Testing the occurrence of forward hyper-translocation during the promoter escape transition
Abstract
The macromolecular process of RNA transcription is composed of three
phases, initiation, elongation and termination. At many promoters, RNA
polymerase (RNAP) repetitively aborts short RNAs 2 to 15 nucleotides (nts) in
length before successfully making the transition to the elongation phase.
Mutations in the initial transcribed sequence (ITS) region, from +3 to +10, of
Eσ70-dependent T5 N25 promoter lengthen the abortive initiation program, and
lead to the formation of the very long abortive transcripts (VLATs) of 16 to 21
nts. Recent published work done in the lab suggests that the VLATs formation
may result from forward hyper-translocation movement of RNAP during the
escape transition. This project is aimed to test the physical occurrence of forward
hyper-transcription by binding a non-cleaving E111Q EcoRI protein roadblock to
stall the forward translocating RNAP and thus prevent the formation of VLATs.