Kinetic-mechanistic evidence for which E. coli RNA polymerase-λPR open promoter complex initiates and for stepwise disruption of contacts in bubble collapse

Abstract

To report the kinetics of initial transcription at the λPR promoter at 25 °C and 37 °C. Rapid-quench mixing is used to determine overall rates of full-length RNA synthesis and rate constants for individual nucleotide addition steps at two nucleotide conditions (designated high UTP, low UTP) for comparison with the 19 °C results. These studies address the questions of which OC conformation is capable of binding nucleotides and which specific RNAP-promoter contacts are disrupted in the individual steps of hybrid-translocation, resulting in collapse of the initiation bubble and escape of RNAP from the promoter. In addition, they provide key available under aCC-BY-NC-ND 4.0 International license.(which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made bioRxiv preprint doi: https://doi.org/10.1101/2020.09.11.293670; this version posted September 24, 2020. The copyright holder for this preprint 6 thermodynamic information about the I3 OC and the steps by which the unstable I2 OC converts to RPO.