Structures and mechanism of transcription initiation by bacterial ECF factors.Fang, C., Li, L., Shen, L., Shi, J., Wang, S., Feng, Y., Zhang, Y.
(2019) Nucleic Acids Res. --: --
- PubMed: 31131408
- DOI: 10.1093/nar/gkz470
- Primary Citation of Related Structures:
- 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 at 4.0 Å of Escherichia coli transcription initiati ...
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.
Computational Bioscience Research Center (CBRC), King Abdullah University of Science and Technology (KAUST) Thuwal, 23955, Saudi Arabia.,Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200032, China.,Department of Biochemistry and Molecular Biology, School of Medicine, Zhejiang University, Hangzhou 310058, China.,University of Chinese Academy of Sciences, Beijing 100049, China.