1
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Fang Z, Pazienza LT, Zhang J, Tam CP, Szostak JW. Catalytic Metal Ion-Substrate Coordination during Nonenzymatic RNA Primer Extension. J Am Chem Soc 2024; 146:10632-10639. [PMID: 38579124 PMCID: PMC11027144 DOI: 10.1021/jacs.4c00323] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 02/22/2024] [Accepted: 03/22/2024] [Indexed: 04/07/2024]
Abstract
Nonenzymatic template-directed RNA copying requires catalysis by divalent metal ions. The primer extension reaction involves the attack of the primer 3'-hydroxyl on the adjacent phosphate of a 5'-5'-imidazolium-bridged dinucleotide substrate. However, the nature of the interaction of the catalytic metal ion with the reaction center remains unclear. To explore the coordination of the catalytic metal ion with the imidazolium-bridged dinucleotide substrate, we examined catalysis by oxophilic and thiophilic metal ions with both diastereomers of phosphorothioate-modified substrates. We show that Mg2+ and Cd2+ exhibit opposite preferences for the two phosphorothioate substrate diastereomers, indicating a stereospecific interaction of the divalent cation with one of the nonbridging phosphorus substituents. High-resolution X-ray crystal structures of the products of primer extension with phosphorothioate substrates reveal the absolute stereochemistry of this interaction and indicate that catalysis by Mg2+ involves inner-sphere coordination with the nonbridging phosphate oxygen in the pro-SP position, while thiophilic cadmium ions interact with sulfur in the same position, as in one of the two phosphorothioate substrates. These results collectively suggest that during nonenzymatic RNA primer extension with a 5'-5'-imidazolium-bridged dinucleotide substrate the interaction of the catalytic Mg2+ ion with the pro-SP oxygen of the reactive phosphate plays a crucial role in the metal-catalyzed SN2(P) reaction.
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Affiliation(s)
- Ziyuan Fang
- Department
of Chemistry, Howard Hughes Medical Institute,
The University of Chicago, Chicago, Illinois 60637, United States
| | - Lydia T. Pazienza
- Department
of Chemistry and Chemical Biology, Harvard
University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
- Department
of Molecular Biology and Center for Computational and Integrative
Biology, Howard Hughes Medical Institute,
Massachusetts General Hospital, 185 Cambridge Street, Boston, Massachusetts 02114, United States
| | - Jian Zhang
- Department
of Chemistry, Howard Hughes Medical Institute,
The University of Chicago, Chicago, Illinois 60637, United States
| | - Chun Pong Tam
- Department
of Chemistry and Chemical Biology, Harvard
University, 12 Oxford Street, Cambridge, Massachusetts 02138, United States
- Department
of Molecular Biology and Center for Computational and Integrative
Biology, Howard Hughes Medical Institute,
Massachusetts General Hospital, 185 Cambridge Street, Boston, Massachusetts 02114, United States
| | - Jack W. Szostak
- Department
of Chemistry, Howard Hughes Medical Institute,
The University of Chicago, Chicago, Illinois 60637, United States
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2
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Kührová P, Mlýnský V, Otyepka M, Šponer J, Banáš P. Sensitivity of the RNA Structure to Ion Conditions as Probed by Molecular Dynamics Simulations of Common Canonical RNA Duplexes. J Chem Inf Model 2023; 63:2133-2146. [PMID: 36989143 PMCID: PMC10091408 DOI: 10.1021/acs.jcim.2c01438] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Indexed: 03/30/2023]
Abstract
RNA molecules play a key role in countless biochemical processes. RNA interactions, which are of highly diverse nature, are determined by the fact that RNA is a highly negatively charged polyelectrolyte, which leads to intimate interactions with an ion atmosphere. Although RNA molecules are formally single-stranded, canonical (Watson-Crick) duplexes are key components of folded RNAs. A double-stranded (ds) RNA is also important for the design of RNA-based nanostructures and assemblies. Despite the fact that the description of canonical dsRNA is considered the least problematic part of RNA modeling, the imperfect shape and flexibility of dsRNA can lead to imbalances in the simulations of larger RNAs and RNA-containing assemblies. We present a comprehensive set of molecular dynamics (MD) simulations of four canonical A-RNA duplexes. Our focus was directed toward the characterization of the influence of varying ion concentrations and of the size of the solvation box. We compared several water models and four RNA force fields. The simulations showed that the A-RNA shape was most sensitive to the RNA force field, with some force fields leading to a reduced inclination of the A-RNA duplexes. The ions and water models played a minor role. The effect of the box size was negligible, and even boxes with a small fraction of the bulk solvent outside the RNA hydration sphere were sufficient for the simulation of the dsRNA.
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Affiliation(s)
- Petra Kührová
- Regional
Centre of Advanced Technologies and Materials, Czech Advanced Technology
and Research Institute (CATRIN), Palacký
University Olomouc, Šlechtitelů 27, 779 00 Olomouc, Czech Republic
- Institute
of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 00 Brno, Czech Republic
| | - Vojtěch Mlýnský
- Institute
of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 00 Brno, Czech Republic
| | - Michal Otyepka
- Regional
Centre of Advanced Technologies and Materials, Czech Advanced Technology
and Research Institute (CATRIN), Palacký
University Olomouc, Šlechtitelů 27, 779 00 Olomouc, Czech Republic
- IT4Innovations, VSB − Technical University of Ostrava, 17. listopadu 2172/15, 708 00 Ostrava, Poruba, Czech Republic
| | - Jiří Šponer
- Regional
Centre of Advanced Technologies and Materials, Czech Advanced Technology
and Research Institute (CATRIN), Palacký
University Olomouc, Šlechtitelů 27, 779 00 Olomouc, Czech Republic
- Institute
of Biophysics of the Czech Academy of Sciences, Královopolská 135, 612 00 Brno, Czech Republic
| | - Pavel Banáš
- Regional
Centre of Advanced Technologies and Materials, Czech Advanced Technology
and Research Institute (CATRIN), Palacký
University Olomouc, Šlechtitelů 27, 779 00 Olomouc, Czech Republic
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3
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Hunsicker-Wang LM, Vogt MJ, Hoogstraten CG, Cosper NJ, Davenport AM, Hendon CH, Scott RA, Britt RD, DeRose VJ. Spectroscopic characterization of Mn2+ and Cd2+ coordination to phosphorothioates in the conserved A9 metal site of the hammerhead ribozyme. J Inorg Biochem 2022; 230:111754. [DOI: 10.1016/j.jinorgbio.2022.111754] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 01/28/2022] [Accepted: 02/04/2022] [Indexed: 11/25/2022]
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4
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Paramagnetic resonance investigation of mono- and di-manganese-containing systems in biochemistry. Methods Enzymol 2022; 666:315-372. [DOI: 10.1016/bs.mie.2022.02.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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5
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Mercury(II)-Catalyzed Cleavage, Isomerization and Depurination of RNA and DNA Model Compounds and Desulfurization of Their Phosphoromonothioate Analogs. Catalysts 2020. [DOI: 10.3390/catal10020219] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The potential of Hg(II), a metal ion so-far overlooked in the development of artificial nucleases, to cleave RNA and DNA has been assessed. Accordingly, Hg(II)-promoted cleavage and isomerization of the RNA model compound adenylyl-3′,5′-(2′,3′-O-methyleneadenosine) and depurination of 2′-deoxyadenosine were followed by HPLC as a function of pH (5.0–6.0) and the desulfurization of both diastereomers of the phosphoromonothioate analog of adenylyl-3′,5′-(2′,3′-O-methyleneadenosine) at a single pH (6.9). At 5 mM [Hg(II)], cleavage of the RNA model compound was accelerated by two orders of magnitude at the low and by one order of magnitude at the high end of the pH range. Between 0 and 5 mM [Hg(II)], the cleavage rate showed a sigmoidal dependence on [Hg(II)], suggesting the participation of more than one Hg(II) in the reaction. Isomerization and depurination were also facilitated by Hg(II), but much more modestly than cleavage, less than 2-fold over the entire pH range studied. Phosphoromonothioate desulfurization was by far the most susceptible reaction to Hg(II) catalysis, being accelerated by more than four orders of magnitude.
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6
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Cepeda-Plaza M, Peracchi A. Insights into DNA catalysis from structural and functional studies of the 8-17 DNAzyme. Org Biomol Chem 2020; 18:1697-1709. [DOI: 10.1039/c9ob02453k] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The review examines functional knowledge gathered over two decades of research on the 8-17 DNAzyme, focusing on three aspects: the structural requirements for catalysis, the role of metal ions and the participation of general acid-base catalysis.
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Affiliation(s)
| | - Alessio Peracchi
- Department of Chemistry
- Life Sciences and Environmental Sustainability
- University of Parma
- Parma
- Italy
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7
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Decoding on the ribosome depends on the structure of the mRNA phosphodiester backbone. Proc Natl Acad Sci U S A 2018; 115:E6731-E6740. [PMID: 29967153 DOI: 10.1073/pnas.1721431115] [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: 01/05/2023] Open
Abstract
During translation, the ribosome plays an active role in ensuring that mRNA is decoded accurately and rapidly. Recently, biochemical studies have also implicated certain accessory factors in maintaining decoding accuracy. However, it is currently unclear whether the mRNA itself plays an active role in the process beyond its ability to base pair with the tRNA. Structural studies revealed that the mRNA kinks at the interface of the P and A sites. A magnesium ion appears to stabilize this structure through electrostatic interactions with the phosphodiester backbone of the mRNA. Here we examined the role of the kink structure on decoding using a well-defined in vitro translation system. Disruption of the kink structure through site-specific phosphorothioate modification resulted in an acute hyperaccurate phenotype. We measured rates of peptidyl transfer for near-cognate tRNAs that were severely diminished and in some instances were almost 100-fold slower than unmodified mRNAs. In contrast to peptidyl transfer, the modifications had little effect on GTP hydrolysis by elongation factor thermal unstable (EF-Tu), suggesting that only the proofreading phase of tRNA selection depends critically on the kink structure. Although the modifications appear to have no effect on typical cognate interactions, peptidyl transfer for a tRNA that uses atypical base pairing is compromised. These observations suggest that the kink structure is important for decoding in the absence of Watson-Crick or G-U wobble base pairing at the third position. Our findings provide evidence for a previously unappreciated role for the mRNA backbone in ensuring uniform decoding of the genetic code.
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8
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Mikkola S, Lönnberg T, Lönnberg H. Phosphodiester models for cleavage of nucleic acids. Beilstein J Org Chem 2018; 14:803-837. [PMID: 29719577 PMCID: PMC5905247 DOI: 10.3762/bjoc.14.68] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2017] [Accepted: 03/12/2018] [Indexed: 12/12/2022] Open
Abstract
Nucleic acids that store and transfer biological information are polymeric diesters of phosphoric acid. Cleavage of the phosphodiester linkages by protein enzymes, nucleases, is one of the underlying biological processes. The remarkable catalytic efficiency of nucleases, together with the ability of ribonucleic acids to serve sometimes as nucleases, has made the cleavage of phosphodiesters a subject of intensive mechanistic studies. In addition to studies of nucleases by pH-rate dependency, X-ray crystallography, amino acid/nucleotide substitution and computational approaches, experimental and theoretical studies with small molecular model compounds still play a role. With small molecules, the importance of various elementary processes, such as proton transfer and metal ion binding, for stabilization of transition states may be elucidated and systematic variation of the basicity of the entering or departing nucleophile enables determination of the position of the transition state on the reaction coordinate. Such data is important on analyzing enzyme mechanisms based on synergistic participation of several catalytic entities. Many nucleases are metalloenzymes and small molecular models offer an excellent tool to construct models for their catalytic centers. The present review tends to be an up to date summary of what has been achieved by mechanistic studies with small molecular phosphodiesters.
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Affiliation(s)
- Satu Mikkola
- Department of Chemistry, University of Turku, FIN-20014 Turku, Finland
| | - Tuomas Lönnberg
- Department of Chemistry, University of Turku, FIN-20014 Turku, Finland
| | - Harri Lönnberg
- Department of Chemistry, University of Turku, FIN-20014 Turku, Finland
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9
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Cepeda-Plaza M, McGhee CE, Lu Y. Evidence of a General Acid-Base Catalysis Mechanism in the 8-17 DNAzyme. Biochemistry 2018; 57:1517-1522. [PMID: 29389111 PMCID: PMC5879137 DOI: 10.1021/acs.biochem.7b01096] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
DNAzymes are catalytic DNA molecules that can perform a variety of reactions. Although advances have been made in obtaining DNAzymes via in vitro selection and many of them have been developed into sensors and imaging agents for metal ions, bacteria, and other molecules, the structural features responsible for these enzymatic reactions are still not well understood. Previous studies of the 8-17 DNAzyme have suggested conserved guanines close to the phosphodiester transfer site may play a role in the catalytic reaction. To identify the specific guanine and functional group of the guanine responsible for the reaction, we herein report the effects of replacing G1.1 and G14 (G; p Ka,N1 = 9.4) with analogues with a different p Ka at the N1 position, such as inosine (G14I; p Ka,N1 = 8.7), 2,6-diaminopurine (G14diAP; p Ka,N1 = 5.6), and 2-aminopurine (G14AP; p Ka,N1 = 3.8) on pH-dependent reaction rates. A comparison of the pH dependence of the reaction rates of these DNAzymes demonstrated that G14 in the bulge loop next to the cleavage site, is involved in proton transfer at the catalytic site. In contrast, we did not find any evidence of G1.1 being involved in acid-base catalysis. These results support general acid-base catalysis as a feasible strategy used in DNA catalysis, as in RNA and protein enzymes.
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Affiliation(s)
- Marjorie Cepeda-Plaza
- Department of Chemical Sciences, School of Exact Sciences, Universidad Andres Bello, República 275, Santiago, Chile
| | - Claire E. McGhee
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, Illinois 61801
| | - Yi Lu
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave., Urbana, Illinois 61801
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10
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Specific phosphorothioate substitution within domain 6 of a group II intron ribozyme leads to changes in local structure and metal ion binding. J Biol Inorg Chem 2017; 23:167-177. [DOI: 10.1007/s00775-017-1519-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 11/14/2017] [Indexed: 10/18/2022]
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11
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Liu X, Chen Y, Fierke CA. Inner-Sphere Coordination of Divalent Metal Ion with Nucleobase in Catalytic RNA. J Am Chem Soc 2017; 139:17457-17463. [PMID: 29116782 PMCID: PMC6020041 DOI: 10.1021/jacs.7b08755] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Identification of the function of metal ions and the RNA moieties, particularly nucleobases, that bind metal ions is important in RNA catalysis. Here we combine single-atom and abasic substitutions to probe functions of conserved nucleobases in ribonuclease P (RNase P). Structural and biophysical studies of bacterial RNase P propose direct coordination of metal ions by the nucleobases of conserved uridine and guanosine in helix P4 of the RNA subunit (P RNA). To biochemically probe the function of metal ion interactions, we substituted the universally conserved bulged uridine (U51) in the P4 helix of circularly permuted Bacillus subtilis P RNA with 4-thiouridine, 4-deoxyuridine, and abasic modifications and G378/379 with 2-aminopurine, N7-deazaguanosine, and 6-thioguanosine. The functional group modifications of U51 decrease RNase P-catalyzed phosphodiester bond cleavage 16- to 23-fold, as measured by the single-turnover cleavage rate constant. The activity of the 4-thiouridine RNase P is partially rescued by addition of Cd(II) or Mn(II) ions. This is the first time a metal-rescue experiment provides evidence for inner-sphere divalent metal ion coordination with a nucleobase. Modifications of G379 modestly decrease the cleavage activity of RNase P, suggesting outer-sphere coordination of O6 on G379 to a metal ion. These data provide biochemical evidence for catalytically important interactions of the P4 helix of P RNA with metal ions, demonstrating that the bulged uridine coordinates at least one catalytic metal ion through an inner-sphere interaction. The combination of single-atom and abasic nucleotide substitutions provides a powerful strategy to probe functions of conserved nucleobases in large RNAs.
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Affiliation(s)
- Xin Liu
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Yu Chen
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Carol A. Fierke
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA
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12
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Jennings S, Chenevert M, Liu L, Mottamal M, Wojcik EJ, Huckaba TM. Characterization of kinesin switch I mutations that cause hereditary spastic paraplegia. PLoS One 2017; 12:e0180353. [PMID: 28678816 PMCID: PMC5498027 DOI: 10.1371/journal.pone.0180353] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2017] [Accepted: 06/14/2017] [Indexed: 11/18/2022] Open
Abstract
Kif5A is a neuronally-enriched isoform of the Kinesin-1 family of cellular transport motors. 23 separate mutations in the motor domain of Kif5A have been identified in patients with the complicated form of hereditary spastic paraplegia (HSP). We performed in vitro assays on dimeric recombinant Kif5A with HSP-causing mutations in the Switch I domain, which participates in the coordination and hydrolysis of ATP by kinesin. We observed a variety of significantly reduced catalytic and mechanical activities as a result of each mutation, with the shared phenotype from each that motility was significantly reduced. Substitution of Mn2+ for Mg2+ in our reaction buffers provides a dose-dependent rescue in both the catalytic and ensemble mechanical properties of the S203C mutant. This work provides mechanistic insight into the cause of HSP in patients with these mutations and points to future experiments to further dissect the root cause of this disease.
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Affiliation(s)
- Scott Jennings
- Department of Biology, Xavier University of Louisiana, New Orleans, Louisiana, United States of America
| | - Madeline Chenevert
- Department of Biology, Xavier University of Louisiana, New Orleans, Louisiana, United States of America
| | - Liqiong Liu
- Department of Biochemistry and Molecular Biology, LSU School of Medicine & Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Madhusoodanan Mottamal
- RCMI Molecular Modeling Core, Xavier University of Louisiana, New Orleans, Louisiana, United States of America
| | - Edward J. Wojcik
- Department of Biochemistry and Molecular Biology, LSU School of Medicine & Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Thomas M. Huckaba
- Department of Biology, Xavier University of Louisiana, New Orleans, Louisiana, United States of America
- * E-mail:
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13
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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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14
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Sushko ML, Thomas DG, Pabit SA, Pollack L, Onufriev AV, Baker NA. The Role of Correlation and Solvation in Ion Interactions with B-DNA. Biophys J 2016; 110:315-326. [PMID: 26789755 DOI: 10.1016/j.bpj.2015.12.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Revised: 11/30/2015] [Accepted: 12/07/2015] [Indexed: 01/28/2023] Open
Abstract
The ionic atmospheres around nucleic acids play important roles in biological function. Large-scale explicit solvent simulations coupled to experimental assays such as anomalous small-angle x-ray scattering can provide important insights into the structure and energetics of such atmospheres but are time- and resource intensive. In this article, we use classical density functional theory to explore the balance among ion-DNA, ion-water, and ion-ion interactions in ionic atmospheres of RbCl, SrCl2, and CoHexCl3 (cobalt hexamine chloride) around a B-form DNA molecule. The accuracy of the classical density functional theory calculations was assessed by comparison between simulated and experimental anomalous small-angle x-ray scattering curves, demonstrating that an accurate model should take into account ion-ion correlation and ion hydration forces, DNA topology, and the discrete distribution of charges on the DNA backbone. As expected, these calculations revealed significant differences among monovalent, divalent, and trivalent cation distributions around DNA. Approximately half of the DNA-bound Rb(+) ions penetrate into the minor groove of the DNA and half adsorb on the DNA backbone. The fraction of cations in the minor groove decreases for the larger Sr(2+) ions and becomes zero for CoHex(3+) ions, which all adsorb on the DNA backbone. The distribution of CoHex(3+) ions is mainly determined by Coulomb and steric interactions, while ion-correlation forces play a central role in the monovalent Rb(+) distribution and a combination of ion-correlation and hydration forces affect the Sr(2+) distribution around DNA. This does not imply that correlations in CoHex solutions are weaker or stronger than for other ions. Steric inaccessibility of the grooves to large CoHex ions leads to their binding at the DNA surface. In this binding mode, first-order electrostatic interactions (Coulomb) dominate the overall binding energy as evidenced by low sensitivity of ionic distribution to the presence or absence of second-order electrostatic correlation interactions.
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Affiliation(s)
- Maria L Sushko
- Physical Sciences Division, Pacific Northwest National Laboratory, Richland, Washington
| | - Dennis G Thomas
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington
| | - Suzette A Pabit
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York
| | - Lois Pollack
- School of Applied and Engineering Physics, Cornell University, Ithaca, New York
| | - Alexey V Onufriev
- Department of Computer Science and Department of Physics, Virginia Tech, Blacksburg, Virginia
| | - Nathan A Baker
- Computational and Statistical Analytics Division, Pacific Northwest National Laboratory, Richland, Washington; Division of Applied Mathematics, Brown University, Providence, Rhode Island.
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15
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van Schie SNS, Sengupta RN, Herschlag D. Differential Assembly of Catalytic Interactions within the Conserved Active Sites of Two Ribozymes. PLoS One 2016; 11:e0160457. [PMID: 27501145 PMCID: PMC4976970 DOI: 10.1371/journal.pone.0160457] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2016] [Accepted: 07/19/2016] [Indexed: 11/18/2022] Open
Abstract
Molecular recognition is central to biology and a critical aspect of RNA function. Yet structured RNAs typically lack the preorganization needed for strong binding and precise positioning. A striking example is the group I ribozyme from Tetrahymena, which binds its guanosine substrate (G) orders of magnitude slower than diffusion. Binding of G is also thermodynamically coupled to binding of the oligonucleotide substrate (S) and further work has shown that the transition from E•G to E•S•G accompanies a conformational change that allows G to make the active site interactions required for catalysis. The group I ribozyme from Azoarcus has a similarly slow association rate but lacks the coupled binding observed for the Tetrahymena ribozyme. Here we test, using G analogs and metal ion rescue experiments, whether this absence of coupling arises from a higher degree of preorganization within the Azoarcus active site. Our results suggest that the Azoarcus ribozyme forms cognate catalytic metal ion interactions with G in the E•G complex, interactions that are absent in the Tetrahymena E•G complex. Thus, RNAs that share highly similar active site architectures and catalyze the same reactions can differ in the assembly of transition state interactions. More generally, an ability to readily access distinct local conformational states may have facilitated the evolutionary exploration needed to attain RNA machines that carry out complex, multi-step processes.
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Affiliation(s)
- Sabine N. S. van Schie
- Department of Biochemistry, Stanford University, Stanford, California, 94305, United States of America
- Leiden Institute of Chemistry, Leiden University, Leiden, 2333 CC, the Netherlands
| | - Raghuvir N. Sengupta
- Department of Biochemistry, Stanford University, Stanford, California, 94305, United States of America
| | - Daniel Herschlag
- Department of Biochemistry, Stanford University, Stanford, California, 94305, United States of America
- Departments of Chemical Engineering and Chemistry, Stanford University, Stanford, California, 94305, United States of America
- Stanford ChEM-H (Chemistry, Engineering, and Medicine for Human Health), Stanford University, Stanford, California, 94305, United States of America
- * E-mail:
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16
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Hwang K, Hosseinzadeh P, Lu Y. Biochemical and Biophysical Understanding of Metal Ion Selectivity of DNAzymes. Inorganica Chim Acta 2016; 452:12-24. [PMID: 27695134 DOI: 10.1016/j.ica.2016.04.017] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This review summarizes research into the metal-binding properties of catalytic DNAzymes, towards the goal of understanding the structural properties leading to metal ion specificity. Progress made and insight gained from a range of biochemical and biophysical techniques are covered, and promising directions for future investigations are discussed.
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Affiliation(s)
- Kevin Hwang
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Parisa Hosseinzadeh
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801
| | - Yi Lu
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801; Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801
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17
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Sengupta RN, Van Schie SNS, Giambaşu G, Dai Q, Yesselman JD, York D, Piccirilli JA, Herschlag D. An active site rearrangement within the Tetrahymena group I ribozyme releases nonproductive interactions and allows formation of catalytic interactions. RNA (NEW YORK, N.Y.) 2016; 22:32-48. [PMID: 26567314 PMCID: PMC4691833 DOI: 10.1261/rna.053710.115] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Accepted: 09/23/2015] [Indexed: 06/05/2023]
Abstract
Biological catalysis hinges on the precise structural integrity of an active site that binds and transforms its substrates and meeting this requirement presents a unique challenge for RNA enzymes. Functional RNAs, including ribozymes, fold into their active conformations within rugged energy landscapes that often contain misfolded conformers. Here we uncover and characterize one such "off-pathway" species within an active site after overall folding of the ribozyme is complete. The Tetrahymena group I ribozyme (E) catalyzes cleavage of an oligonucleotide substrate (S) by an exogenous guanosine (G) cofactor. We tested whether specific catalytic interactions with G are present in the preceding E•S•G and E•G ground-state complexes. We monitored interactions with G via the effects of 2'- and 3'-deoxy (-H) and -amino (-NH(2)) substitutions on G binding. These and prior results reveal that G is bound in an inactive configuration within E•G, with the nucleophilic 3'-OH making a nonproductive interaction with an active site metal ion termed MA and with the adjacent 2'-OH making no interaction. Upon S binding, a rearrangement occurs that allows both -OH groups to contact a different active site metal ion, termed M(C), to make what are likely to be their catalytic interactions. The reactive phosphoryl group on S promotes this change, presumably by repositioning the metal ions with respect to G. This conformational transition demonstrates local rearrangements within an otherwise folded RNA, underscoring RNA's difficulty in specifying a unique conformation and highlighting Nature's potential to use local transitions of RNA in complex function.
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Affiliation(s)
- Raghuvir N Sengupta
- Department of Biochemistry, Stanford University, Stanford, California 94305, USA
| | - Sabine N S Van Schie
- Department of Biochemistry, Stanford University, Stanford, California 94305, USA Leiden Institute of Chemistry, Leiden University, Leiden, 2333 CC, The Netherlands
| | - George Giambaşu
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Qing Dai
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, USA Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois 60637, USA
| | - Joseph D Yesselman
- Department of Biochemistry, Stanford University, Stanford, California 94305, USA
| | - Darrin York
- Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854, USA
| | - Joseph A Piccirilli
- Department of Chemistry, The University of Chicago, Chicago, Illinois 60637, USA Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois 60637, USA
| | - Daniel Herschlag
- Department of Biochemistry, Stanford University, Stanford, California 94305, USA Department of Chemical Engineering, Engineering, and Medicine for Human Health (ChEM-H), Stanford University, Stanford, California 94305, USA Department of Chemistry, Engineering, and Medicine for Human Health (ChEM-H), Stanford University, Stanford, California 94305, USA Department of Chemistry, Engineering, and Medicine for Human Health (ChEM-H), Stanford University, Stanford, California 94305, USA
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18
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Radak BK, Lee TS, Harris ME, York DM. Assessment of metal-assisted nucleophile activation in the hepatitis delta virus ribozyme from molecular simulation and 3D-RISM. RNA (NEW YORK, N.Y.) 2015; 21:1566-1577. [PMID: 26170378 PMCID: PMC4536318 DOI: 10.1261/rna.051466.115] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 05/26/2015] [Indexed: 06/04/2023]
Abstract
The hepatitis delta virus ribozyme is an efficient catalyst of RNA 2'-O-transphosphorylation and has emerged as a key experimental system for identifying and characterizing fundamental features of RNA catalysis. Recent structural and biochemical data have led to a proposed mechanistic model whereby an active site Mg(2+) ion facilitates deprotonation of the O2' nucleophile, and a protonated cytosine residue (C75) acts as an acid to donate a proton to the O5' leaving group as noted in a previous study. This model assumes that the active site Mg(2+) ion forms an inner-sphere coordination with the O2' nucleophile and a nonbridging oxygen of the scissile phosphate. These contacts, however, are not fully resolved in the crystal structure, and biochemical data are not able to unambiguously exclude other mechanistic models. In order to explore the feasibility of this model, we exhaustively mapped the free energy surfaces with different active site ion occupancies via quantum mechanical/molecular mechanical (QM/MM) simulations. We further incorporate a three-dimensional reference interaction site model for the solvated ion atmosphere that allows these calculations to consider not only the rate associated with the chemical steps, but also the probability of observing the system in the presumed active state with the Mg(2+) ion bound. The QM/MM results predict that a pathway involving metal-assisted nucleophile activation is feasible based on the rate-controlling transition state barrier departing from the presumed metal-bound active state. However, QM/MM results for a similar pathway in the absence of Mg(2+) are not consistent with experimental data, suggesting that a structural model in which the crystallographically determined Mg(2+) is simply replaced with Na(+) is likely incorrect. It should be emphasized, however, that these results hinge upon the assumption of the validity of the presumed Mg(2+)-bound starting state, which has not yet been definitively verified experimentally, nor explored in depth computationally. Thus, further experimental and theoretical study is needed such that a consensus view of the catalytic mechanism emerges.
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Affiliation(s)
- Brian K Radak
- Center for Integrative Proteomics Research and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854-8076, USA Department of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455-0431, USA
| | - Tai-Sung Lee
- Center for Integrative Proteomics Research and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854-8076, USA
| | - Michael E Harris
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106, USA
| | - Darrin M York
- Center for Integrative Proteomics Research and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey 08854-8076, USA
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19
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Kellerman DL, Simmons KS, Pedraza M, Piccirilli JA, York DM, Harris ME. Determination of hepatitis delta virus ribozyme N(-1) nucleobase and functional group specificity using internal competition kinetics. Anal Biochem 2015; 483:12-20. [PMID: 25937290 DOI: 10.1016/j.ab.2015.04.024] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2015] [Revised: 04/17/2015] [Accepted: 04/23/2015] [Indexed: 12/16/2022]
Abstract
Biological catalysis involves interactions distant from the site of chemistry that can position the substrate for reaction. Catalysis of RNA 2'-O-transphosphorylation by the hepatitis delta virus (HDV) ribozyme is sensitive to the identity of the N(-1) nucleotide flanking the reactive phosphoryl group. However, the interactions that affect the conformation of this position, and in turn the 2'O nucleophile, are unclear. Here, we describe the application of multiple substrate internal competition kinetic analyses to understand how the N(-1) nucleobase contributes to HDV catalysis and test the utility of this approach for RNA structure-function studies. Internal competition reactions containing all four substrate sequence variants at the N(-1) position in reactions using ribozyme active site mutations at A77 and A78 were used to test a proposed base-pairing interaction. Mutants A78U, A78G, and A79G retain significant catalytic activity but do not alter the specificity for the N(-1) nucleobase. Effects of nucleobase analog substitutions at N(-1) indicate that U is preferred due to the ability to donate an H-bond in the Watson-Crick face and avoid minor groove steric clash. The results provide information essential for evaluating models of the HDV active site and illustrate multiple substrate kinetic analyses as a practical approach for characterizing structure-function relationships in RNA reactions.
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Affiliation(s)
- Daniel L Kellerman
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Kandice S Simmons
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Mayra Pedraza
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Joseph A Piccirilli
- Department of Chemistry and Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637, USA
| | - Darrin M York
- Center for Integrative Proteomics Research, BioMaPS Institute for Quantitative Biology and Department of Chemistry and Chemical Biology, Rutgers University, Piscataway, NJ 08854, USA
| | - Michael E Harris
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA.
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20
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Weissman BP, Li NS, York D, Harris M, Piccirilli JA. Heavy atom labeled nucleotides for measurement of kinetic isotope effects. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2015; 1854:1737-45. [PMID: 25828952 DOI: 10.1016/j.bbapap.2015.03.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Revised: 03/06/2015] [Accepted: 03/18/2015] [Indexed: 02/01/2023]
Abstract
Experimental analysis of kinetic isotope effects represents an extremely powerful approach for gaining information about the transition state structure of complex reactions not available through other methodologies. The implementation of this approach to the study of nucleic acid chemistry requires the synthesis of nucleobases and nucleotides enriched for heavy isotopes at specific positions. In this review, we highlight current approaches to the synthesis of nucleic acids enriched site specifically for heavy oxygen and nitrogen and their application in heavy atom isotope effect studies. This article is part of a special issue titled: Enzyme Transition States from Theory and Experiment.
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Affiliation(s)
| | - Nan-Sheng Li
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA
| | - Darrin York
- Center for Integrative Proteomics Research, Biology at the Interface with the Mathematical and Physical Sciences (BioMaPS) Institute for Quantitative Biology, The State University of New Jersey, Piscataway, NJ, USA; Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, NJ, USA
| | - Michael Harris
- Department of Biochemistry, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Joseph A Piccirilli
- Department of Chemistry, University of Chicago, Chicago, IL, USA; Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA.
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21
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Thaplyal P, Ganguly A, Hammes-Schiffer S, Bevilacqua PC. Inverse thio effects in the hepatitis delta virus ribozyme reveal that the reaction pathway is controlled by metal ion charge density. Biochemistry 2015; 54:2160-75. [PMID: 25799319 PMCID: PMC4824481 DOI: 10.1021/acs.biochem.5b00190] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
![]()
The
hepatitis delta virus (HDV) ribozyme self-cleaves in the presence
of a wide range of monovalent and divalent ions. Prior theoretical
studies provided evidence that self-cleavage proceeds via a concerted
or stepwise pathway, with the outcome dictated by the valency of the
metal ion. In the present study, we measure stereospecific thio effects
at the nonbridging oxygens of the scissile phosphate under a wide
range of experimental conditions, including varying concentrations
of diverse monovalent and divalent ions, and combine these with quantum
mechanical/molecular mechanical (QM/MM) free energy simulations on
the stereospecific thio substrates. The RP substrate gives large normal thio effects in the presence of all
monovalent ions. The SP substrate also
gives normal or no thio effects, but only for smaller monovalent and
divalent cations, such as Li+, Mg2+, Ca2+, and Sr2+; in contrast, sizable inverse thio
effects are found for larger monovalent and divalent cations, including
Na+, K+, NH4+, and Ba2+. Proton inventories are found to be unity in the presence
of the larger monovalent and divalent ions, but two in the presence
of Mg2+. Additionally, rate–pH profiles are inverted
for the low charge density ions, and only imidazole plus ammonium
ions rescue an inactive C75Δ variant in the absence of Mg2+. Results from the thio effect experiments, rate–pH
profiles, proton inventories, and ammonium/imidazole rescue experiments,
combined with QM/MM free energy simulations, support a change in the
mechanism of HDV ribozyme self-cleavage from concerted and metal ion-stabilized
to stepwise and proton transfer-stabilized as the charge density of
the metal ion decreases.
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Affiliation(s)
- Pallavi Thaplyal
- †Department of Chemistry and Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Abir Ganguly
- ‡Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, United States
| | - Sharon Hammes-Schiffer
- ‡Department of Chemistry, University of Illinois at Urbana-Champaign, 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
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22
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Robbins TJ, Ziebarth JD, Wang Y. Comparison of monovalent and divalent ion distributions around a DNA duplex with molecular dynamics simulation and a Poisson-Boltzmann approach. Biopolymers 2014; 101:834-48. [PMID: 24443090 PMCID: PMC4102171 DOI: 10.1002/bip.22461] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Revised: 11/22/2013] [Accepted: 01/15/2014] [Indexed: 12/15/2022]
Abstract
The ion atmosphere created by monovalent (Na(+) ) or divalent (Mg(2+) ) cations surrounding a B-form DNA duplex were examined using atomistic molecular dynamics (MD) simulations and the nonlinear Poisson-Boltzmann (PB) equation. The ion distributions predicted by the two methods were compared using plots of radial and two-dimensional cation concentrations and by calculating the total number of cations and net solution charge surrounding the DNA. Na(+) ion distributions near the DNA were more diffuse in PB calculations than in corresponding MD simulations, with PB calculations predicting lower concentrations near DNA groove sites and phosphate groups and a higher concentration in the region between these locations. Other than this difference, the Na(+) distributions generated by the two methods largely agreed, as both predicted similar locations of high Na(+) concentration and nearly identical values of the number of cations and the net solution charge at all distances from the DNA. In contrast, there was greater disagreement between the two methods for Mg(2+) cation concentration profiles, as both the locations and magnitudes of peaks in Mg(2+) concentration were different. Despite experimental and simulation observations that Mg(2+) typically maintains its first solvation shell when interacting with nucleic acids, modeling Mg(2+) as an unsolvated ion during PB calculations improved the agreement of the Mg(2+) ion atmosphere predicted by the two methods and allowed for values of the number of bound ions and net solution charge surrounding the DNA from PB calculations that approached the values observed in MD simulations.
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23
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Ward WL, Plakos K, DeRose VJ. Nucleic acid catalysis: metals, nucleobases, and other cofactors. Chem Rev 2014; 114:4318-42. [PMID: 24730975 PMCID: PMC4002065 DOI: 10.1021/cr400476k] [Citation(s) in RCA: 139] [Impact Index Per Article: 13.9] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Indexed: 12/17/2022]
Affiliation(s)
- W. Luke Ward
- Department of Chemistry and Biochemistry and Institute of
Molecular Biology, University of Oregon, Eugene, Oregon 97403, United States
| | - Kory Plakos
- Department of Chemistry and Biochemistry and Institute of
Molecular Biology, University of Oregon, Eugene, Oregon 97403, United States
| | - Victoria J. DeRose
- Department of Chemistry and Biochemistry and Institute of
Molecular Biology, University of Oregon, Eugene, Oregon 97403, United States
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24
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Abstract
The spliceosome, an assembly of snRNAs and proteins, catalyzes the removal of introns from premessenger RNAs. A new study identifies specific phosphates in the U2-U6 snRNA complex that position two catalytic metals. Remarkably, these correspond precisely to metal-binding phosphates in a homologous structure of Group II self-splicing introns, long proposed to be the ribozyme progenitor of spliceosome.
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Affiliation(s)
- Hiten D Madhani
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA.
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25
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Abstract
RNA and DNA carry out diverse functions in biology including catalysis, splicing, gene regulation, and storage of genetic information. Interest has grown in understanding how nucleic acids perform such sophisticated functions given their limited molecular repertoire. RNA can fold into diverse shapes that often perturb pKa values and allow it to ionize appreciably under biological conditions, thereby extending its molecular diversity. The goal of this chapter is to enable experimental measurement of pKa's in RNA and DNA. A number of experimental methods for measuring pKa values in RNA and DNA have been developed over the last 10 years, including RNA cleavage kinetics; UV-, fluorescence-, and NMR-detected pH titrations; and Raman crystallography. We begin with general considerations for choosing a pKa assay and then describe experimental conditions, advantages, and disadvantages for these assays. Potential pitfalls in measuring a pKa are provided including the presence of apparent pKa's due to a kinetic pKa or coupled acid- and alkali-promoted RNA unfolding, as well as degradation of RNA, precipitation of metal hydroxides and poor baselines. Use of multiple data fitting procedures and the study of appropriate mutants are described as ways to avoid some of these pitfalls. Application of these experimental methods to RNA and DNA will increase the number of available nucleic acid pKa values in the literature, which should deepen insight into biology and provide benchmarks for pKa calculations. Future directions for measuring pKa's in nucleic acids are discussed.
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Affiliation(s)
- Pallavi Thaplyal
- Department of Chemistry and Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - Philip C Bevilacqua
- Department of Chemistry and Center for RNA Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania, USA.
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26
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Affiliation(s)
- Scott A Strobel
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520, USA
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27
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Fica SM, Tuttle N, Novak T, Li NS, Lu J, Koodathingal P, Dai Q, Staley JP, Piccirilli JA. RNA catalyses nuclear pre-mRNA splicing. Nature 2013; 503:229-34. [PMID: 24196718 PMCID: PMC4666680 DOI: 10.1038/nature12734] [Citation(s) in RCA: 252] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2013] [Accepted: 10/03/2013] [Indexed: 12/24/2022]
Abstract
In nuclear pre-messenger RNA splicing, introns are excised by the spliceosome, a multi-megadalton machine composed of both proteins and small nuclear RNAs (snRNAs). Over thirty years ago, following the discovery of self-splicing group II intron RNAs, the snRNAs were hypothesized to catalyze splicing. However, no definitive evidence for a role of either RNA or protein in catalysis by the spliceosome has been reported to date. By using metal rescue strategies, here we show that the U6 snRNA catalyzes both splicing reactions by positioning divalent metals that stabilize the leaving groups during each reaction. Strikingly, all of the U6 catalytic metal ligands we identified correspond to the ligands observed to position catalytic, divalent metals in crystal structures of a group II intron RNA. These findings indicate that group II introns and the spliceosome share common catalytic mechanisms, and likely common evolutionary origins. Our results demonstrate that RNA mediates catalysis within the spliceosome.
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Affiliation(s)
- Sebastian M Fica
- 1] Graduate Program in Cell and Molecular Biology, The University of Chicago, Chicago, Illinois 60637, USA [2] Department of Molecular Genetics and Cell Biology, Cummings Life Sciences Center, 920 East 58th Street, The University of Chicago, Chicago, Illinois 60637, USA [3]
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28
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Thaplyal P, Ganguly A, Golden BL, Hammes-Schiffer S, Bevilacqua PC. Thio effects and an unconventional metal ion rescue in the genomic hepatitis delta virus ribozyme. Biochemistry 2013; 52:6499-514. [PMID: 24001219 DOI: 10.1021/bi4000673] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Metal ion and nucleobase catalysis are important for ribozyme mechanism, but the extent to which they cooperate is unclear. A crystal structure of the hepatitis delta virus (HDV) ribozyme suggested that the pro-RP oxygen at the scissile phosphate directly coordinates a catalytic Mg(2+) ion and is within hydrogen bonding distance of the amine of the general acid C75. Prior studies of the genomic HDV ribozyme, however, showed neither a thio effect nor metal ion rescue using Mn(2+). Here, we combine experiment and theory to explore phosphorothioate substitutions at the scissile phosphate. We report significant thio effects at the scissile phosphate and metal ion rescue with Cd(2+). Reaction profiles with an SP-phosphorothioate substitution are indistinguishable from those of the unmodified substrate in the presence of Mg(2+) or Cd(2+), supporting the idea that the pro-SP oxygen does not coordinate metal ions. The RP-phosphorothioate substitution, however, exhibits biphasic kinetics, with the fast-reacting phase displaying a thio effect of up to 5-fold and the slow-reacting phase displaying a thio effect of ~1000-fold. Moreover, the fast- and slow-reacting phases give metal ion rescues in Cd(2+) of up to 10- and 330-fold, respectively. The metal ion rescues are unconventional in that they arise from Cd(2+) inhibiting the oxo substrate but not the RP substrate. This metal ion rescue suggests a direct interaction of the catalytic metal ion with the pro-RP oxygen, in line with experiments with the antigenomic HDV ribozyme. Experiments without divalent ions, with a double mutant that interferes with Mg(2+) binding, or with C75 deleted suggest that the pro-RP oxygen plays at most a redundant role in positioning C75. Quantum mechanical/molecular mechanical (QM/MM) studies indicate that the metal ion contributes to catalysis by interacting with both the pro-RP oxygen and the nucleophilic 2'-hydroxyl, supporting the experimental findings.
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Affiliation(s)
- Pallavi Thaplyal
- Department of Chemistry and Center for RNA Molecular Biology, The Pennsylvania State University , University Park, Pennsylvania 16802, United States
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29
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Cochran JC, Thompson ME, Kull FJ. Metal switch-controlled myosin II from Dictyostelium discoideum supports closure of nucleotide pocket during ATP binding coupled to detachment from actin filaments. J Biol Chem 2013; 288:28312-23. [PMID: 23960071 DOI: 10.1074/jbc.m113.466045] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
G-proteins, kinesins, and myosins are hydrolases that utilize a common protein fold and divalent metal cofactor (typically Mg(2+)) to coordinate purine nucleotide hydrolysis. The nucleoside triphosphorylase activities of these enzymes are activated through allosteric communication between the nucleotide-binding site and the activator/effector/polymer interface to convert the free energy of nucleotide hydrolysis into molecular switching (G-proteins) or force generation (kinesins and myosin). We have investigated the ATPase mechanisms of wild-type and the S237C mutant of non-muscle myosin II motor from Dictyostelium discoideum. The S237C substitution occurs in the conserved metal-interacting switch-1, and we show that this substitution modulates the actomyosin interaction based on the divalent metal present in solution. Surprisingly, S237C shows rapid basal steady-state Mg(2+)- or Mn(2+)-ATPase kinetics, but upon binding actin, its MgATPase is inhibited. This actin inhibition is relieved by Mn(2+), providing a direct and experimentally reversible linkage of switch-1 and the actin-binding cleft through the swapping of divalent metals in the reaction. Using pyrenyl-labeled F-actin, we demonstrate that acto·S237C undergoes slow and weak MgATP binding, which limits the rate of steady-state catalysis. Mn(2+) rescues this effect to near wild-type activity. 2'(3')-O-(N-Methylanthraniloyl)-ADP release experiments show the need for switch-1 interaction with the metal cofactor for tight ADP binding. Our results are consistent with strong reciprocal coupling of nucleoside triphosphate and F-actin binding and provide additional evidence for the allosteric communication pathway between the nucleotide-binding site and the filament-binding region.
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Affiliation(s)
- Jared C Cochran
- From the Department of Molecular and Cellular Biochemistry, Indiana University, Bloomington, Indiana 47405
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30
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Javadi-Zarnaghi F, Höbartner C. Lanthanide cofactors accelerate DNA-catalyzed synthesis of branched RNA. J Am Chem Soc 2013; 135:12839-48. [PMID: 23895365 DOI: 10.1021/ja406162z] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Most deoxyribozymes (DNA catalysts) require metal ions as cofactors for catalytic activity, with Mg(2+), Mn(2+), and Zn(2+) being the most represented activators. Trivalent transition-metal ions have been less frequently considered. Rare earth ions offer attractive properties for studying metal ion binding by biochemical and spectroscopic methods. Here we report the effect of lanthanide cofactors, in particular terbium (Tb(3+)), for DNA-catalyzed synthesis of 2',5'-branched RNA. We found up to 10(4)-fold increased ligation rates for the 9F7 deoxribozyme using 100 μM Tb(3+) and 7 mM Mg(2+), compared to performing the reaction with 7 mM Mg(2+) alone. Combinatorial mutation interference analysis (CoMA) was used to identify nucleotides in the catalytic region of 9F7 that are essential for ligation activity with different metal ion combinations. A minimized version of the DNA enzyme sustained high levels of Tb(3+)-assisted activity. Sensitized luminescence of Tb(3+) bound to DNA in combination with DMS probing and DNase I footprinting results supported the CoMA data. The accelerating effect of Tb(3+) was confirmed for related RNA-ligating deoxyribozymes, pointing toward favorable activation of internal 2'-OH nucleophiles. The results of this study offer fundamental insights into nucleotide requirements for DNA-catalyzed RNA ligation and will be beneficial for practical applications that utilize 2',5'-branched RNA.
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Affiliation(s)
- Fatemeh Javadi-Zarnaghi
- Research Group Nucleic Acid Chemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany
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31
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Ding W, Deng W, Zhu H, Liang H. Metallo-toeholds: controlling DNA strand displacement driven by Hg(ii) ions. Chem Commun (Camb) 2013; 49:9953-5. [DOI: 10.1039/c3cc45373a] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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32
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Robbins TJ, Wang Y. Effect of initial ion positions on the interactions of monovalent and divalent ions with a DNA duplex as revealed with atomistic molecular dynamics simulations. J Biomol Struct Dyn 2012; 31:1311-23. [PMID: 23153112 DOI: 10.1080/07391102.2012.732344] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Monovalent (Na(+)) and divalent (Mg(2+)) ion distributions around the Dickerson-Drew dodecamer were studied by atomistic molecular dynamics (MD) simulations with AMBER molecular modeling software. Different initial placements of ions were tried and the resulting effects on the ion distributions around DNA were investigated. For monovalent ions, results were found to be nearly independent of initial cation coordinates. However, Mg(2+) ions demonstrated a strong initial coordinate dependent behavior. While some divalent ions initially placed near the DNA formed essentially permanent direct coordination complexes with electronegative DNA atoms, Mg(2+) ions initially placed further away from the duplex formed a full, nonexchanging, octahedral first solvation shell. These fully solvated cations were still capable of binding with DNA with events lasting up to 20 ns, and in comparison were bound much longer than Na(+) ions. Force field parameters were also investigated with modest and little differences arising from ion (ions94 and ions08) and nucleic acid description (ff99, ff99bsc0, and ff10), respectively. Based on known Mg(2+) ion solvation structure, we conclude that in most cases Mg(2+) ions retain their first solvation shell, making only solvent-mediated contacts with DNA duplex. The proper way to simulate Mg(2+) ions around DNA duplex, therefore, should begin with ions placed in the bulk water.
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Affiliation(s)
- Timothy J Robbins
- a Department of Chemistry , University of Memphis , Memphis , TN , 38152 , USA
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Li NS, Frederiksen JK, Piccirilli JA. Automated solid-phase synthesis of RNA oligonucleotides containing a nonbridging phosphorodithioate linkage via phosphorothioamidites. J Org Chem 2012; 77:9889-92. [PMID: 23050987 DOI: 10.1021/jo301834p] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
This work describes a general method for the synthesis of oligoribonucleotides containing a site-specific nonbridging phosphorodithioate linkage via automated solid-phase synthesis using 5'-O-DMTr-2'-O-TBS-ribonucleoside 3'-N,N-dimethyl-S-(2,4-dichlorobenzyl) phosphorothioamidites (2a-2d). The 3'-phosphorothioamidites (2a-2d) can be conveniently prepared in good yields (86-99%) via a one-pot reaction from the corresponding 5'-O-DMTr-2'-O-TBS-ribonucleosides (1a-1d).
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Affiliation(s)
- Nan-Sheng Li
- Department of Biochemistry & Molecular Biology, The University of Chicago, 929 East 57th Street, Chicago, Illinois 60637, United States.
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34
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RNA-Cleaving DNA Enzymes and Their Potential Therapeutic Applications as Antibacterial and Antiviral Agents. FROM NUCLEIC ACIDS SEQUENCES TO MOLECULAR MEDICINE 2012. [PMCID: PMC7119987 DOI: 10.1007/978-3-642-27426-8_15] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
DNA catalysts are synthetic single-stranded DNA molecules that have been identified by in vitro selection from random sequence DNA pools. The most prominent representatives of DNA catalysts (also known as DNA enzymes, deoxyribozymes, or DNAzymes) catalyze the site-specific cleavage of RNA substrates. Two distinct groups of RNA-cleaving DNA enzymes are the 10-23 and 8-17 enzymes. A typical RNA-cleaving DNA enzyme consists of a catalytic core and two short binding arms which form Watson–Crick base pairs with the RNA targets. RNA cleavage is usually achieved with the assistance of metal ions such as Mg2+, Ca2+, Mn2+, Pb2+, or Zn2+, but several chemically modified DNA enzymes can cleave RNA in the absence of divalent metal ions. A number of studies have shown the use of 10-23 DNA enzymes for modest downregulation of therapeutically relevant RNA targets in cultured cells and in whole mammals. Here we focus on mechanistic aspects of RNA-cleaving DNA enzymes and their potential to silence therapeutically appealing viral and bacterial gene targets. We also discuss delivery options and challenges involved in DNA enzyme-based therapeutic strategies.
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Parthier C, Görlich S, Jaenecke F, Breithaupt C, Bräuer U, Fandrich U, Clausnitzer D, Wehmeier UF, Böttcher C, Scheel D, Stubbs MT. The O-carbamoyltransferase TobZ catalyzes an ancient enzymatic reaction. Angew Chem Int Ed Engl 2012; 51:4046-52. [PMID: 22383337 DOI: 10.1002/anie.201108896] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2011] [Indexed: 11/09/2022]
Affiliation(s)
- Christoph Parthier
- Institut für Biochemie und Biotechnologie, Martin-Luther-Universität Halle-Wittenberg, Kurt-Mothes-Strasse 3, 06120 Halle (Saale), Germany
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36
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Parthier C, Görlich S, Jaenecke F, Breithaupt C, Bräuer U, Fandrich U, Clausnitzer D, Wehmeier UF, Böttcher C, Scheel D, Stubbs MT. Die O-Carbamoyltransferase TobZ katalysiert eine enzymatische Reaktion frühen Ursprungs. Angew Chem Int Ed Engl 2012. [DOI: 10.1002/ange.201108896] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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37
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Sgrignani J, Magistrato A. The structural role of Mg2+ ions in a class I RNA polymerase ribozyme: a molecular simulation study. J Phys Chem B 2012; 116:2259-68. [PMID: 22268599 DOI: 10.1021/jp206475d] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
According to the RNA world hypothesis, self-replicating ribozymes, storing the genetic information and being able to perform catalysis, were the constituents of the first living organisms. In particular, RNA polymerase ribozymes, similar to current proteinaceous enzymatic polymerases, may have been able to promote the synthesis of RNA strands in a primitive world. Polymerase catalysis is usually assisted by Mg(2+) ions, but it is not always trivial to find out experimentally the number of Mg(2+) ions placed in the active site as well as the identity and the number of their coordination ligands. Here, we addressed this issue in an artificial class I ligase ribozyme. On the basis of a recently solved crystal structure, we constructed computational models of reactant and product states of this ribozyme, considering monometallic and bimetallic species. Our models were relaxed by force field based molecular dynamics (MD) simulations and mixed quantum-classical (QM/MM) MD. The structural and dynamical properties of these models were consistent with experimental data and were validated by a comparison with the catalytic sites of proteinaceous DNA and RNA polymerases. Consistently with enzymatic polymerases, our results suggest that class I RNA ligases most probably contain two magnesium ions in the active site and they may, therefore, catalyze the junction of two RNA strands via "a two Mg(2+) ions" mechanism.
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Affiliation(s)
- Jacopo Sgrignani
- CNR-IOM-Democritos National Simulation Center C/o International Studies for Advanced Studies (SISSA/ISAS), Via Bonomea 265, 34165, Trieste, Italy
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Ward WL, DeRose VJ. Ground-state coordination of a catalytic metal to the scissile phosphate of a tertiary-stabilized Hammerhead ribozyme. RNA (NEW YORK, N.Y.) 2012; 18:16-23. [PMID: 22124015 PMCID: PMC3261738 DOI: 10.1261/rna.030239.111] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Accepted: 10/11/2011] [Indexed: 05/24/2023]
Abstract
Although the Hammerhead ribozyme (HHRz) has long been used as a model system in the field of ribozyme enzymology, several details of its mechanism are still not well understood. In particular, significant questions remain concerning the disposition and role of catalytic metals in the HHRz. Previous metal-rescue experiments using a "minimal" HHRz resulted in prediction of a catalytic metal that is bound in the A9/G10.1 site in the ground state of the reaction and that bridges to the scissile phosphate further along the reaction pathway. "Native" or extended HHRz constructs contain tertiary contacts that stabilize a more compact structure at moderate ionic strength. We performed Cd(2+) rescue experiments on an extended HHRz from Schistosoma mansoni using stereo-pure scissile phosphorothioate-substituted substrates in order to determine whether a metal ion makes contact with the scissile phosphate in the ground state or further along the reaction coordinate. Inhibition in Ca(2+)/Mg(2+) and rescue by thiophilic Cd(2+) was specific for the R(p)-S stereoisomer of the scissile phosphate. The affinity of the rescuing Cd(2+), measured in two different ionic strength backgrounds, increased fourfold to 17-fold when the pro-R(p) oxygen is replaced by sulfur. These data support a model in which the rescuing metal ion makes a ground-state interaction with the scissile phosphate in the native HHRz. The resulting model for Mg(2+) activation in the HHRz places a metal ion in contact with the scissile phosphate, where it may provide ground-state electrostatic activation of the substrate.
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Affiliation(s)
- W. Luke Ward
- Department of Chemistry, University of Oregon, Eugene, Oregon 97403-1253, USA
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403-1253, USA
| | - Victoria J. DeRose
- Department of Chemistry, University of Oregon, Eugene, Oregon 97403-1253, USA
- Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403-1253, USA
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Abstract
Metal ions are inextricably involved with nucleic acids due to their polyanionic nature. In order to understand the structure and function of RNAs and DNAs, one needs to have detailed pictures on the structural, thermodynamic, and kinetic properties of metal ion interactions with these biomacromolecules. In this review we first compile the physicochemical properties of metal ions found and used in combination with nucleic acids in solution. The main part then describes the various methods developed over the past decades to investigate metal ion binding by nucleic acids in solution. This includes for example hydrolytic and radical cleavage experiments, mutational approaches, as well as kinetic isotope effects. In addition, spectroscopic techniques like EPR, lanthanide(III) luminescence, IR and Raman as well as various NMR methods are summarized. Aside from gaining knowledge about the thermodynamic properties on the metal ion-nucleic acid interactions, especially NMR can be used to extract information on the kinetics of ligand exchange rates of the metal ions applied. The final section deals with the influence of anions, buffers, and the solvent permittivity on the binding equilibria between metal ions and nucleic acids. Little is known on some of these aspects, but it is clear that these three factors have a large influence on the interaction between metal ions and nucleic acids.
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Affiliation(s)
- Maria Pechlaner
- Institute of Inorganic Chemistry, University of Zürich, Zürich, Switzerland
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40
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Erat MC, Coles J, Finazzo C, Knobloch B, Sigel RK. Accurate analysis of Mg2+ binding to RNA: From classical methods to a novel iterative calculation procedure. Coord Chem Rev 2012. [DOI: 10.1016/j.ccr.2011.08.009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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41
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Cochran JC, Zhao YC, Wilcox DE, Kull FJ. A metal switch for controlling the activity of molecular motor proteins. Nat Struct Mol Biol 2011; 19:122-7. [PMID: 22198464 PMCID: PMC3252401 DOI: 10.1038/nsmb.2190] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2011] [Accepted: 10/21/2011] [Indexed: 11/30/2022]
Abstract
Kinesins are molecular motors that require a divalent metal ion (for example, Mg(2+)) to convert the energy of ATP hydrolysis into directed force production along microtubules. Here we present the crystal structure of a recombinant kinesin motor domain bound to Mn(2+) and ADP and report on a serine-to-cysteine substitution in the switch 1 motif of kinesin that allows its ATP hydrolysis activity to be controlled by adjusting the ratio of Mn(2+) to Mg(2+). This mutant kinesin binds ATP similarly in the presence of either metal ion, but its ATP hydrolysis activity is greatly diminished in the presence of Mg(2+). In human kinesin-1 and kinesin-5 as well as Drosophila melanogaster kinesin-10 and kinesin-14, this defect is rescued by Mn(2+), providing a way to control both the enzymatic activity and force-generating ability of these nanomachines.
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Affiliation(s)
- Jared C. Cochran
- Dartmouth College, Department of Chemistry, Hanover, New Hampshire 03755, USA
| | - Yu Cheng Zhao
- Dartmouth College, Department of Chemistry, Hanover, New Hampshire 03755, USA
| | - Dean E. Wilcox
- Dartmouth College, Department of Chemistry, Hanover, New Hampshire 03755, USA
| | - F. Jon Kull
- Dartmouth College, Department of Chemistry, Hanover, New Hampshire 03755, USA
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42
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Wilcox JL, Ahluwalia AK, Bevilacqua PC. Charged nucleobases and their potential for RNA catalysis. Acc Chem Res 2011; 44:1270-9. [PMID: 21732619 DOI: 10.1021/ar2000452] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Catalysis in living cells is carried out by both proteins and RNA. Protein enzymes have been known for over 200 years, but RNA enzymes, or "ribozymes", were discovered only 30 years ago. Developing insight into RNA enzyme mechanisms is invaluable for better understanding both extant biological catalysis as well as the primitive catalysis envisioned in an early RNA-catalyzed life. Natural ribozymes include large RNAs such as the group I and II introns; small RNAs such as the hepatitis delta virus and the hairpin, hammerhead, VS, and glmS ribozymes; and the RNA portion of the ribosome and spliceosome. RNA enzymes use many of the same catalytic strategies as protein enzymes, but do so with much simpler side chains. Among these strategies are metal ion, general acid-base, and electrostatic catalysis. In this Account, we examine evidence for participation of charged nucleobases in RNA catalysis. Our overall approach is to integrate direct measurements on catalytic RNAs with thermodynamic studies on oligonucleotide model systems. The charged amino acids make critical contributions to the mechanisms of nearly all protein enzymes. Ionized nucleobases should be critical for RNA catalysis as well. Indeed, charged nucleobases have been implicated in RNA catalysis as general acid-bases and oxyanion holes. We provide an overview of ribozyme studies involving nucleobase catalysis and the complications involved in developing these mechanisms. We also consider driving forces for perturbation of the pK(a) values of the bases. Mechanisms for pK(a) values shifting toward neutrality involve electrostatic stabilization and the addition of hydrogen bonding. Both mechanisms couple protonation with RNA folding, which we treat with a thermodynamic formalism and conceptual models. Furthermore, ribozyme reaction mechanisms can be multichannel, which demonstrates the versatility of ribozymes but makes analysis of experimental data challenging. We examine advances in measuring and analyzing perturbed pK(a) values in RNA. Raman crystallography and fluorescence spectroscopy have been especially important for pK(a) measurement. These methods reveal pK(a) values for the nucleobases A or C equal to or greater than neutrality, conferring potential histidine- and lysine/arginine-like behavior on them. Structural support for ionization of the nucleobases also exists: an analysis of RNA structures in the databases conducted herein suggests that charging of the bases is neither especially uncommon nor difficult to achieve under cellular conditions. Our major conclusions are that cationic and anionic charge states of the nucleobases occur in RNA enzymes and that these states make important catalytic contributions to ribozyme activity. We conclude by considering outstanding questions and possible experimental and theoretical approaches for further advances.
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Affiliation(s)
- Jennifer L. Wilcox
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Amarpreet K. Ahluwalia
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
| | - Philip C. Bevilacqua
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States
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43
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Wachowius F, Höbartner C. Probing essential nucleobase functional groups in aptamers and deoxyribozymes by nucleotide analogue interference mapping of DNA. J Am Chem Soc 2011; 133:14888-91. [PMID: 21863810 DOI: 10.1021/ja205894w] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nucleotide analogue interference mapping of DNA (dNAIM) is here introduced as a new nonenzymatic interference-based approach that enables high-throughput identification of essential nucleobase functional groups in DNA aptamers and in the catalytic core of deoxyribozymes. Nucleobase-modified ribonucleotides are statistically incorporated into DNA by solid-phase synthesis, employing the 2'-OH group as a chemical tag for analysis of interference effects. This method is exemplified on an AMP-binding DNA aptamer and was further used to identify indispensable nucleobase functional groups for DNA-catalyzed RNA-ligation by the Mg(2+)-dependent deoxyribozymes 7S11 and 9DB1. dNAIM should prove broadly useful for facile structural probing of functional DNA for which active and inactive variants can be separated based on catalytic or ligand-binding activities.
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Affiliation(s)
- Falk Wachowius
- Research Group Nucleic Acid Chemistry, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
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44
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Torigoe H, Miyakawa Y, Ono A, Kozasa T. Thermodynamic properties of the specific binding between Ag+ ions and C:C mismatched base pairs in duplex DNA. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2011; 30:149-67. [PMID: 21360412 DOI: 10.1080/15257770.2011.553210] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Metal-mediated base pairs formed by the interaction between metal ions and artificial bases in oligonucleotides have been developed for potential applications in nanotechnology. We recently found that a natural C:C mismatched base pair bound to an Ag(+) ion to generate a novel metal-mediated base pair in duplex DNA. Preparation of the novel C-Ag-C base pair involving natural bases is more convenient than that of metal-mediated base pairs involving artificial bases because time-consuming base synthesis is not required. Here, we examined the thermodynamic properties of the binding between the Ag(+) ion and each of single and double C:C mismatched base pair in duplex DNA by isothermal titration calorimetry. The Ag(+) ion specifically bound to the C:C mismatched base pair at a 1:1 molar ratio with 10(6) M(-1) binding constant, which was significantly larger than those for nonspecific metal ion-DNA interactions. The specific binding between the Ag(+) ion and the single C:C mismatched base pair was mainly driven by the positive dehydration entropy change and the negative binding enthalpy change. In the interaction between the Ag(+) ion and each of the consecutive and interrupted double C:C mismatched base pairs, stoichiometric binding at a 1:1 molar ratio was achieved in each step of the first and second Ag(+) binding. The binding affinity for the second Ag(+) binding was similar to that for the first Ag(+) binding. Stoichiometric binding without interference and negative cooperativity may be favorable for aligning multiple Ag(+) ions in duplex DNA for applications of the metal-mediated base pairs in nanotechnology.
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Affiliation(s)
- Hidetaka Torigoe
- Department of Applied Chemistry, Faculty of Science, Tokyo University of Science, Tokyo, Japan.
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45
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Shechner DM, Bartel DP. The structural basis of RNA-catalyzed RNA polymerization. Nat Struct Mol Biol 2011; 18:1036-42. [PMID: 21857665 PMCID: PMC3169305 DOI: 10.1038/nsmb.2107] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Accepted: 06/22/2011] [Indexed: 12/05/2022]
Abstract
Early life presumably required polymerase ribozymes capable of replicating RNA. Known polymerase ribozymes best approximating such replicases use as their catalytic engine an RNA-ligase ribozyme originally selected from random RNA sequences. Here, we report 3.15 Å crystal structures of this ligase trapped in catalytically viable pre-ligation states, with the 3′-hydroxyl nucleophile positioned for in-line attack on the 5′-triphosphate. Guided by metal and solvent-mediated interactions, the 5′-triphosphate hooks into the major groove of the adjoining RNA duplex in an unanticipated conformation. Two phosphates and the nucleophile jointly coordinate an active-site metal ion. Atomic mutagenesis experiments demonstrate that active-site nucleobase and hydroxyl groups also participate directly in catalysis, collectively playing a role that in proteinaceous polymerases is performed by a second metal ion. Thus artificial ribozymes can employ complex catalytic strategies that differ dramatically from those of analogous biological enzymes.
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Affiliation(s)
- David M Shechner
- Whitehead Institute for Biomedical Research, Cambridge, Massachusetts, USA
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46
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Lönnberg T. Understanding Catalysis of Phosphate‐Transfer Reactions by the Large Ribozymes. Chemistry 2011; 17:7140-53. [DOI: 10.1002/chem.201100009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Tuomas Lönnberg
- Department of Chemistry, University of Turku, Vatselankatu 2, 20140 Turku (Finland), Fax: (+358) 2‐333‐6700
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47
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Lee C, Jaladat Y, Mohammadi A, Sharifi A, Geisler S, Valadkhan S. Metal binding and substrate positioning by evolutionarily invariant U6 sequences in catalytically active protein-free snRNAs. RNA (NEW YORK, N.Y.) 2010; 16:2226-38. [PMID: 20826700 PMCID: PMC2957061 DOI: 10.1261/rna.2170910] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2010] [Accepted: 07/31/2010] [Indexed: 05/20/2023]
Abstract
We have previously shown that a base-paired complex formed by two of the spliceosomal RNA components, U6 and U2 small nuclear RNAs (snRNAs), can catalyze a two-step splicing reaction that depended on an evolutionarily invariant region in U6, the ACAGAGA box. Here we further analyze this RNA-catalyzed reaction and show that while the 5' and 3' splice site substrates are juxtaposed and positioned near the ACAGAGA sequence in U6, the role of the snRNAs in the reaction is beyond mere juxtaposition of the substrates and likely involves the formation of a sophisticated active site. Interestingly, the snRNA-catalyzed reaction is metal dependent, as is the case with other known splicing RNA enzymes, and terbium(III) cleavage reactions indicate metal binding by the U6/U2 complex within the evolutionarily conserved regions of U6. The above results, combined with the structural similarities between U6 and catalytically critical domains in group II self-splicing introns, suggest that the base-paired complex of U6 and U2 snRNAs is a vestigial ribozyme and a likely descendant of a group II-like self-splicing intron.
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Affiliation(s)
- Caroline Lee
- Center for RNA Molecular Biology, Case Western Reserve University, Cleveland, Ohio 44106, USA
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48
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Torigoe H, Ono A, Kozasa T. HgIIIon Specifically Binds with T:T Mismatched Base Pair in Duplex DNA. Chemistry 2010; 16:13218-25. [DOI: 10.1002/chem.201001171] [Citation(s) in RCA: 133] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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49
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Hsieh J, Koutmou KS, Rueda D, Koutmos M, Walter NG, Fierke CA. A divalent cation stabilizes the active conformation of the B. subtilis RNase P x pre-tRNA complex: a role for an inner-sphere metal ion in RNase P. J Mol Biol 2010; 400:38-51. [PMID: 20434461 PMCID: PMC2939038 DOI: 10.1016/j.jmb.2010.04.050] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2010] [Revised: 04/22/2010] [Accepted: 04/24/2010] [Indexed: 01/25/2023]
Abstract
Metal ions interact with RNA to enhance folding, stabilize structure, and, in some cases, facilitate catalysis. Assigning functional roles to specifically bound metal ions presents a major challenge in analyzing the catalytic mechanisms of ribozymes. Bacillus subtilis ribonuclease P (RNase P), composed of a catalytically active RNA subunit (PRNA) and a small protein subunit (P protein), catalyzes the 5'-end maturation of precursor tRNAs (pre-tRNAs). Inner-sphere coordination of divalent metal ions to PRNA is essential for catalytic activity but not for the formation of the RNase P x pre-tRNA (enzyme-substrate, ES) complex. Previous studies have demonstrated that this ES complex undergoes an essential conformational change (to the ES* conformer) before the cleavage step. Here, we show that the ES* conformer is stabilized by a high-affinity divalent cation capable of inner-sphere coordination, such as Ca(II) or Mg(II). Additionally, a second, lower-affinity Mg(II) activates cleavage catalyzed by RNase P. Structural changes that occur upon binding Ca(II) to the ES complex were determined by time-resolved Förster resonance energy transfer measurements of the distances between donor-acceptor fluorophores introduced at specific locations on the P protein and pre-tRNA 5' leader. These data demonstrate that the 5' leader of pre-tRNA moves 4 to 6 A closer to the PRNA x P protein interface during the ES-to-ES* transition and suggest that the metal-dependent conformational change reorganizes the bound substrate in the active site to form a catalytically competent ES* complex.
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Affiliation(s)
- John Hsieh
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan
| | | | - David Rueda
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan
| | - Markos Koutmos
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan
| | - Nils G. Walter
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan
| | - Carol A. Fierke
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan
- Department of Biological Chemistry, University of Michigan, Ann Arbor, Michigan
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50
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McClain WH, Lai LB, Gopalan V. Trials, travails and triumphs: an account of RNA catalysis in RNase P. J Mol Biol 2010; 397:627-46. [PMID: 20100492 DOI: 10.1016/j.jmb.2010.01.038] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2009] [Revised: 01/12/2010] [Accepted: 01/19/2010] [Indexed: 12/16/2022]
Abstract
Last December marked the 20th anniversary of the Nobel Prize in Chemistry to Sidney Altman and Thomas Cech for their discovery of RNA catalysts in bacterial ribonuclease P (an enzyme catalyzing 5' maturation of tRNAs) and a self-splicing rRNA of Tetrahymena, respectively. Coinciding with the publication of a treatise on RNase P, this review provides a historical narrative, a brief report on our current knowledge, and a discussion of some research prospects on RNase P.
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Affiliation(s)
- William H McClain
- Department of Bacteriology, College of Agriculture & Life Sciences, University of Wisconsin, Madison, WI 53706, USA.
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