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Unformatted text preview: Chapter 13 Bacterial RNAP similar to eukaryotic RNAP and similar RNA polymerase: catalyzes nucleoside monophosphate group transfer from a nucleoside triphosphate to 3 end of growing RNA chain Phosphodiester bond formation: attack of OH- hydroxyl group, pyrophosphate hydrolysis drives reaction to completion DNA sequence determines RNA sequence Grows in 5 3 direction, added to 3 OH end No primer needed Only ribonucleosidetriphosphates participate in synthesis Respond to variety of regulatory proteins that alter polymerase activity to recognize binding site Nontemplate DNA strand: coding strand (same sequence as RNA U=T) Primary transcript: new RNA strand Position +1: nucleotide at transcription start site (after it= downstream, 3 side) (before it=upstream, 5 side) E. Coli- RNA polymerase holoenzyme ( 2 , 70 ) Initiation: 2 (core polymerase) and factor (studies done missing the subunit) Core polymerase: synthesize RNA molecules from 1x stranded & nicked DNA templates, cannot use intact circular 2x stranded DNA Compact DNA harder to bind factor and subunit not required for phosphodiester bond formation DNA unwinds at nicks to give nonphysiological initiation sites Begins when holoenzyme recognizes and binds to specific initiation signals called promoters Promoter mutations: cannot be complemented because they are cis...
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