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Zhou RW, Gordon IJ, Hei Y, Wang B. Synthetase and Hydrolase Specificity Collectively Excludes 2'-Deoxyguanosine from Bacterial Alarmone. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.06.574488. [PMID: 38260349 PMCID: PMC10802352 DOI: 10.1101/2024.01.06.574488] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
In response to starvation, virtually all bacteria pyrophosphorylate the 3'-hydroxy group of GTP or GDP to produce two messenger nucleotides collectively denoted as (p)ppGpp. Also known as alarmones, (p)ppGpp reprograms bacterial physiology to arrest growth and promote survival. Intriguingly, although cellular concentration of dGTP is two orders of magnitude lower than that of GTP, alarmone synthetases are highly selective against using 2'-deoxyguanosine (2dG) nucleotides as substrates. We thus hypothesize that production of 2dG alarmone, (p)pp(dG)pp, is highly deleterious, which drives a strong negative selection to exclude 2dG nucleotides from alarmone signaling. In this work, we show that the B. subtilis SasB synthetase prefers GDP over dGDP with 65,000-fold higher kcat/Km, a specificity stricter than RNA polymerase selecting against 2'-deoxynucleotides. Using comparative chemical proteomics, we found that although most known alarmone-binding proteins in Escherichia coli cannot distinguish ppGpp from pp(dG)pp, hydrolysis of pp(dG)pp by the essential hydrolase, SpoT, is 1,000-fold slower. This inability to degrade 2'-deoxy-3'-pyrophosphorylated substrate is a common feature of the alarmone hydrolase family. We further show that SpoT is a binuclear metallopyrophoshohydrolase and that hydrolysis of ppGpp and pp(dG)pp shares the same metal dependence. Our results support a model in which 2'-OH directly coordinates the Mn2+ at SpoT active center to stabilize the hydrolysis-productive conformation of ppGpp. Taken together, our study reveals a vital role of 2'-OH in alarmone degradation, provides new insight on the catalytic mechanism of alarmone hydrolases, and leads to the conclusion that 2dG nucleotides must be strictly excluded from alarmone synthesis because bacteria lack the key machinery to down-regulate such products.
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Affiliation(s)
- Rich W Zhou
- Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Isis J Gordon
- Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Yuanyuan Hei
- Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX 75390, USA
| | - Boyuan Wang
- Department of Pharmacology, UT Southwestern Medical Center, Dallas, TX 75390, USA
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Lin G, Barnes CO, Weiss S, Dutagaci B, Qiu C, Feig M, Song J, Lyubimov A, Cohen AE, Kaplan CD, Calero G. Structural basis of transcription: RNA Polymerase II substrate binding and metal coordination at 3.0 Å using a free-electron laser. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.22.559052. [PMID: 37790421 PMCID: PMC10543002 DOI: 10.1101/2023.09.22.559052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Catalysis and translocation of multi-subunit DNA-directed RNA polymerases underlie all cellular mRNA synthesis. RNA polymerase II (Pol II) synthesizes eukaryotic pre-mRNAs from a DNA template strand buried in its active site. Structural details of catalysis at near atomic resolution and precise arrangement of key active site components have been elusive. Here we present the free electron laser (FEL) structure of a matched ATP-bound Pol II, revealing the full active site interaction network at the highest resolution to date, including the trigger loop (TL) in the closed conformation, bonafide occupancy of both site A and B Mg2+, and a putative third (site C) Mg2+ analogous to that described for some DNA polymerases but not observed previously for cellular RNA polymerases. Molecular dynamics (MD) simulations of the structure indicate that the third Mg2+ is coordinated and stabilized at its observed position. TL residues provide half of the substrate binding pocket while multiple TL/bridge helix (BH) interactions induce conformational changes that could propel translocation upon substrate hydrolysis. Consistent with TL/BH communication, a FEL structure and MD simulations of the hyperactive Rpb1 T834P bridge helix mutant reveals rearrangement of some active site interactions supporting potential plasticity in active site function and long-distance effects on both the width of the central channel and TL conformation, likely underlying its increased elongation rate at the expense of fidelity.
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Affiliation(s)
- Guowu Lin
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh PA 15261 USA
| | - Christopher O Barnes
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena CA 91125 USA
| | - Simon Weiss
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh PA 15261 USA
| | - Bercem Dutagaci
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing MI 48824 USA
| | - Chenxi Qiu
- Department of Genetics, Harvard Medical School, Boston MA 02115 USA
| | - Michael Feig
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing MI 48824 USA
| | - Jihnu Song
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Artem Lyubimov
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Aina E Cohen
- Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, CA 94025, USA
| | - Craig D Kaplan
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh PA 15260 USA
| | - Guillermo Calero
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh PA 15261 USA
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de Mariz E Miranda LS. The synergy between nucleotide biosynthesis inhibitors and antiviral nucleosides: New opportunities against viral infections? Arch Pharm (Weinheim) 2023; 356:e2200217. [PMID: 36122181 DOI: 10.1002/ardp.202200217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Revised: 08/18/2022] [Accepted: 08/26/2022] [Indexed: 01/04/2023]
Abstract
5'-Phosphorylated nucleoside derivatives are molecules that can be found in all living organisms and viruses. Over the last century, the development of structural analogs that could disrupt the transcription and translation of genetic information culminated in the development of clinically relevant anticancer and antiviral drugs. However, clinically effective broad-spectrum antiviral compounds or treatments are lacking. This viewpoint proposes that molecules that inhibit nucleotide biosynthesis may sensitize virus-infected cells toward direct-acting antiviral nucleosides. Such potentially synergistic combinations might allow the repurposing of drugs, leading to the development of new combination therapies.
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Affiliation(s)
- Leandro S de Mariz E Miranda
- Department of Organic Chemistry, Chemistry Institute, Biocatalysis and Organic Synthesis Group, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
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Cui R, Li H, Zhao J, Li X, Gan J, Ma J. Structural insights into the dual activities of the two-barrel RNA polymerase QDE-1. Nucleic Acids Res 2022; 50:10169-10186. [PMID: 36039765 PMCID: PMC9508822 DOI: 10.1093/nar/gkac727] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Revised: 08/01/2022] [Accepted: 08/27/2022] [Indexed: 11/19/2022] Open
Abstract
Neurospora crassa protein QDE-1, a member of the two-barrel polymerase superfamily, possesses both DNA- and RNA-dependent RNA polymerase (DdRP and RdRP) activities. The dual activities are essential for the production of double-stranded RNAs (dsRNAs), the precursors of small interfering RNAs (siRNAs) in N. crassa. Here, we report five complex structures of N-terminal truncated QDE-1 (QDE-1ΔN), representing four different reaction states: DNA/RNA-templated elongation, the de novo initiation of RNA synthesis, the first step of nucleotide condensation during de novo initiation and initial NTP loading. The template strand is aligned by a bridge-helix and double-psi beta-barrels 2 (DPBB2), the RNA product is held by DPBB1 and the slab domain. The DNA template unpairs with the RNA product at position –7, but the RNA template remains paired. The NTP analog coordinates with cations and is precisely positioned at the addition site by a rigid trigger loop and a proline-containing loop in the active center. The unique C-terminal tail from the QDE-1 dimer partner inserts into the substrate-binding cleft and plays regulatory roles in RNA synthesis. Collectively, this work elucidates the conserved mechanisms for DNA/RNA-dependent dual activities by QDE-1 and other two-barrel polymerase superfamily members.
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Affiliation(s)
- Ruixue Cui
- Huashan Hospital affiliated to Fudan University, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Multiscale Research Institute of Complex Systems, Department of Biochemistry and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Hao Li
- Huashan Hospital affiliated to Fudan University, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Multiscale Research Institute of Complex Systems, Department of Biochemistry and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Jin Zhao
- Huashan Hospital affiliated to Fudan University, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Multiscale Research Institute of Complex Systems, Department of Biochemistry and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Xuhang Li
- Huashan Hospital affiliated to Fudan University, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Multiscale Research Institute of Complex Systems, Department of Biochemistry and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Jianhua Gan
- Shanghai Public Health Clinical Center, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Department of Biochemistry and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
| | - Jinbiao Ma
- Huashan Hospital affiliated to Fudan University, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Multiscale Research Institute of Complex Systems, Department of Biochemistry and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
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Shin Y, Murakami KS. Watching the bacterial RNA polymerase transcription reaction by time-dependent soak-trigger-freeze X-ray crystallography. Enzymes 2021; 49:305-314. [PMID: 34696836 DOI: 10.1016/bs.enz.2021.06.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
RNA polymerase (RNAP) is the central enzyme of gene expression, which transcribes DNA to RNA. All cellular organisms synthesize RNA with highly conserved multi-subunit DNA-dependent RNAPs, except mitochondrial RNA transcription, which is carried out by a single-subunit RNAP. Over 60 years of extensive research has elucidated the structures and functions of cellular RNAPs. In this review, we introduce a brief structural feature of bacterial RNAP, the most well characterized model enzyme, and a novel experimental approach known as "Time-dependent soak-trigger-freeze X-ray crystallography" which can be used to observe the RNA synthesis reaction at atomic resolution in real time. This principle methodology can be used for elucidating fundamental mechanisms of cellular RNAP transcription.
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Affiliation(s)
- Yeonoh Shin
- Department of Biochemistry and Molecular Biology, The Center for RNA Molecular Biology, The Pennsylvania State University, University Park, PA, United States
| | - Katsuhiko S Murakami
- Department of Biochemistry and Molecular Biology, The Center for RNA Molecular Biology, The Pennsylvania State University, University Park, PA, United States.
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Long C, Romero ME, La Rocco D, Yu J. Dissecting nucleotide selectivity in viral RNA polymerases. Comput Struct Biotechnol J 2021; 19:3339-3348. [PMID: 34104356 PMCID: PMC8175102 DOI: 10.1016/j.csbj.2021.06.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 05/28/2021] [Accepted: 06/02/2021] [Indexed: 01/18/2023] Open
Abstract
Designing antiviral therapeutics is of great concern per current pandemics caused by novel coronavirus or SARS-CoV-2. The core polymerase enzyme in the viral replication/transcription machinery is generally conserved and serves well for drug target. In this work we briefly review structural biology and computational clues on representative single-subunit viral polymerases that are more or less connected with SARS-CoV-2 RNA dependent RNA polymerase (RdRp), in particular, to elucidate how nucleotide substrates and potential drug analogs are selected in the viral genome synthesis. To do that, we first survey two well studied RdRps from Polio virus and hepatitis C virus in regard to structural motifs and key residues that have been identified for the nucleotide selectivity. Then we focus on related structural and biochemical characteristics discovered for the SARS-CoV-2 RdRp. To further compare, we summarize what we have learned computationally from phage T7 RNA polymerase (RNAP) on its stepwise nucleotide selectivity, and extend discussion to a structurally similar human mitochondria RNAP, which deserves special attention as it cannot be adversely affected by antiviral treatments. We also include viral phi29 DNA polymerase for comparison, which has both helicase and proofreading activities on top of nucleotide selectivity for replication fidelity control. The helicase and proofreading functions are achieved by protein components in addition to RdRp in the coronavirus replication-transcription machine, with the proofreading strategy important for the fidelity control in synthesizing a comparatively large viral genome.
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Affiliation(s)
- Chunhong Long
- School of Science, Chongqing University of Posts and Telecommunications, Chongqing 400065, China
| | | | - Daniel La Rocco
- Department of Physics, University of California, Berkeley, CA 94720, USA
| | - Jin Yu
- Department of Physics and Astronomy, Department of Chemistry, NSF-Simons Center for Multiscale Cell Fate Research, University of California, Irvine, CA 92697, USA
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Strobel EJ. Preparation of E. coli RNA polymerase transcription elongation complexes by selective photoelution from magnetic beads. J Biol Chem 2021; 297:100812. [PMID: 34023383 PMCID: PMC8212663 DOI: 10.1016/j.jbc.2021.100812] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 05/17/2021] [Accepted: 05/19/2021] [Indexed: 11/30/2022] Open
Abstract
In vitro studies of transcription frequently require the preparation of defined elongation complexes. Defined transcription elongation complexes (TECs) are typically prepared by constructing an artificial transcription bubble from synthetic oligonucleotides and RNA polymerase. This approach is optimal for diverse applications but is sensitive to nucleic acid length and sequence and is not compatible with systems where promoter-directed initiation or extensive transcription elongation is crucial. To complement scaffold-directed approaches for TEC assembly, I have developed a method for preparing promoter-initiated Escherichia coli TECs using a purification strategy called selective photoelution. This approach combines TEC-dependent sequestration of a biotin-triethylene glycol transcription stall site with photoreversible DNA immobilization to enrich TECs from an in vitro transcription reaction. I show that selective photoelution can be used to purify TECs that contain a 273-bp DNA template and 194-nt structured RNA. Selective photoelution is a straightforward and robust procedure that, in the systems assessed here, generates precisely positioned TECs with >95% purity and >30% yield. TECs prepared by selective photoelution can contain complex nucleic acid sequences and will therefore likely be useful for investigating RNA structure and function in the context of RNA polymerases.
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Affiliation(s)
- Eric J Strobel
- Department of Biological Sciences, The University at Buffalo, Buffalo, New York, USA.
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