Transcription initiation occurs in a several-step mechanism, whereby RNA polymerase (RNAP) recognizes and binds to DNA and forms an opened RNAP-promoter complex (RPo). We aimed at determining which of the interactions occurring between RNAP and DNA promoter affected RPo complex formation the most. DS4 and DS5 variants were studied. They differed in length by two base pairs of a phage promoter ?PR (DS4 and DS5: 8 base pairs; ?PR: 6 base pairs), and varied in sequence from each other at one base pair position. To determine if such discriminator variations cause any effect on RPo stability, various filter binding dissociations were performed at different temperatures and a permanganate footprinting reaction was performed for both variants. Through these experiments it was seen that the change between ?PR and DS4 only affected the lifetime of open complex, while the variations in DS5 also caused large and surprising effect on the system's thermodynamics.

Single base changes in DNA discriminator show large effects on transcription initiation thermodynamics

245th National Meeting (2013)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.