9FJS

Cryo-EM structure of Mycobacterium tuberculosis sigma-B RNA polymerase bound to -10 promoter element ssDNA oligo - sigma-B undocked conformation

Summary for 9FJS

• Entry DOI: 10.2210/pdb9fjs/pdb
• EMDB information: 50511
• Descriptor: DNA-directed RNA polymerase subunit alpha, DNA-directed RNA polymerase subunit beta, DNA-directed RNA polymerase subunit beta', ... (8 entities in total)
• Functional Keywords: rna polymerase; sigma factor; sigb, stress response; -10 promoter element; promoter recognition; tuberculosis, transcription
• Biological source: Mycobacterium tuberculosis H37Rv; More
• Total number of polymer chains: 7
• Total formula weight: 408407.82

Authors

Brodolin, K.,Blaise, M. (deposition date: 2024-05-31, release date: 2025-04-02, Last modification date: 2025-05-07)

Primary citation

Vishwakarma, R.K.,Marechal, N.,Morichaud, Z.,Blaise, M.,Margeat, E.,Brodolin, K.
Single-stranded DNA drives sigma subunit loading onto mycobacterial RNA polymerase to unlock initiation-competent conformations.
Nucleic Acids Res., 53:-, 2025

PubMed Abstract: Initiation of transcription requires the formation of the "open" promoter complex (RPo). For this, the σ subunit of bacterial RNA polymerase (RNAP) binds to the nontemplate strand of the -10 element sequence of promoters and nucleates DNA unwinding. This is accompanied by a cascade of conformational changes on RNAP, the exact mechanics of which remains elusive. Here, using single-molecule Förster resonance energy transfer and cryo-electron microscopy, we explored the conformational landscape of RNAP from the human pathogen Mycobacterium tuberculosis upon binding to a single-stranded DNA (ssDNA) fragment that includes the -10 element sequence (-10 ssDNA). We found that like the transcription activator RNAP-binding protein A, -10 ssDNA induced σ subunit loading onto the DNA/RNA channels of RNAP. This triggered RNAP clamp closure and unswiveling that are required for RPo formation and RNA synthesis initiation. Our results reveal a mechanism of ssDNA-guided RNAP maturation and identify the σ subunit as a regulator of RNAP conformational dynamics.

PubMed: 40240004
DOI: 10.1093/nar/gkaf272

Experimental method

ELECTRON MICROSCOPY (3.48 Å)