Cryo-EM structure of Escherichia coli σ 70 RNA polymerase and promoter DNA complex revealed a role of σ non-conserved region during the open complex formation.

Autor: Narayanan A; Department of Biochemistry and Molecular Biology, The Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802; Department of Biological Sciences, Markey Center for Structural Biology, Purdue University, West Lafayette, Indiana 47906., Vago FS; Department of Biological Sciences, Markey Center for Structural Biology, Purdue University, West Lafayette, Indiana 47906., Li K; Department of Biological Sciences, Markey Center for Structural Biology, Purdue University, West Lafayette, Indiana 47906., Qayyum MZ; Department of Biochemistry and Molecular Biology, The Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802., Yernool D; Department of Biological Sciences, Markey Center for Structural Biology, Purdue University, West Lafayette, Indiana 47906., Jiang W; Department of Biological Sciences, Markey Center for Structural Biology, Purdue University, West Lafayette, Indiana 47906. Electronic address: jiang12@purdue.edu., Murakami KS; Department of Biochemistry and Molecular Biology, The Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802. Electronic address: kum14@psu.edu.
Jazyk: angličtina
Zdroj: The Journal of biological chemistry [J Biol Chem] 2018 May 11; Vol. 293 (19), pp. 7367-7375. Date of Electronic Publication: 2018 Mar 26.
DOI: 10.1074/jbc.RA118.002161
Abstrakt: First step of gene expression is transcribing the genetic information stored in DNA to RNA by the transcription machinery including RNA polymerase (RNAP). In Escherichia coli , a primary σ 70 factor forms the RNAP holoenzyme to express housekeeping genes. The σ 70 contains a large insertion between the conserved regions 1.2 and 2.1, the σ non-conserved region (σ NCR ), but its function remains to be elucidated. In this study, we determined the cryo-EM structures of the E. coli RNAP σ 70 holoenzyme and its complex with promoter DNA (open complex, RPo) at 4.2 and 5.75 Å resolutions, respectively, to reveal native conformations of RNAP and DNA. The RPo structure presented here found an interaction between the σ NCR and promoter DNA just upstream of the -10 element, which was not observed in a previously determined E. coli RNAP transcription initiation complex (RPo plus short RNA) structure by X-ray crystallography because of restraint of crystal packing effects. Disruption of the σ NCR and DNA interaction by the amino acid substitutions (R157A/R157E) influences the DNA opening around the transcription start site and therefore decreases the transcription activity of RNAP. We propose that the σ NCR and DNA interaction is conserved in proteobacteria, and RNAP in other bacteria replaces its role with a transcription factor.
(© 2018 Narayanan et al.)
Databáze: MEDLINE
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