This proposal focuses on transcription initiation and elongation by bacterial RNA polymerase (RNAP). Transcription initiation and elongation involve a series of steps: (i) RNAP binds to promoter DNA, yielding an RNAP-promoter closed complex;(ii) RNAP unwinds promoter DNA, yielding an RNAP-promoter open complex;(iii) RNAP synthesizes the first ~11 nucleotides of RNA as an RNAP-promoter initial transcribing complex, using a """"""""scrunching"""""""" mechanism, in which RNAP remains stationary on promoter DNA and pulls in adjacent DNA in each nucleotide-addition cycle;and (iv) RNAP breaks its interactions with promoter DNA and synthesizes the remaining nucleotides of RNA as an RNAP-DNA elongation complex, using a """"""""stepping"""""""" mechanism, in which RNAP moves forward on DNA in each nucleotide-addition cycle. Each of these steps is a potential target for transcriptional regulators Understanding transcription initiation, transcription elongation, and transcriptional regulation wil require defining the structural transitions in protein and DNA at each step, the kinetics of structural transitions, and the mechanisms by which regulators affect structural transitions. In the current period, we identified a new crystal form that enables high-resolution structural studies of the RNAP-promoter open complex (RPo) and the RNAP-promoter initial transcribing complex (RPitc), we determined the first high-resolution structure of RPo, and we delineated a DNA sequence element recognized by RNAP (the """"""""core recognition element,"""""""" CRE). In other work in the current period, we developed a single-molecule-fluorescence assay that enables the monitoring of RNAP clamp conformation in solution, and we defined RNAP clamp conformation at each step in transcription initiation. The proposed work will build on the findings of the curret period. The proposed work will use x-ray crystallography, single-molecule biophysics, biochemistry, and genetics to address five specific aims:
Specific Aim 1 : Determination of the structural basis of de novo transcription initiation Specific Aim 2: Determination of the structura basis of initial transcription Specific Aim 3: Analysis of RNAP-CRE interactions in transcription initiation Specific Aim 4: Analysis of RNAP-CRE interactions in transcription elongation Specific Aim 5: Analysis of RNAP clamp conformation in transcription elongation The results will contribute to understanding bacterial transcription and transcriptional regulation, and will contribute to design and synthesis of small-molecule inhibitors of bacterial transcription, for use in antibacterial therapy. Since bacterial RNAP shows sequence, structural, and mechanistic similarities to eukaryotic RNAP, the results also will contribute to understanding eukaryotic transcription and transcriptional regulation.

Public Health Relevance

Bacterial RNA polymerase (RNAP) is a molecular machine that carries out reactions essential for bacterial gene expression and bacterial growth. Two classes of current antibacterial drugs function by inhibiting RNAP. The proposed work will provide information essential for understanding the mechanism of action of RNAP and for rational design of improved and novel antibacterial drugs that function by inhibiting RNAP.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Method to Extend Research in Time (MERIT) Award (R37)
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Prokaryotic Cell and Molecular Biology Study Section (PCMB)
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Preusch, Peter
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Rutgers University
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New Brunswick
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Gabizon, Ronen; Lee, Antony; Vahedian-Movahed, Hanif et al. (2018) Pause sequences facilitate entry into long-lived paused states by reducing RNA polymerase transcription rates. Nat Commun 9:2930
Vvedenskaya, Irina O; Bird, Jeremy G; Zhang, Yuanchao et al. (2018) CapZyme-Seq Comprehensively Defines Promoter-Sequence Determinants for RNA 5' Capping with NAD. Mol Cell 70:553-564.e9
Lin, Wei; Das, Kalyan; Degen, David et al. (2018) Structural Basis of Transcription Inhibition by Fidaxomicin (Lipiarmycin A3). Mol Cell 70:60-71.e15
Duchi, Diego; Mazumder, Abhishek; Malinen, Anssi M et al. (2018) The RNA polymerase clamp interconverts dynamically among three states and is stabilized in a partly closed state by ppGpp. Nucleic Acids Res 46:7284-7295
Sosio, Margherita; Gaspari, Eleonora; Iorio, Marianna et al. (2018) Analysis of the Pseudouridimycin Biosynthetic Pathway Provides Insights into the Formation of C-nucleoside Antibiotics. Cell Chem Biol 25:540-549.e4
Maffioli, Sonia I; Sosio, Margherita; Ebright, Richard H et al. (2018) Discovery, properties, and biosynthesis of pseudouridimycin, an antibacterial nucleoside-analog inhibitor of bacterial RNA polymerase. J Ind Microbiol Biotechnol :
Walker, Scott S; Degen, David; Nickbarg, Elliott et al. (2017) Affinity Selection-Mass Spectrometry Identifies a Novel Antibacterial RNA Polymerase Inhibitor. ACS Chem Biol 12:1346-1352
Maffioli, Sonia I; Zhang, Yu; Degen, David et al. (2017) Antibacterial Nucleoside-Analog Inhibitor of Bacterial RNA Polymerase. Cell 169:1240-1248.e23
Lin, Wei; Mandal, Soma; Degen, David et al. (2017) Structural Basis of Mycobacterium tuberculosis Transcription and Transcription Inhibition. Mol Cell 66:169-179.e8
Yu, Libing; Winkelman, Jared T; Pukhrambam, Chirangini et al. (2017) The mechanism of variability in transcription start site selection. Elife 6:

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