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Publication Abstract from PubMed

Gene transcription is carried out by RNA polymerase (RNAP) and requires the conversion of the initial closed promoter complex, where DNA is double stranded, to a transcription-competent open promoter complex, where DNA is opened up. In bacteria, RNAP relies on sigma factors for its promoter specificities. Using a special form of sigma factor (sigma(54)), which forms a stable closed complex and requires its activator that belongs to the AAA+ ATPases (ATPases associated with diverse cellular activities), we obtained cryo-electron microscopy structures of transcription initiation complexes that reveal a previously unidentified process of DNA melting opening. The sigma(54) amino terminus threads through the locally opened up DNA and then becomes enclosed by the AAA+ hexameric ring in the activator-bound intermediate complex. Our structures suggest how ATP hydrolysis by the AAA+ activator could remove the sigma(54) inhibition while helping to open up DNA, using sigma(54) amino-terminal peptide as a pry bar.

Mechanisms of DNA opening revealed in AAA+ transcription complex structures.,Ye F, Gao F, Liu X, Buck M, Zhang X Sci Adv. 2022 Dec 21;8(51):eadd3479. doi: 10.1126/sciadv.add3479. Epub 2022 Dec , 21. PMID:36542713^[1]

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