1
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Esser A, Mayer G. Characterization of the glmS Ribozymes from Listeria Monocytogenes and Clostridium Difficile. Chemistry 2023; 29:e202202376. [PMID: 36194523 PMCID: PMC10099748 DOI: 10.1002/chem.202202376] [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: 07/30/2022] [Indexed: 11/23/2022]
Abstract
The glmS ribozyme regulates the expression of the essential GlmS enzyme being involved in cell wall biosynthesis. While >450 variants of the glmS ribozyme were identified by in silico approaches and homology searches, only a few have yet been experimentally investigated. Herein, we validate and characterize the glmS ribozymes of the human pathogens Clostridium difficile and Listeria monocytogenes. Both ribozymes, as their previous characterized homologs rely on glucosamine-6-phosphate as co-factor and the presence of divalent cations for exerting the cleavage reaction. The observed EC50 values in turn were found to be in the submicromolar range, at least an order of magnitude lower than observed for glmS ribozymes from other bacteria. The glmS ribozyme of L. monocytogenes was further shown to bear unique properties. It discriminates between co-factors very stringently and other than the glmS ribozyme of C. difficile retains activity at low temperatures. This finding illustrates that albeit being highly conserved, glmS ribozymes have unique characteristics.
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Affiliation(s)
- Anna Esser
- Life & Medical Sciences Institute, University of Bonn, Gerhard-Domagk-Str. 1, 53121, Bonn, Germany
| | - Günter Mayer
- Life & Medical Sciences Institute, University of Bonn, Gerhard-Domagk-Str. 1, 53121, Bonn, Germany.,Center of Aptamer Research & Development, University of Bonn, Gerhard-Domagk-Str. 1, 53121, Bonn, Germany
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2
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Aroonsri A, Kongsee J, Gunawan JD, Aubry DA, Shaw PJ. A cell-based ribozyme reporter system employing a chromosomally-integrated 5' exonuclease gene. BMC Mol Cell Biol 2021; 22:20. [PMID: 33726662 PMCID: PMC7967978 DOI: 10.1186/s12860-021-00357-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2020] [Accepted: 02/28/2021] [Indexed: 11/10/2022] Open
Abstract
Background Bioinformatic genome surveys indicate that self-cleaving ribonucleic acids (ribozymes) appear to be widespread among all domains of life, although the functions of only a small number have been validated by biochemical methods. Alternatively, cell-based reporter gene assays can be used to validate ribozyme function. However, reporter activity can be confounded by phenomena unrelated to ribozyme-mediated cleavage of RNA. Results We established a ribozyme reporter system in Escherichia coli in which a significant reduction of reporter activity is manifest when an active ribozyme sequence is fused to the reporter gene and the expression of a foreign Bacillus subtilis RNaseJ1 5′ exonuclease is induced from a chromosomally-integrated gene in the same cell. Conclusions The reporter system could be useful for validating ribozyme function in candidate sequences identified from bioinformatics. Supplementary Information The online version contains supplementary material available at 10.1186/s12860-021-00357-7.
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Affiliation(s)
- Aiyada Aroonsri
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathum Thani, 12120, Thailand.
| | - Jindaporn Kongsee
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathum Thani, 12120, Thailand
| | - Jeremy David Gunawan
- School of Life Science, Indonesia International Institute for Life Sciences (i3L), Jakarta, 13210, Indonesia
| | - Daniel Abidin Aubry
- School of Life Science, Indonesia International Institute for Life Sciences (i3L), Jakarta, 13210, Indonesia
| | - Philip James Shaw
- National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), Pathum Thani, 12120, Thailand
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3
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Dönmüş B, Ünal S, Kirmizitaş FC, Türkoğlu Laçin N. Virus-associated ribozymes and nano carriers against COVID-19. ARTIFICIAL CELLS NANOMEDICINE AND BIOTECHNOLOGY 2021; 49:204-218. [PMID: 33645342 DOI: 10.1080/21691401.2021.1890103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a zoo tonic, highly pathogenic virus. The new type of coronavirus with contagious nature spread from Wuhan (China) to the whole world in a very short time and caused the new coronavirus disease (COVID-19). COVID-19 has turned into a global public health crisis due to spreading by close person-to-person contact with high transmission capacity. Thus, research about the treatment of the damages caused by the virus or prevention from infection increases everyday. Besides, there is still no approved and definitive, standardized treatment for COVID-19. However, this disaster experienced by human beings has made us realize the significance of having a system ready for use to prevent humanity from viral attacks without wasting time. As is known, nanocarriers can be targeted to the desired cells in vitro and in vivo. The nano-carrier system targeting a specific protein, containing the enzyme inhibiting the action of the virus can be developed. The system can be used by simple modifications when we encounter another virus epidemic in the future. In this review, we present a potential treatment method consisting of a nanoparticle-ribozyme conjugate, targeting ACE-2 receptors by reviewing the virus-associated ribozymes, their structures, types and working mechanisms.
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Affiliation(s)
- Beyza Dönmüş
- Molecular Biology and Genetics Department, Yıldız Technical University, Istanbul, Turkey
| | - Sinan Ünal
- Molecular Biology and Genetics Department, Yıldız Technical University, Istanbul, Turkey
| | - Fatma Ceren Kirmizitaş
- Molecular Biology and Genetics Department, Yıldız Technical University, Istanbul, Turkey
| | - Nelisa Türkoğlu Laçin
- Molecular Biology and Genetics Department, Yıldız Technical University, Istanbul, Turkey
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4
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Maurel MC, Leclerc F, Hervé G. Ribozyme Chemistry: To Be or Not To Be under High Pressure. Chem Rev 2019; 120:4898-4918. [DOI: 10.1021/acs.chemrev.9b00457] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Marie-Christine Maurel
- Institut de Systématique, Evolution, Biodiversité (ISYEB), CNRS, Sorbonne Université, Muséum National d’Histoire Naturelle, EPHE, F-75005 Paris, France
| | - Fabrice Leclerc
- Institute for Integrative Biology of the Cell (I2BC), CNRS, CEA, Université Paris Sud, F-91198 Gif-sur-Yvette, France
| | - Guy Hervé
- Laboratoire BIOSIPE, Sorbonne Université, CNRS, Institut de Biologie Paris-Seine, Campus Pierre et Marie Curie, F-75005 Paris, France
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5
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Deng C, Lv X, Liu Y, Li J, Lu W, Du G, Liu L. Metabolic engineering of Corynebacterium glutamicum S9114 based on whole-genome sequencing for efficient N-acetylglucosamine synthesis. Synth Syst Biotechnol 2019; 4:120-129. [PMID: 31198861 PMCID: PMC6558094 DOI: 10.1016/j.synbio.2019.05.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Revised: 05/30/2019] [Accepted: 05/30/2019] [Indexed: 12/26/2022] Open
Abstract
Glucosamine (GlcN) and its acetylated derivative N-acetylglucosamine (GlcNAc) are widely used in the pharmaceutical industries. Here, we attempted to achieve efficient production of GlcNAc via genomic engineering of Corynebacterium glutamicum. Specifically, we ligated the GNA1 gene, which converts GlcN-6-phosphate to GlcNAc-6-phosphate by transferring the acetyl group in Acetyl-CoA to the amino group of GlcN-6-phosphate, into the plasmid pJYW4 and then transformed this recombinant vector into the C. glutamicum ATCC 13032, ATCC 13869, ATCC 14067, and S9114 strains, and we assessed the GlcNAc titers at 0.5 g/L, 1.2 g/L, 0.8 g/L, and 3.1 g/L from each strain, respectively. This suggested that there were likely to be significant differences among the key genes in the glutamate and GlcNAc synthesis pathways of these C. glutamicum strains. Therefore, we performed whole genome sequencing of the S9114 strain, which has not been previously published, and found that there are many differences among the genes in the glutamate and GlcNAc synthesis pathways among the four strains tested. Next, nagA (encoding GlcNAc-6-phosphate deacetylase) and gamA (encoding GlcN-6-phosphate deaminase) were deleted in C. glutamicum S9114 to block the catabolism of intracellular GlcNAc, leading to a 54.8% increase in GlcNAc production (from 3.1 to 4.8 g/L) when grown in a shaker flask. In addition, lactate synthesis was blocked by knockout of ldh (encoding lactate dehydrogenase); thus, further increasing the GlcNAc titer to 5.4 g/L. Finally, we added a key gene of the GlcN synthetic pathway, glmS, from different sources into the expression vector pJYW-4-ceN, and the resulting recombinant strain CGGN2-GNA1-CgglmS produced the GlcNAc titer of 6.9 g/L. This is the first report concerning the metabolic engineering of C. glutamicum, and the results of this study provide a good starting point for further metabolic engineering to achieve industrial-scale production of GlcNAc.
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Affiliation(s)
- Chen Deng
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Xueqin Lv
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Yanfeng Liu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Jianghua Li
- Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Wei Lu
- Shandong Runde Biotechnology CO., LTD, Taian, 271200, China
| | - Guocheng Du
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Long Liu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China.,Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi, 214122, China
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6
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Self-cleavage of the glmS ribozyme core is controlled by a fragile folding element. Proc Natl Acad Sci U S A 2018; 115:11976-11981. [PMID: 30397151 DOI: 10.1073/pnas.1812122115] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Riboswitches modulate gene expression in response to small-molecule ligands. Switching is generally thought to occur via the stabilization of a specific RNA structure conferred by binding the cognate ligand. However, it is unclear whether any such stabilization occurs for riboswitches whose ligands also play functional roles, such as the glmS ribozyme riboswitch, which undergoes self-cleavage using its regulatory ligand, glucosamine 6-phosphate, as a catalytic cofactor. To address this question, it is necessary to determine both the conformational ensemble and its ligand dependence. We used optical tweezers to measure folding dynamics and cleavage rates for the core glmS ribozyme over a range of forces and ligand conditions. We found that the folding of a specific structural element, the P2.2 duplex, controls active-site formation and catalysis. However, the folded state is only weakly stable, regardless of cofactor concentration, supplying a clear exception to the ligand-based stabilization model of riboswitch function.
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7
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Sergeeva OV, Bredikhin DO, Nesterchuk MV, Serebryakova MV, Sergiev PV, Dontsova OA. Possible Role of Escherichia coli Protein YbgI. BIOCHEMISTRY (MOSCOW) 2018; 83:270-280. [PMID: 29625546 DOI: 10.1134/s0006297918030070] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Proteins containing the NIF3 domain are highly conserved and are found in bacteria, eukaryotes, and archaea. YbgI is an Escherichia coli protein whose gene is conserved among bacteria. The structure of YbgI is known; however, the function of this protein in cells remains obscure. Our studies of E. coli cells with deleted ybgI gene suggest that YbgI is involved in formation of the bacterial cell wall.
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Affiliation(s)
- O V Sergeeva
- Skolkovo Institute of Science and Technology, 143026 Skolkovo, Moscow Region, Russia.
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8
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Wang TP, Su YC, Chen Y, Severance S, Hwang CC, Liou YM, Lu CH, Lin KL, Zhu RJ, Wang EC. Corroboration of Zn( ii)–Mg( ii)-tertiary structure interplays essential for the optimal catalysis of a phosphorothiolate thiolesterase ribozyme. RSC Adv 2018; 8:32775-32793. [PMID: 35547718 PMCID: PMC9086351 DOI: 10.1039/c8ra05083j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 09/06/2018] [Indexed: 11/21/2022] Open
Abstract
The TW17 ribozyme, a catalytic RNA selected from a pool of artificial RNA, is specific for the Zn2+-dependent hydrolysis of a phosphorothiolate thiolester bond. Here, we describe the organic synthesis of both guanosine α-thio-monophosphate and the substrates required for selecting and characterizing the TW17 ribozyme, and for deciphering the catalytic mechanism of the ribozyme. By successively substituting the substrate originally conjugated to the RNA pool with structurally modified substrates, we demonstrated that the TW17 ribozyme specifically catalyzes phosphorothiolate thiolester hydrolysis. Metal titration studies of TW17 ribozyme catalysis in the presence of Zn2+ alone, Zn2+ and Mg2+, and Zn2+ and [Co(NH3)6]3+ supported our findings that Zn2+ is absolutely required for ribozyme catalysis, and indicated that optimal ribozyme catalysis involves the presence of outer-sphere and one inner-sphere Mg2+. A survey of the TW17 ribozyme activity at various pHs revealed that the activity of the ribozyme critically depends on the alkaline conditions. Moreover, a GNRA tetraloop-containing ribozyme constructed with active catalysis in trans provided catalysis and multiple substrate turnover efficiencies significantly higher than ribozymes lacking a GNRA tetraloop. This research supports the essential roles of Zn2+, Mg2+, and a GNRA tetraloop in modulating the TW17 ribozyme structure for optimal ribozyme catalysis, leading also to the formulation of a proposed reaction mechanism for TW17 ribozyme catalysis. Zn(ii) and Mg(ii) and GAGA tetraloop in the ion atmosphere of the TW17 ribozyme is critical to optimal ribozyme catalysis at alkaline pH.![]()
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Affiliation(s)
- Tzu-Pin Wang
- Department of Medicinal and Applied Chemistry
- Kaohsiung Medical University
- Kaohsiung
- Taiwan
- Kaohsiung Medical University Hospital
| | - Yu-Chih Su
- Department of Medicinal and Applied Chemistry
- Kaohsiung Medical University
- Kaohsiung
- Taiwan
| | - Yi Chen
- Department of Medicinal and Applied Chemistry
- Kaohsiung Medical University
- Kaohsiung
- Taiwan
| | - Scott Severance
- Department of Molecular and Cellular Sciences
- Liberty University College of Osteopathic Medicine
- Lynchburg
- USA
| | - Chi-Ching Hwang
- Department of Biochemistry
- Kaohsiung Medical University
- Kaohsiung
- Taiwan
| | - Yi-Ming Liou
- Department of Medicinal and Applied Chemistry
- Kaohsiung Medical University
- Kaohsiung
- Taiwan
| | - Chia-Hui Lu
- Department of Medicinal and Applied Chemistry
- Kaohsiung Medical University
- Kaohsiung
- Taiwan
| | - Kun-Liang Lin
- Department of Medicinal and Applied Chemistry
- Kaohsiung Medical University
- Kaohsiung
- Taiwan
| | - Rui Jing Zhu
- Department of Medicinal and Applied Chemistry
- Kaohsiung Medical University
- Kaohsiung
- Taiwan
| | - Eng-Chi Wang
- Department of Medicinal and Applied Chemistry
- Kaohsiung Medical University
- Kaohsiung
- Taiwan
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9
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Bingaman JL, Zhang S, Stevens DR, Yennawar NH, Hammes-Schiffer S, Bevilacqua PC. The GlcN6P cofactor plays multiple catalytic roles in the glmS ribozyme. Nat Chem Biol 2017; 13:439-445. [PMID: 28192411 PMCID: PMC5362308 DOI: 10.1038/nchembio.2300] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2016] [Accepted: 12/09/2016] [Indexed: 01/06/2023]
Abstract
RNA enzymes (ribozymes) have remarkably diverse biological roles despite having limited chemical diversity. Protein enzymes enhance their reactivity through recruitment of cofactors; likewise, the naturally occurring glmS ribozyme uses the glucosamine-6-phosphate (GlcN6P) organic cofactor for phosphodiester bond cleavage. Prior structural and biochemical studies have implicated GlcN6P as the general acid. Here we describe new catalytic roles of GlcN6P through experiments and calculations. Large stereospecific normal thio effects and a lack of metal-ion rescue in the holoribozyme indicate that nucleobases and the cofactor play direct chemical roles and align the active site for self-cleavage. Large stereospecific inverse thio effects in the aporibozyme suggest that the GlcN6P cofactor disrupts an inhibitory interaction of the nucleophile. Strong metal-ion rescue in the aporibozyme reveals that this cofactor also provides electrostatic stabilization. Ribozyme organic cofactors thus perform myriad catalytic roles, thereby allowing RNA to compensate for its limited functional diversity.
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Affiliation(s)
- Jamie L. Bingaman
- Department of Chemistry and Center for RNA Molecular
Biology, The Pennsylvania State University, University Park, Pennsylvania 16802,
United States
| | - Sixue Zhang
- Department of Chemistry, University of Illinois at
Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United
States
| | - David R. Stevens
- Department of Chemistry, University of Illinois at
Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United
States
| | - Neela H. Yennawar
- X-ray Crystallography Facility, Huck Institutes of the Life
Sciences, The Pennsylvania State University, 8 Althouse Laboratory, University Park,
Pennsylvania 16802, United States
| | - Sharon Hammes-Schiffer
- Department of Chemistry, University of Illinois at
Urbana-Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United
States
| | - Philip C. Bevilacqua
- Department of Chemistry and Center for RNA Molecular
Biology, The Pennsylvania State University, University Park, Pennsylvania 16802,
United States
- Department of Biochemistry and Molecular Biology, The
Pennsylvania State University, University Park, Pennsylvania 16802, United
States
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10
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Bingaman JL, Messina KJ, Bevilacqua PC. Probing fast ribozyme reactions under biological conditions with rapid quench-flow kinetics. Methods 2017; 120:125-134. [PMID: 28315484 DOI: 10.1016/j.ymeth.2017.03.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Revised: 02/28/2017] [Accepted: 03/10/2017] [Indexed: 11/24/2022] Open
Abstract
Reaction kinetics on the millisecond timescale pervade the protein and RNA fields. To study such reactions, investigators often perturb the system with abiological solution conditions or substrates in order to slow the rate to timescales accessible by hand mixing; however, such perturbations can change the rate-limiting step and obscure key folding and chemical steps that are found under biological conditions. Mechanical methods for collecting data on the millisecond timescale, which allow these perturbations to be avoided, have been developed over the last few decades. These methods are relatively simple and can be conducted on affordable and commercially available instruments. Here, we focus on using the rapid quench-flow technique to study the fast reaction kinetics of RNA enzymes, or ribozymes, which often react on the millisecond timescale under biological conditions. Rapid quench of ribozymes is completely parallel to the familiar hand-mixing approach, including the use of radiolabeled RNAs and fractionation of reactions on polyacrylamide gels. We provide tips on addressing and preventing common problems that can arise with the rapid-quench technique. Guidance is also offered on ensuring the ribozyme is properly folded and fast-reacting. We hope that this article will facilitate the broader use of rapid-quench instrumentation to study fast-reacting ribozymes under biological reaction conditions.
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Affiliation(s)
- Jamie L Bingaman
- Department of Chemistry and Center for RNA Molecular Biology, The Pennsylvania State University, University Park, PA 16802, United States.
| | - Kyle J Messina
- Department of Chemistry and Center for RNA Molecular Biology, The Pennsylvania State University, University Park, PA 16802, United States
| | - Philip C Bevilacqua
- Department of Chemistry and Center for RNA Molecular Biology, The Pennsylvania State University, University Park, PA 16802, United States; Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, United States.
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11
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Tools for attenuation of gene expression in malaria parasites. Int J Parasitol 2017; 47:385-398. [PMID: 28153780 DOI: 10.1016/j.ijpara.2016.11.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 09/15/2016] [Accepted: 11/28/2016] [Indexed: 12/30/2022]
Abstract
An understanding of the biology of Plasmodium parasites, which are the causative agents of the disease malaria, requires study of gene function. Various reverse genetic tools have been described for determining gene function. These tools can be broadly grouped as trans- and cis-acting. Trans-acting tools control gene functions through synthetic nucleic acid probe molecules matching the sequence of the gene of interest. Once delivered to the parasite, the probe engages with the mRNA of the target gene and attenuates its function. Cis-acting tools control gene function through elements introduced into the gene of interest by DNA transfection. The expression of the modified gene can be controlled using external agents, typically small molecule ligands. In this review, we discuss the strengths and weaknesses of these tools to guide researchers in selecting the appropriate tool for studies of gene function, and for guiding future refinements of these tools.
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12
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High-throughput strategies for the discovery and engineering of enzymes for biocatalysis. Bioprocess Biosyst Eng 2016; 40:161-180. [DOI: 10.1007/s00449-016-1690-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 10/05/2016] [Indexed: 12/16/2022]
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13
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Zhang S, Stevens D, Goyal P, Bingaman JL, Bevilacqua PC, Hammes-Schiffer S. Assessing the Potential Effects of Active Site Mg 2+ Ions in the glmS Ribozyme-Cofactor Complex. J Phys Chem Lett 2016; 7:3984-3988. [PMID: 27677922 PMCID: PMC5117136 DOI: 10.1021/acs.jpclett.6b01854] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 09/14/2016] [Indexed: 06/06/2023]
Abstract
Ribozymes employ diverse catalytic strategies in their self-cleavage mechanisms, including the use of divalent metal ions. This work explores the effects of Mg2+ ions in the active site of the glmS ribozyme-GlcN6P cofactor complex using computational methods. Deleterious and potentially beneficial effects of an active site Mg2+ ion on the self-cleavage reaction were identified. The presence of a Mg2+ ion near the scissile phosphate oxygen atoms at the cleavage site was determined to be deleterious, and thereby anticatalytic, due to electrostatic repulsion of the cofactor, disruption of key hydrogen-bonding interactions, and obstruction of nucleophilic attack. On the other hand, the presence of a Mg2+ ion at another position in the active site, the Hoogsteen face of the putative base, was found to avoid these deleterious effects and to be potentially catalytically favorable owing to the stabilization of negative charge and pKa shifting of the guanine base.
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Affiliation(s)
- Sixue Zhang
- Department
of Chemistry, University of Illinois at
Urbana−Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801-3364, United States
| | - David
R. Stevens
- Department
of Chemistry, University of Illinois at
Urbana−Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801-3364, United States
| | - Puja Goyal
- Department
of Chemistry, University of Illinois at
Urbana−Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801-3364, United States
| | - Jamie L. Bingaman
- Department of Chemistry and Center
for RNA Molecular Biology and Department of Biochemistry
and Molecular Biology, The Pennsylvania
State University, University Park, Pennsylvania 16802, United States
| | - Philip C. Bevilacqua
- Department of Chemistry and Center
for RNA Molecular Biology and Department of Biochemistry
and Molecular Biology, The Pennsylvania
State University, University Park, Pennsylvania 16802, United States
| | - Sharon Hammes-Schiffer
- Department
of Chemistry, University of Illinois at
Urbana−Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801-3364, United States
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14
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Abstract
Metal ions are essential cofactors for the structure and functions of nucleic acids. Yet, the early discovery in the 70s of the crucial role of Mg(2+) in stabilizing tRNA structures has occulted for a long time the importance of monovalent cations. Renewed interest in these ions was brought in the late 90s by the discovery of specific potassium metal ions in the core of a group I intron. Their importance in nucleic acid folding and catalytic activity is now well established. However, detection of K(+) and Na(+) ions is notoriously problematic and the question about their specificity is recurrent. Here we review the different methods that can be used to detect K(+) and Na(+) ions in nucleic acid structures such as X-ray crystallography, nuclear magnetic resonance or molecular dynamics simulations. We also discuss specific versus non-specific binding to different structures through various examples.
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Affiliation(s)
- Pascal Auffinger
- Architecture et Réactivité de l'ARN, Université de Strasbourg, IBMC, CNRS, 15 rue René Descartes, F-67084, Strasbourg, France.
| | - Luigi D'Ascenzo
- Architecture et Réactivité de l'ARN, Université de Strasbourg, IBMC, CNRS, 15 rue René Descartes, F-67084, Strasbourg, France.
| | - Eric Ennifar
- Architecture et Réactivité de l'ARN, Université de Strasbourg, IBMC, CNRS, 15 rue René Descartes, F-67084, Strasbourg, France.
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15
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Mir A, Chen J, Robinson K, Lendy E, Goodman J, Neau D, Golden BL. Two Divalent Metal Ions and Conformational Changes Play Roles in the Hammerhead Ribozyme Cleavage Reaction. Biochemistry 2015; 54:6369-81. [PMID: 26398724 PMCID: PMC4710350 DOI: 10.1021/acs.biochem.5b00824] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The hammerhead ribozyme is a self-cleaving RNA broadly dispersed across all kingdoms of life. Although it was the first of the small, nucleolytic ribozymes discovered, the mechanism by which it catalyzes its reaction remains elusive. The nucleobase of G12 is well positioned to be a general base, but it is unclear if or how this guanine base becomes activated for proton transfer. Metal ions have been implicated in the chemical mechanism, but no interactions between divalent metal ions and the cleavage site have been observed crystallographically. To better understand how this ribozyme functions, we have solved crystal structures of wild-type and G12A mutant ribozymes. We observe a pH-dependent conformational change centered around G12, consistent with this nucleotide becoming deprotonated. Crystallographic and kinetic analysis of the G12A mutant reveals a Zn(2+) specificity switch suggesting a direct interaction between a divalent metal ion and the purine at position 12. The metal ion specificity switch and the pH-rate profile of the G12A mutant suggest that the minor imino tautomer of A12 serves as the general base in the mutant ribozyme. We propose a model in which the hammerhead ribozyme rearranges prior to the cleavage reaction, positioning two divalent metal ions in the process. The first metal ion, positioned near G12, becomes directly coordinated to the O6 keto oxygen, to lower the pKa of the general base and organize the active site. The second metal ion, positioned near G10.1, bridges the N7 of G10.1 and the scissile phosphate and may participate directly in the cleavage reaction.
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Affiliation(s)
- Aamir Mir
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Ji Chen
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Kyle Robinson
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Emma Lendy
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - Jaclyn Goodman
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907, United States
| | - David Neau
- Department of Chemistry and Chemical Biology, Cornell University, Northeastern Collaborative Access Team, Argonne National Laboratory, Argonne, Illinois 60439, United States
| | - Barbara L. Golden
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907, United States,Corresponding Author: Telephone: (765) 496-6165;
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16
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Dubecký M, Walter NG, Šponer J, Otyepka M, Banáš P. Chemical feasibility of the general acid/base mechanism of glmS ribozyme self-cleavage. Biopolymers 2015; 103:550-62. [PMID: 25858644 PMCID: PMC4553064 DOI: 10.1002/bip.22657] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Revised: 03/17/2015] [Accepted: 04/02/2015] [Indexed: 01/28/2023]
Abstract
In numerous Gram-positive bacteria, the glmS ribozyme or catalytic riboswitch regulates the expression of glucosamine-6-phosphate (GlcN6P) synthase via site-specific cleavage of its sugar-phosphate backbone in response to GlcN6P ligand binding. Biochemical data have suggested a crucial catalytic role for an active site guanine (G40 in Thermoanaerobacter tengcongensis, G33 in Bacillus anthracis). We used hybrid quantum chemical/molecular mechanical (QM/MM) calculations to probe the mechanism where G40 is deprotonated and acts as a general base. The calculations suggest that the deprotonated guanine G40(-) is sufficiently reactive to overcome the thermodynamic penalty arising from its rare protonation state, and thus is able to activate the A-1(2'-OH) group toward nucleophilic attack on the adjacent backbone. Furthermore, deprotonation of A-1(2'-OH) and nucleophilic attack are predicted to occur as separate steps, where activation of A-1(2'-OH) precedes nucleophilic attack. Conversely, the transition state associated with the rate-determining step corresponds to concurrent nucleophilic attack and protonation of the G1(O5') leaving group by the ammonium moiety of the GlcN6P cofactor. Overall, our calculations help to explain the crucial roles of G40 (as a general base) and GlcN6P (as a general acid) during glmS ribozyme self-cleavage. In addition, we show that the QM/MM description of the glmS ribozyme self-cleavage reaction is significantly more sensitive to the size of the QM region and the quality of the QM-MM coupling than that of other small ribozymes.
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Affiliation(s)
- Matúš Dubecký
- Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University, tř. 17 listopadu 12, 771 46, Olomouc, Czech Republic
| | - Nils G. Walter
- Department of Chemistry, Single Molecule Analysis Group, University of Michigan, 930 North University Avenue, Ann Arbor, Michigan 48109-1055
| | - Jiří Šponer
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, 612 65 Brno, Czech Republic
- CEITEC – Central European Institute of Technology, Campus Bohunice, Kamenice 5, 625 00
| | - Michal Otyepka
- Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University, tř. 17 listopadu 12, 771 46, Olomouc, Czech Republic
| | - Pavel Banáš
- Regional Centre of Advanced Technologies and Materials, Department of Physical Chemistry, Faculty of Science, Palacký University, tř. 17 listopadu 12, 771 46, Olomouc, Czech Republic
- Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, 612 65 Brno, Czech Republic
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17
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Dong X, Tian Z, Yang X, Xue Y. Theoretical study on the mechanism of self-cleavage reaction of the glmS ribozyme. Theor Chem Acc 2015. [DOI: 10.1007/s00214-015-1667-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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18
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Zhang S, Ganguly A, Goyal P, Bingaman J, Bevilacqua PC, Hammes-Schiffer S. Role of the active site guanine in the glmS ribozyme self-cleavage mechanism: quantum mechanical/molecular mechanical free energy simulations. J Am Chem Soc 2015; 137:784-98. [PMID: 25526516 PMCID: PMC4308743 DOI: 10.1021/ja510387y] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Indexed: 11/30/2022]
Abstract
The glmS ribozyme catalyzes a self-cleavage reaction at the phosphodiester bond between residues A-1 and G1. This reaction is thought to occur by an acid-base mechanism involving the glucosamine-6-phosphate cofactor and G40 residue. Herein quantum mechanical/molecular mechanical free energy simulations and pKa calculations, as well as experimental measurements of the rate constant for self-cleavage, are utilized to elucidate the mechanism, particularly the role of G40. Our calculations suggest that an external base deprotonates either G40(N1) or possibly A-1(O2'), which would be followed by proton transfer from G40(N1) to A-1(O2'). After this initial deprotonation, A-1(O2') starts attacking the phosphate as a hydroxyl group, which is hydrogen-bonded to deprotonated G40, concurrent with G40(N1) moving closer to the hydroxyl group and directing the in-line attack. Proton transfer from A-1(O2') to G40 is concomitant with attack of the scissile phosphate, followed by the remainder of the cleavage reaction. A mechanism in which an external base does not participate, but rather the proton transfers from A-1(O2') to a nonbridging oxygen during nucleophilic attack, was also considered but deemed to be less likely due to its higher effective free energy barrier. The calculated rate constant for the favored mechanism is in agreement with the experimental rate constant measured at biological Mg(2+) ion concentration. According to these calculations, catalysis is optimal when G40 has an elevated pKa rather than a pKa shifted toward neutrality, although a balance among the pKa's of A-1, G40, and the nonbridging oxygen is essential. These results have general implications, as the hammerhead, hairpin, and twister ribozymes have guanines at a similar position as G40.
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Affiliation(s)
- Sixue Zhang
- Department
of Chemistry, University of Illinois at
Urbana—Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United
States
| | - Abir Ganguly
- Department
of Chemistry, University of Illinois at
Urbana—Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United
States
| | - Puja Goyal
- Department
of Chemistry, University of Illinois at
Urbana—Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United
States
| | - Jamie
L. Bingaman
- Department
of Chemistry and Center for RNA Molecular Biology, Pennsylvania State University, 104 Chemistry Building, University Park, Pennsylvania 16802, United States
| | - Philip C. Bevilacqua
- Department
of Chemistry and Center for RNA Molecular Biology, Pennsylvania State University, 104 Chemistry Building, University Park, Pennsylvania 16802, United States
| | - Sharon Hammes-Schiffer
- Department
of Chemistry, University of Illinois at
Urbana—Champaign, 600 South Mathews Avenue, Urbana, Illinois 61801, United
States
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19
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Li Y, Wang C, Hao J, Cheng M, Jia G, Li C. Higher-order human telomeric G-quadruplex DNA metalloenzyme catalyzed Diels–Alder reaction: an unexpected inversion of enantioselectivity modulated by K+ and NH4+ ions. Chem Commun (Camb) 2015; 51:13174-7. [DOI: 10.1039/c5cc05215g] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
K+ and NH4+, bearing approximately equal ionic radius, present different allosteric activation for higher-order human telomeric G-quadruplex DNA metalloenzyme.
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Affiliation(s)
- Yinghao Li
- State Key Laboratory of Catalysis
- Dalian Institute of Chemical Physics
- Chinese Academy of Sciences
- Dalian 116023
- China
| | - Changhao Wang
- State Key Laboratory of Catalysis
- Dalian Institute of Chemical Physics
- Chinese Academy of Sciences
- Dalian 116023
- China
| | - Jingya Hao
- State Key Laboratory of Catalysis
- Dalian Institute of Chemical Physics
- Chinese Academy of Sciences
- Dalian 116023
- China
| | - Mingpan Cheng
- State Key Laboratory of Catalysis
- Dalian Institute of Chemical Physics
- Chinese Academy of Sciences
- Dalian 116023
- China
| | - Guoqing Jia
- State Key Laboratory of Catalysis
- Dalian Institute of Chemical Physics
- Chinese Academy of Sciences
- Dalian 116023
- China
| | - Can Li
- State Key Laboratory of Catalysis
- Dalian Institute of Chemical Physics
- Chinese Academy of Sciences
- Dalian 116023
- China
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20
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Ramesh A, Winkler WC. Metabolite-binding ribozymes. BIOCHIMICA ET BIOPHYSICA ACTA-GENE REGULATORY MECHANISMS 2014; 1839:989-994. [PMID: 24769284 DOI: 10.1016/j.bbagrm.2014.04.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2014] [Revised: 04/08/2014] [Accepted: 04/13/2014] [Indexed: 12/22/2022]
Abstract
Catalysis in the biological context was largely thought to be a protein-based phenomenon until the discovery of RNA catalysts called ribozymes. These discoveries demonstrated that many RNA molecules exhibit remarkable structural and functional versatility. By virtue of these features, naturally occurring ribozymes have been found to be involved in catalyzing reactions for fundamentally important cellular processes such as translation and RNA processing. Another class of RNAs called riboswitches directly binds ligands to control downstream gene expression. Most riboswitches regulate downstream gene expression by controlling premature transcription termination or by affecting the efficiency of translation initiation. However, one riboswitch class couples ligand-sensing to ribozyme activity. Specifically, the glmS riboswitch is a nucleolytic ribozyme, whose self-cleavage activity is triggered by the binding of GlcN6P. The products of this self-cleavage reaction are then targeted by cellular RNases for rapid degradation, thereby reducing glmS expression under conditions of sufficient GlcN6P. Since the discovery of the glmS ribozyme, other metabolite-binding ribozymes have been identified. Together, these discoveries have expanded the general understanding of noncoding RNAs and provided insights that will assist future development of synthetic riboswitch-ribozymes. A very broad overview of natural and synthetic ribozymes is presented herein with an emphasis on the structure and function of the glmS ribozyme as a paradigm for metabolite-binding ribozymes that control gene expression. This article is part of a Special Issue entitled: Riboswitches.
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Affiliation(s)
- Arati Ramesh
- The University of Texas Southwestern Medical Center, Department of Biophysics, 6001 Forest Park Rd, Dallas, USA.
| | - Wade C Winkler
- The University of Maryland, Department of Cell Biology and Molecular Genetics, 3112 Biosciences Research Building, College Park, MD, USA.
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21
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Lau MWL, Ferré-D'Amaré AR. An in vitro evolved glmS ribozyme has the wild-type fold but loses coenzyme dependence. Nat Chem Biol 2013; 9:805-10. [PMID: 24096303 DOI: 10.1038/nchembio.1360] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 09/05/2013] [Indexed: 12/26/2022]
Abstract
Uniquely among known ribozymes, the glmS ribozyme-riboswitch requires a small-molecule coenzyme, glucosamine-6-phosphate (GlcN6P). Although consistent with its gene-regulatory function, the use of GlcN6P is unexpected because all of the other characterized self-cleaving ribozymes use RNA functional groups or divalent cations for catalysis. To determine what active site features make this ribozyme reliant on GlcN6P and to evaluate whether it might have evolved from a coenzyme-independent ancestor, we isolated a GlcN6P-independent variant through in vitro selection. Three active site mutations suffice to generate a highly reactive RNA that adopts the wild-type fold but uses divalent cations for catalysis and is insensitive to GlcN6P. Biochemical and crystallographic comparisons of wild-type and mutant ribozymes show that a handful of functional groups fine-tune the RNA to be either coenzyme or cation dependent. These results indicate that a few mutations can confer new biochemical activities on structured RNAs. Thus, families of structurally related ribozymes with divergent function may exist.
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Affiliation(s)
- Matthew W L Lau
- National Heart, Lung and Blood Institute, Bethesda, Maryland, USA
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22
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Soukup JK. The structural and functional uniqueness of the glmS ribozyme. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 120:173-93. [PMID: 24156944 DOI: 10.1016/b978-0-12-381286-5.00005-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The glmS bacterial ribozyme/riboswitch is found in a number of Gram-positive bacteria, many of which are human pathogens. Investigation of the structure and function of the glmS catalyst will aid in the development of artificial agonists/antagonists that might function as novel antibiotics. The glmS ribozyme is mechanistically unique in that it is the first RNA catalyst identified to require a coenzyme, glucosamine-6-phosphate, for RNA self-cleavage. In addition, it is the first riboswitch identified to utilize self-cleavage as a mode of genetic regulation in metabolism. Significant biochemical and biophysical data exist for the glmS ribozyme and aid in mechanistically understanding the importance of RNA and coenzyme structure to function in acid-base catalysis.
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Affiliation(s)
- Juliane K Soukup
- Department of Chemistry, Creighton University, Omaha, Nebraska, USA
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23
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Abstract
The glmS ribozyme is the first natural self-cleaving ribozyme known to require a cofactor. The d-glucosamine-6-phosphate (GlcN6P) cofactor has been proposed to serve as a general acid, but its role in the catalytic mechanism has not been established conclusively. We surveyed GlcN6P-like molecules for their ability to support self-cleavage of the glmS ribozyme and found a strong correlation between the pH dependence of the cleavage reaction and the intrinsic acidity of the cofactors. For cofactors with low binding affinities, the contribution to rate enhancement was proportional to their intrinsic acidity. This linear free-energy relationship between cofactor efficiency and acid dissociation constants is consistent with a mechanism in which the cofactors participate directly in the reaction as general acid-base catalysts. A high value for the Brønsted coefficient (β ~ 0.7) indicates that a significant amount of proton transfer has already occurred in the transition state. The glmS ribozyme is the first self-cleaving RNA to use an exogenous acid-base catalyst.
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Affiliation(s)
- Júlia Viladoms
- Department of Chemical Physiology, and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA
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24
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Synthesis and evaluation of glucosamine-6-phosphate analogues as activators of glmS riboswitch. Tetrahedron 2012. [DOI: 10.1016/j.tet.2012.09.015] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
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25
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Bowman JC, Lenz TK, Hud NV, Williams LD. Cations in charge: magnesium ions in RNA folding and catalysis. Curr Opin Struct Biol 2012; 22:262-72. [PMID: 22595008 DOI: 10.1016/j.sbi.2012.04.006] [Citation(s) in RCA: 139] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Revised: 04/24/2012] [Accepted: 04/24/2012] [Indexed: 12/22/2022]
Affiliation(s)
- Jessica C Bowman
- School of Chemistry and Biochemistry, Parker H. Petit Institute for Bioengineering and Bioscience, Center for Ribosomal Origins and Evolution, Georgia Institute of Technology, Atlanta, GA 30332-0400, United States
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26
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Viladoms J, Scott LG, Fedor MJ. An active-site guanine participates in glmS ribozyme catalysis in its protonated state. J Am Chem Soc 2011; 133:18388-96. [PMID: 21936556 DOI: 10.1021/ja207426j] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Active-site guanines that occupy similar positions have been proposed to serve as general base catalysts in hammerhead, hairpin, and glmS ribozymes, but no specific roles for these guanines have been demonstrated conclusively. Structural studies place G33(N1) of the glmS ribozyme of Bacillus anthracis within hydrogen-bonding distance of the 2'-OH nucleophile. Apparent pK(a) values determined from the pH dependence of cleavage kinetics for wild-type and mutant glmS ribozymes do not support a role for G33, or any other active-site guanine, in general base catalysis. Furthermore, discrepancies between apparent pK(a) values obtained from functional assays and microscopic pK(a) values obtained from pH-fluorescence profiles with ribozymes containing a fluorescent guanosine analogue, 8-azaguanosine, at position 33 suggest that the pH-dependent step in catalysis does not involve G33 deprotonation. These results point to an alternative model in which G33(N1) in its neutral, protonated form donates a hydrogen bond to stabilize the transition state.
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Affiliation(s)
- Júlia Viladoms
- Department of Chemical Physiology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, United States
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27
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Golden BL. Two distinct catalytic strategies in the hepatitis δ virus ribozyme cleavage reaction. Biochemistry 2011; 50:9424-33. [PMID: 22003985 DOI: 10.1021/bi201157t] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The hepatitis delta virus (HDV) ribozyme and related RNAs are widely dispersed in nature. This RNA is a small nucleolytic ribozyme that self-cleaves to generate products with a 2',3'-cyclic phosphate and a free 5'-hydroxyl. Although small ribozymes are dependent on divalent metal ions under biologically relevant buffer conditions, they function in the absence of divalent metal ions at high ionic strengths. This characteristic suggests that a functional group within the covalent structure of small ribozymes is facilitating catalysis. Structural and mechanistic analyses have demonstrated that the HDV ribozyme active site contains a cytosine with a perturbed pK(a) that serves as a general acid to protonate the leaving group. The reaction of the HDV ribozyme in monovalent cations alone never approaches the velocity of the Mg(2+)-dependent reaction, and there is significant biochemical evidence that a Mg(2+) ion participates directly in catalysis. A recent crystal structure of the HDV ribozyme revealed that there is a metal binding pocket in the HDV ribozyme active site. Modeling of the cleavage site into the structure suggested that this metal ion can interact directly with the scissile phosphate and the nucleophile. In this manner, the Mg(2+) ion can serve as a Lewis acid, facilitating deprotonation of the nucleophile and stabilizing the conformation of the cleavage site for in-line attack of the nucleophile at the scissile phosphate. This catalytic strategy had previously been observed only in much larger ribozymes. Thus, in contrast to most large and small ribozymes, the HDV ribozyme uses two distinct catalytic strategies in its cleavage reaction.
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Affiliation(s)
- Barbara L Golden
- Department of Biochemistry, Purdue University, West Lafayette, Indiana 47907-2063, United States.
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