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Title | Structures and mechanism of transcription initiation by bacterial ECF factors. |
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Journal, issue, pages | Nucleic Acids Res, Vol. 47, Issue 13, Page 7094-7104, Year 2019 |
Publish date | Jul 26, 2019 |
Authors | Chengli Fang / Lingting Li / Liqiang Shen / Jing Shi / Sheng Wang / Yu Feng / Yu Zhang / |
PubMed Abstract | Bacterial RNA polymerase (RNAP) forms distinct holoenzymes with extra-cytoplasmic function (ECF) σ factors to initiate specific gene expression programs. In this study, we report a cryo-EM structure ...Bacterial RNA polymerase (RNAP) forms distinct holoenzymes with extra-cytoplasmic function (ECF) σ factors to initiate specific gene expression programs. In this study, we report a cryo-EM structure at 4.0 Å of Escherichia coli transcription initiation complex comprising σE-the most-studied bacterial ECF σ factor (Ec σE-RPo), and a crystal structure at 3.1 Å of Mycobacterium tuberculosis transcription initiation complex with a chimeric σH/E (Mtb σH/E-RPo). The structure of Ec σE-RPo reveals key interactions essential for assembly of E. coli σE-RNAP holoenzyme and for promoter recognition and unwinding by E. coli σE. Moreover, both structures show that the non-conserved linkers (σ2/σ4 linker) of the two ECF σ factors are inserted into the active-center cleft and exit through the RNA-exit channel. We performed secondary-structure prediction of 27,670 ECF σ factors and find that their non-conserved linkers probably reach into and exit from RNAP active-center cleft in a similar manner. Further biochemical results suggest that such σ2/σ4 linker plays an important role in RPo formation, abortive production and promoter escape during ECF σ factors-mediated transcription initiation. |
External links | Nucleic Acids Res / PubMed:31131408 / PubMed Central |
Methods | EM (single particle) / X-ray diffraction |
Resolution | 2.903 - 4.02 Å |
Structure data | EMDB-9792, PDB-6jbq: PDB-6jcx: PDB-6jcy: |
Chemicals | ChemComp-MG: ChemComp-ZN: ChemComp-HOH: |
Source |
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Keywords | TRANSCRIPTION/DNA/RNA / RNA polymerase / Extra-Cytoplasmic Function sigma factors / sigmaE / transcription initiation / TRANSCRIPTION-DNA-RNA complex / TRANSCRIPTION / Mycobacterium tuberculosis / sigma H / open complex / sigma H/E |