Visualization of two architectures in class-II CAP-dependent transcription activation

• DOI: 10.1371/journal.pbio.3000706
• Publication Date: 2020-04-20T17:31:56Z
• Authors: Wei Shi; Yanan Jiang; Yibin Deng; Zigang Dong; Bin Liu
• Keywords: Transcription; RNA polymerase II; General transcription factor; Transcription preinitiation complex

Transcription activation by cyclic AMP (cAMP) receptor protein (CAP) is the classic paradigm of transcription regulation in bacteria. CAP was suggested to activate on class-II promoters via a recruitment and isomerization mechanism. However, whether how it modifies RNA polymerase (RNAP) initiate remains unclear. Here, we report cryo–electron microscopy (cryo-EM) structures an intact Escherichia coli CAP-dependent complex (CAP-TAC) with without de novo transcript. The reveal two distinct architectures TAC raise possibility that binding may induce substantial conformational changes all subunits RNAP transiently widen main cleft facilitate DNA promoter entering formation initiation open complex. These structural vanish during further transcript synthesis. observations this study possible on-pathway intermediate suggest activates inducing state, addition previously proposed stabilization