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Publication Abstract from PubMed

In bacteria, the dissociable sigma subunit of the RNA polymerase (RNAP) is responsible for initiating RNA synthesis from specific DNA sites. As nascent RNA grows, downstream DNA unwinds and is pulled into the RNAP, causing stress accumulation and initiation complex destabilization. Processive transcription elongation requires at least partial separation of the sigma factor from the RNAP core enzyme. Here, we present a series of transcription complexes captured between the early initiation and elongation phases via in-crystal RNA synthesis and cleavage. Crystal structures of these complexes indicate that stress accumulation during transcription initiation is not due to clashing of the growing nascent RNA with the sigma(3.2) loop, but results from scrunching of the template strand DNA that is contained inside the RNAP by the sigma(3) domain. Our results shed light on how scrunching of template-strand DNA drives both abortive initiation and sigma-RNAP core separation to transition transcription from initiation to elongation.

Structural Insights into Transcription Initiation from De Novo RNA Synthesis to Transitioning into Elongation.,Zuo Y, De S, Feng Y, Steitz TA iScience. 2020 Aug 11;23(9):101445. doi: 10.1016/j.isci.2020.101445. eCollection , 2020 Sep 25. PMID:32829286^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.