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Mechanisms of σ54-Dependent Transcription Initiation and Regulation

Danson, Amy E., Jovanovic, Milija, Buck, Martin, Zhang, Xiaodong
Journal of molecular biology 2019
DNA, DNA-directed RNA polymerase, X-ray diffraction, adenosinetriphosphatase, bacteria, cryo-electron microscopy, environmental factors, humans, sigma factors, stress response, transcription initiation
Cellular RNA polymerase is a multi-subunit macromolecular assembly responsible for gene transcription, a highly regulated process conserved from bacteria to humans. In bacteria, sigma factors are employed to mediate gene-specific expression in response to a variety of environmental conditions. The major variant σ factor, σ54, has a specific role in stress responses. Unlike σ70-dependent transcription, which often can spontaneously proceed to initiation, σ54-dependent transcription requires an additional ATPase protein for activation. As a result, structures of a number of distinct functional states during the dynamic process of transcription initiation have been captured using the σ54 system with both x-ray crystallography and cryo electron microscopy, furthering our understanding of σ54-dependent transcription initiation and DNA opening. Comparisons with σ70 and eukaryotic polymerases reveal unique and common features during transcription initiation.