6jnx
From Proteopedia
Cryo-EM structure of a Q-engaged arrested complex
Structural highlights
Function[RPOC_ECOLI] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates.[HAMAP-Rule:MF_01322] [RPOB_ECOLI] DNA-dependent RNA polymerase catalyzes the transcription of DNA into RNA using the four ribonucleoside triphosphates as substrates.[HAMAP-Rule:MF_01321] [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] [RPOZ_ECOLI] Promotes RNA polymerase assembly. Latches the N- and C-terminal regions of the beta' subunit thereby facilitating its interaction with the beta and alpha subunits.[HAMAP-Rule:MF_00366] [RPOD_ECOLI] Sigma factors are initiation factors that promote the attachment of RNA polymerase to specific initiation sites and are then released. This is the primary sigma factor of this bacterium. Publication Abstract from PubMedBacteriophage Q protein engages sigma-dependent paused RNA polymerase (RNAP) by binding to a DNA site embedded in late gene promoter and renders RNAP resistant to termination signals. Here, we report a single-particle cryo-electron microscopy (cryo-EM) structure of an intact Q-engaged arrested complex. The structure reveals key interactions responsible for sigma-dependent pause, Q engagement, and Q-mediated transcription antitermination. The structure shows that two Q protomers (Q(I) and Q(II)) bind to a direct-repeat DNA site and contact distinct elements of the RNA exit channel. Notably, Q(I) forms a narrow ring inside the RNA exit channel and renders RNAP resistant to termination signals by prohibiting RNA hairpin formation in the RNA exit channel. Because the RNA exit channel is conserved among all multisubunit RNAPs, it is likely to serve as an important contact site for regulators that modify the elongation properties of RNAP in other organisms, as well. Structural basis of Q-dependent transcription antitermination.,Shi J, Gao X, Tian T, Yu Z, Gao B, Wen A, You L, Chang S, Zhang X, Zhang Y, Feng Y Nat Commun. 2019 Jul 2;10(1):2925. doi: 10.1038/s41467-019-10958-8. PMID:31266960[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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