8hkc

From Proteopedia

Cryo-EM structure of E. coli RNAP sigma32 complex

Structural highlights

8hkc is a 7 chain structure with sequence from Escherichia coli and Escherichia coli K-12. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	Electron Microscopy, Resolution 2.49Å
Ligands:	,
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

RPOA_ECOLI DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates. This subunit plays an important role in subunit assembly since its dimerization is the first step in the sequential assembly of subunits to form the holoenzyme.[HAMAP-Rule:MF_00059]

Publication Abstract from PubMed

Bacterial RNA polymerases (RNAP) form distinct holoenzymes with different sigma factors to initiate diverse gene expression programs. In this study, we report a cryo-EM structure at 2.49 A of RNA polymerase transcription complex containing a temperature-sensitive bacterial sigma factor, sigma(32) (sigma(32)-RPo). The structure of sigma(32)-RPo reveals key interactions essential for the assembly of E. coli sigma(32)-RNAP holoenzyme and for promoter recognition and unwinding by sigma(32). Specifically, a weak interaction between sigma(32) and -35/-10 spacer is mediated by T128 and K130 in sigma(32). A histidine in sigma(32), rather than a tryptophan in sigma(70), 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 betaFTH and sigma(4) from other sigma-engaged RNAPs and biochemical data suggest that a biased sigma(4)-betaFTH 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 sigma factors.

Structural Insight into the Mechanism of sigma32-Mediated Transcription Initiation of Bacterial RNA Polymerase.,Lu Q, Chen T, Wang J, Wang F, Ye W, Ma L, Wu S Biomolecules. 2023 Apr 25;13(5):738. doi: 10.3390/biom13050738. PMID:37238608^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Lu Q, Chen T, Wang J, Wang F, Ye W, Ma L, Wu S. Structural Insight into the Mechanism of σ32-Mediated Transcription Initiation of Bacterial RNA Polymerase. Biomolecules. 2023 Apr 25;13(5):738. PMID:37238608 doi:10.3390/biom13050738