8HKC

Cryo-EM structure of E. coli RNAP sigma32 complex

Summary for 8HKC

• Entry DOI: 10.2210/pdb8hkc/pdb
• EMDB information: 34849
• 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: transcription, rna polymerase, sigma factor, heat shock response, transcription-dna complex, transcription/dna
• Biological source: Escherichia coli K-12; More
• Total number of polymer chains: 7
• Total formula weight: 448503.79

Authors

Wu, S.,Ma, L.X. (deposition date: 2022-11-25, release date: 2023-05-31, Last modification date: 2024-07-03)

Primary citation

Lu, Q.,Chen, T.,Wang, J.,Wang, F.,Ye, W.,Ma, L.,Wu, S.
Structural Insight into the Mechanism of sigma 32-Mediated Transcription Initiation of Bacterial RNA Polymerase.
Biomolecules, 13:-, 2023

PubMed Abstract: Bacterial RNA polymerases (RNAP) form distinct holoenzymes with different σ factors to initiate diverse gene expression programs. In this study, we report a cryo-EM structure at 2.49 Å of RNA polymerase transcription complex containing a temperature-sensitive bacterial σ factor, σ (σ-RPo). The structure of σ-RPo reveals key interactions essential for the assembly of σ-RNAP holoenzyme and for promoter recognition and unwinding by σ. Specifically, a weak interaction between σ and -35/-10 spacer is mediated by T128 and K130 in σ. A histidine in σ, rather than a tryptophan in σ, acts as a wedge to separate the base pair at the upstream junction of the transcription bubble, highlighting the differential promoter-melting capability of different residue combinations. Structure superimposition revealed relatively different orientations between βFTH and σ from other σ-engaged RNAPs and biochemical data suggest that a biased σ-βFTH configuration may be adopted to modulate binding affinity to promoter so as to orchestrate the recognition and regulation of different promoters. Collectively, these unique structural features advance our understanding of the mechanism of transcription initiation mediated by different σ factors.

PubMed: 37238608
DOI: 10.3390/biom13050738

Experimental method

ELECTRON MICROSCOPY (2.49 Å)