Structural Insights into De Novo Promoter Escape by Mycobacterium tuberculosis RNA Polymerase

Transcription in bacteria is a multi-step process. In the first step, contacts between RNA polymerase and the promoter DNA must be established for transcription initiation to begin, but then these contacts must be broken for the enzyme to transition into the elongation phase. Single-molecule and biochemical observations report that promoter escape is a highly regulated and sometimes rate-limiting step in the transcription cycle; however, the structural mechanisms of promoter escape remain obscure. Promoter escape also serves as the target for the clinically important antibiotic rifampicin, used to treat tuberculosis. Here, we present seven distinct intermediates showing the structural details of M. tuberculosis RNA polymerase initial transcribing complexes and promoter escape, using a de novo cryo-electron microscopy approach. We describe the structural rearrangements that RNA polymerase undergoes to clear the promoter, including those required to release the initiation factor, σ, providing a structural account for decades of biochemical observations. These structures and supporting biochemistry provide a model of promoter escape, a universal step in the transcription cycle, with conformations that may be used to develop Rifampicin alternatives. Promoter escape is a key step in bacterial transcription and a target of the antibiotic rifampicin. Here, the authors use cryo-EM to explore this step, finding seven structural intermediates of M. tuberculosis RNA polymerase during promoter escape.

• Publication year

  2025

• Venue

  Nature Communications

• Publication date

  2025-11-13

• Fields of study

  Biology, Medicine

• Identifiers
  DOI 10.1038/s41467-025-64941-7PMID 41233305PMCID 12615793
• External record

  Open on Semantic Scholar

• Source metadata

  Semantic Scholar, PubMed

• No claims are published for this paper.

• No concepts are published for this paper.

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