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Mechanisms of DNA opening revealed in AAA+ transcription complex structures.

ABSTRACT: 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 σ factors for its promoter specificities. Using a special form of sigma factor (σ⁵⁴), 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 σ⁵⁴ 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 σ⁵⁴ inhibition while helping to open up DNA, using σ⁵⁴ amino-terminal peptide as a pry bar.

SUBMITTER: Ye F

PROVIDER: S-EPMC9770992 | biostudies-literature | 2022 Dec

REPOSITORIES: biostudies-literature

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Mechanisms of DNA opening revealed in AAA+ transcription complex structures.

Ye Fuzhou F Gao Forson F Liu Xiaojiao X Buck Martin M Zhang Xiaodong X

Science advances 20221221 51

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 σ factors for its promoter specificities. Using a special form of sigma factor (σ<sup>54</sup>), which forms a stable closed complex and requires its activator that belongs to the AAA+ ATPases (ATPases associated with diverse cellular acti ...[more]

PMID: 36542713

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