoters until the RNA is extended to 8-13 nts, at which point the polymerase releases the promoter and moves downstream. It has been shown that release of the T7 promoter is inhibited if the T7 RNA polymerase:promoter interaction is strengthened. Here we ask if release will be facilitated if the T7 promoter:polymerase interaction is weakened by the introduction of promoter mutations known to reduce promoter activity. Using chemical and enzymatic probes to monitor the position of the polymerase as a function of RNA length we find that promoter mutations upstream of -4 facilitate release of the polymerase from the promoter, but more downstream mutations do not have such effects. We also find that released complexes turn over more slowly than promoter bound complexes, indicating that retention of promoter interactions contributes to the dissociation of short RNAs during initial transcription.

posted by Selfmaderadio @ 4:46 e pasdites