1
|
Yu CH, Bhattacharya A, Persaud M, Taylor AB, Wang Z, Bulnes-Ramos A, Xu J, Selyutina A, Martinez-Lopez A, Cano K, Demeler B, Kim B, Hardies SC, Diaz-Griffero F, Ivanov DN. Nucleic acid binding by SAMHD1 contributes to the antiretroviral activity and is enhanced by the GpsN modification. Nat Commun 2021; 12:731. [PMID: 33531504 PMCID: PMC7854603 DOI: 10.1038/s41467-021-21023-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Accepted: 01/08/2021] [Indexed: 12/26/2022] Open
Abstract
SAMHD1 impedes infection of myeloid cells and resting T lymphocytes by retroviruses, and the enzymatic activity of the protein-dephosphorylation of deoxynucleotide triphosphates (dNTPs)-implicates enzymatic dNTP depletion in innate antiviral immunity. Here we show that the allosteric binding sites of the enzyme are plastic and can accommodate oligonucleotides in place of the allosteric activators, GTP and dNTP. SAMHD1 displays a preference for oligonucleotides containing phosphorothioate bonds in the Rp configuration located 3' to G nucleotides (GpsN), the modification pattern that occurs in a mechanism of antiviral defense in prokaryotes. In the presence of GTP and dNTPs, binding of GpsN-containing oligonucleotides promotes formation of a distinct tetramer with mixed occupancy of the allosteric sites. Mutations that impair formation of the mixed-occupancy complex abolish the antiretroviral activity of SAMHD1, but not its ability to deplete dNTPs. The findings link nucleic acid binding to the antiretroviral activity of SAMHD1, shed light on the immunomodulatory effects of synthetic phosphorothioated oligonucleotides and raise questions about the role of nucleic acid phosphorothioation in human innate immunity.
Collapse
Affiliation(s)
- Corey H Yu
- Department of Biochemistry and Structural Biology, UT Health San Antonio, San Antonio, TX, USA
| | - Akash Bhattacharya
- Department of Biochemistry and Structural Biology, UT Health San Antonio, San Antonio, TX, USA
| | - Mirjana Persaud
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Alexander B Taylor
- Department of Biochemistry and Structural Biology, UT Health San Antonio, San Antonio, TX, USA
| | - Zhonghua Wang
- Department of Biochemistry and Structural Biology, UT Health San Antonio, San Antonio, TX, USA
| | - Angel Bulnes-Ramos
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Joella Xu
- Department of Pediatrics, Emory School of Medicine, Atlanta, GA, USA
| | - Anastasia Selyutina
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Alicia Martinez-Lopez
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Kristin Cano
- Department of Biochemistry and Structural Biology, UT Health San Antonio, San Antonio, TX, USA
| | - Borries Demeler
- Department of Chemistry and Biochemistry, University of Lethbridge, Lethbridge, AB, Canada.,Department of Chemistry and Biochemistry, University of Montana, Missoula, MT, USA
| | - Baek Kim
- Department of Pediatrics, Emory School of Medicine, Atlanta, GA, USA
| | - Stephen C Hardies
- Department of Biochemistry and Structural Biology, UT Health San Antonio, San Antonio, TX, USA
| | - Felipe Diaz-Griffero
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY, USA.
| | - Dmitri N Ivanov
- Department of Biochemistry and Structural Biology, UT Health San Antonio, San Antonio, TX, USA.
| |
Collapse
|
2
|
Gholivand K, Azadbakht M, Maghsoud Y, Hosseini M, Kazak C. Synthesis, characterization, crystal structures, Hirshfeld surface analysis and theoretical calculations of some new bisphosphoramidate derivatives and novel binuclear triorganotin(IV) complexes with diphosphoryl ligand. J Organomet Chem 2019. [DOI: 10.1016/j.jorganchem.2018.10.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
3
|
Joshi P, Hussain N, Ali SR, Rishu R, Bhardwaj VK. Enhanced activity of trinuclear Zn(ii) complexes towards phosphate ester bond cleavage by introducing three-metal cooperativity. NEW J CHEM 2018. [DOI: 10.1039/c7nj03759g] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The catalytic efficiency (DNA binding followed by phosphate ester bond cleavage) of Zn(ii) complexes has been tuned by variation in the nuclearity, flexibility and coordination environment to explore the structure activity correlation.
Collapse
Affiliation(s)
- Pooja Joshi
- Department of Chemistry
- D.S.B. Campus
- Kumaun University
- Nainital
- India
| | - Navid Hussain
- Department of Chemistry
- Indian Institute of Technology Ropar
- Rupnagar
- India
| | - Shah Raj Ali
- Department of Chemistry
- D.S.B. Campus
- Kumaun University
- Nainital
- India
| | - Rishu Rishu
- Department of Chemistry
- MCM DAV College for Women
- Chandigarh-160036
- India
| | - Vimal K. Bhardwaj
- Department of Chemistry
- Indian Institute of Technology Ropar
- Rupnagar
- India
| |
Collapse
|
4
|
Shariatinia Z, Shekarriz S, Mirhosseini Mousavi HS, Maghsoudi N, Nikfar Z. Disperse dyeing and antibacterial properties of nylon and wool fibers using two novel nanosized copper(II) complexes bearing phosphoramide ligands. ARAB J CHEM 2017. [DOI: 10.1016/j.arabjc.2015.03.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
|
5
|
Anjana SS, Varghese B, Prasad E. Dinuclear cobalt(II) complexes with double phosphate ester bridges and tetradentate ligands having anisole or quinoline appendages. Acta Crystallogr C 2017; 73:492-497. [DOI: 10.1107/s2053229617007355] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Accepted: 05/17/2017] [Indexed: 11/11/2022] Open
Abstract
Phosphate esters provide a rigid and stable polymeric backbone in nucleic acids. Metal complexes with phosphate ester groups have been synthesized as structural and spectroscopic models of phosphate-containing enzymes. Dinucleating ligands are used extensively to synthesize model complexes since they provide the support required to stabilize such complexes. The crystal structures of two dinuclear CoII complexes, namely bis(μ-diphenyl phosphato-κ2
O:O′)bis({2-methoxy-N,N-bis[(pyridin-2-yl)methyl]aniline-κ4
N,N′,N′′,O}cobalt(II)) bis(perchlorate), [Co(C12H10O4P)2(C19H19N3O)2](ClO4)2, and bis(μ-diphenyl phosphato-κ2
O:O′)bis({N,N-bis[(pyridin-2-yl)methyl]quinolin-8-amine-κ4
N,N′,N′′,O}cobalt(II)) bis(perchlorate), [Co(C12H10O4P)2(C21H18N4)2](ClO4)2, with tetradentate 2-methoxy-N,N-bis[(pyridin-2-yl)methyl]aniline (L
1) and N,N-bis[(pyridin-2-yl)methyl]quinolin-8-amine (L
2) ligands are reported. The complexes have similar structures, with distorted octahedral geometries around the metal centres. Both are centrosymmetric (Z′ = 0.5), with the CoII centres doubly bridged by diphenyl phosphate ester groups. A number of aromatic–aromatic interactions are present and differ between the two complexes as the anisole group in L
1 is replaced by a quinoline group in L
2. A detailed study of these interactions is presented.
Collapse
|
6
|
Ding A, Xie R, Gu G, Sun J. Bromo-catalyzed photo esterification of benzylsilanes with alcohols under aerobic conditions. JOURNAL OF SAUDI CHEMICAL SOCIETY 2017. [DOI: 10.1016/j.jscs.2016.10.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
|
7
|
Wei H, Zhao G, Hu T, Tang S, Jiang J, Hu B, Guan Y. Mapping the nicking efficiencies of nickase R.BbvCI for side-specific LNA-substituted substrates using rolling circle amplification. Sci Rep 2016; 6:32560. [PMID: 27582033 PMCID: PMC5007493 DOI: 10.1038/srep32560] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Accepted: 08/09/2016] [Indexed: 11/29/2022] Open
Abstract
We used a novel asymmetric cleavage analysis method based on rolling circle amplification (RCA) to determine the effects of LNA modification of substrate on the two subunits of R.BbvCI cleavage. We designed two sets of cleavage circular substrates by using two different ligation strategies and analyzed the single strand cleavage efficiency affected by different modification positions both from the cleaved strands and the uncleaved strands. Results showed that the effects of LNA on cleavage rates of modified strands and unmodified strands were both site-dependent. The Nb.BbvCI and Nt.BbvCI were affected by LNA modification in different way. Most of the modification positions showed strong inhibition of both of these two nickases cleavage. However, the modification in T3 position of bottom strand hardly affected both of the two nickases activities. The results suggested an intimated interaction between the two subunits of R.BbvCI, and the T3 position in bottom strand might be a less tight position which was hard to be disturbed.
Collapse
Affiliation(s)
- Hua Wei
- Department of Biochemistry and Molecular Biology, China Medical University, #77 Puhe Road, Shenyang, Liaoning, 110122, China.,Animal Science and Veterinary Medicine College, Shenyang Agricultural University, Shenyang, Liaoning, 110866, China
| | - Guojie Zhao
- Department of Biochemistry and Molecular Biology, China Medical University, #77 Puhe Road, Shenyang, Liaoning, 110122, China
| | - Tianyu Hu
- Department of Biochemistry and Molecular Biology, China Medical University, #77 Puhe Road, Shenyang, Liaoning, 110122, China
| | - Suming Tang
- Department of Biochemistry and Molecular Biology, China Medical University, #77 Puhe Road, Shenyang, Liaoning, 110122, China
| | - Jiquan Jiang
- Department of Biochemistry and Molecular Biology, China Medical University, #77 Puhe Road, Shenyang, Liaoning, 110122, China
| | - Bo Hu
- Department of Biochemistry and Molecular Biology, China Medical University, #77 Puhe Road, Shenyang, Liaoning, 110122, China
| | - Yifu Guan
- Department of Biochemistry and Molecular Biology, China Medical University, #77 Puhe Road, Shenyang, Liaoning, 110122, China
| |
Collapse
|
8
|
Ziemniak M, Mugridge JS, Kowalska J, Rhoads RE, Gross JD, Jemielity J. Two-headed tetraphosphate cap analogs are inhibitors of the Dcp1/2 RNA decapping complex. RNA (NEW YORK, N.Y.) 2016; 22:518-29. [PMID: 26826132 PMCID: PMC4793208 DOI: 10.1261/rna.055152.115] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 12/10/2015] [Indexed: 05/08/2023]
Abstract
Dcp1/2 is the major eukaryotic RNA decapping complex, comprised of the enzyme Dcp2 and activator Dcp1, which removes the 5' m(7)G cap from mRNA, committing the transcript to degradation. Dcp1/2 activity is crucial for RNA quality control and turnover, and deregulation of these processes may lead to disease development. The molecular details of Dcp1/2 catalysis remain elusive, in part because both cap substrate (m(7)GpppN) and m(7)GDP product are bound by Dcp1/2 with weak (mM) affinity. In order to find inhibitors to use in elucidating the catalytic mechanism of Dcp2, we screened a small library of synthetic m(7)G nucleotides (cap analogs) bearing modifications in the oligophosphate chain. One of the most potent cap analogs, m(7)GpSpppSm(7)G, inhibited Dcp1/2 20 times more efficiently than m(7)GpppN or m(7)GDP. NMR experiments revealed that the compound interacts with specific surfaces of both regulatory and catalytic domains of Dcp2 with submillimolar affinities. Kinetics analysis revealed that m(7)GpSpppSm(7)G is a mixed inhibitor that competes for the Dcp2 active site with micromolar affinity. m(7)GpSpppSm(7)G-capped RNA undergoes rapid decapping, suggesting that the compound may act as a tightly bound cap mimic. Our identification of the first small molecule inhibitor of Dcp2 should be instrumental in future studies aimed at understanding the structural basis of RNA decapping and may provide insight toward the development of novel therapeutically relevant decapping inhibitors.
Collapse
Affiliation(s)
- Marcin Ziemniak
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, 02-089 Warsaw, Poland
| | - Jeffrey S Mugridge
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California 94158, USA
| | - Joanna Kowalska
- Division of Biophysics, Institute of Experimental Physics, Faculty of Physics, University of Warsaw, 02-089 Warsaw, Poland
| | - Robert E Rhoads
- Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, Shreveport, Louisiana 71130-3932, USA
| | - John D Gross
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California 94158, USA
| | - Jacek Jemielity
- Centre of New Technologies, University of Warsaw, 02-097 Warsaw, Poland
| |
Collapse
|
9
|
Zhang X, Liu X, Phillips DL, Zhao C. Mechanistic Insights Into the Factors That Influence the DNA Nuclease Activity of Mononuclear Facial Copper Complexes Containing Hetero-Substituted Cyclens. ACS Catal 2015. [DOI: 10.1021/acscatal.5b01735] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Xuepeng Zhang
- MOE
Key Laboratory of Bioinorganic and Synthetic Chemistry, School of
Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, P. R. China
| | - Xueping Liu
- MOE
Key Laboratory of Bioinorganic and Synthetic Chemistry, School of
Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, P. R. China
| | - David Lee Phillips
- Department
of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P. R. China
| | - Cunyuan Zhao
- MOE
Key Laboratory of Bioinorganic and Synthetic Chemistry, School of
Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, P. R. China
| |
Collapse
|
10
|
Dunican BF, Hiller DA, Strobel SA. Transition State Charge Stabilization and Acid-Base Catalysis of mRNA Cleavage by the Endoribonuclease RelE. Biochemistry 2015; 54:7048-57. [PMID: 26535789 DOI: 10.1021/acs.biochem.5b00866] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The bacterial toxin RelE is a ribosome-dependent endoribonuclease. It is part of a type II toxin-antitoxin system that contributes to antibiotic resistance and biofilm formation. During amino acid starvation, RelE cleaves mRNA in the ribosomal A-site, globally inhibiting protein translation. RelE is structurally similar to microbial RNases that employ general acid-base catalysis to facilitate RNA cleavage. The RelE active site is atypical for acid-base catalysis, in that it is enriched with positively charged residues and lacks the prototypical histidine-glutamate catalytic pair, making the mechanism of mRNA cleavage unclear. In this study, we use a single-turnover kinetic analysis to measure the effect of pH and phosphorothioate substitution on the rate constant for cleavage of mRNA by wild-type RelE and seven active-site mutants. Mutation and thio effects indicate a major role for stabilization of increased negative change in the transition state by arginine 61. The wild-type RelE cleavage rate constant is pH-independent, but the reaction catalyzed by many of the mutants is strongly dependent on pH, suggestive of general acid-base catalysis. pH-rate curves indicate that wild-type RelE operates with the pK(a) of at least one catalytic residue significantly downshifted by the local environment. Mutation of any single active-site residue is sufficient to disrupt this microenvironment and revert the shifted pK(a) back above neutrality. pH-rate curves are consistent with K54 functioning as a general base and R81 as a general acid. The capacity of RelE to effect a large pK(a) shift and facilitate a common catalytic mechanism by uncommon means furthers our understanding of other atypical enzymatic active sites.
Collapse
Affiliation(s)
- Brian F Dunican
- Department of Molecular Biophysics and Biochemistry, Yale University , New Haven, Connecticut 06511, United States
| | - David A Hiller
- Department of Molecular Biophysics and Biochemistry, Yale University , New Haven, Connecticut 06511, United States
| | - Scott A Strobel
- Department of Molecular Biophysics and Biochemistry, Yale University , New Haven, Connecticut 06511, United States
| |
Collapse
|
11
|
Olorunniji FJ, McPherson AL, Pavlou HJ, McIlwraith MJ, Brazier JA, Cosstick R, Stark WM. Nicked-site substrates for a serine recombinase reveal enzyme-DNA communications and an essential tethering role of covalent enzyme-DNA linkages. Nucleic Acids Res 2015; 43:6134-43. [PMID: 25990737 PMCID: PMC4499144 DOI: 10.1093/nar/gkv521] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Revised: 04/30/2015] [Accepted: 05/07/2015] [Indexed: 11/12/2022] Open
Abstract
To analyse the mechanism and kinetics of DNA strand cleavages catalysed by the serine recombinase Tn3 resolvase, we made modified recombination sites with a single-strand nick in one of the two DNA strands. Resolvase acting on these sites cleaves the intact strand very rapidly, giving an abnormal half-site product which accumulates. We propose that these reactions mimic second-strand cleavage of an unmodified site. Cleavage occurs in a synapse of two sites, held together by a resolvase tetramer; cleavage at one site stimulates cleavage at the partner site. After cleavage of a nicked-site substrate, the half-site that is not covalently linked to a resolvase subunit dissociates rapidly from the synapse, destabilizing the entire complex. The covalent resolvase-DNA linkages in the natural reaction intermediate thus perform an essential DNA-tethering function. Chemical modifications of a nicked-site substrate at the positions of the scissile phosphodiesters result in abolition or inhibition of resolvase-mediated cleavage and effects on resolvase binding and synapsis, providing insight into the serine recombinase catalytic mechanism and how resolvase interacts with the substrate DNA.
Collapse
Affiliation(s)
- Femi J Olorunniji
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, Bower Building, Glasgow G12 8QQ, UK
| | - Arlene L McPherson
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, Bower Building, Glasgow G12 8QQ, UK
| | - Hania J Pavlou
- Department of Physiology, Anatomy and Genetics, University of Oxford, Sherrington Building, Parks Road, Oxford OX1 3PT, UK
| | - Michael J McIlwraith
- Beatson Institute for Cancer Research, Switchback Road, Bearsden, Glasgow G61 1BD, UK
| | - John A Brazier
- Reading School of Pharmacy, University of Reading, Whiteknights, Reading, Berkshire, RG6 6AD, UK
| | - Richard Cosstick
- Department of Chemistry, University of Liverpool, Crown Street, Liverpool, L69 7ZD, UK
| | - W Marshall Stark
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, Bower Building, Glasgow G12 8QQ, UK
| |
Collapse
|
12
|
Seamon KJ, Sun Z, Shlyakhtenko LS, Lyubchenko YL, Stivers JT. SAMHD1 is a single-stranded nucleic acid binding protein with no active site-associated nuclease activity. Nucleic Acids Res 2015; 43:6486-99. [PMID: 26101257 PMCID: PMC4513882 DOI: 10.1093/nar/gkv633] [Citation(s) in RCA: 101] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Accepted: 06/05/2015] [Indexed: 12/15/2022] Open
Abstract
The HIV-1 restriction factor SAMHD1 is a tetrameric enzyme activated by guanine nucleotides with dNTP triphosphate hydrolase activity (dNTPase). In addition to this established activity, there have been a series of conflicting reports as to whether the enzyme also possesses single-stranded DNA and/or RNA 3′-5′ exonuclease activity. SAMHD1 was purified using three chromatography steps, over which the DNase activity was largely separated from the dNTPase activity, but the RNase activity persisted. Surprisingly, we found that catalytic and nucleotide activator site mutants of SAMHD1 with no dNTPase activity retained the exonuclease activities. Thus, the exonuclease activity cannot be associated with any known dNTP binding site. Monomeric SAMHD1 was found to bind preferentially to single-stranded RNA, while the tetrameric form required for dNTPase action bound weakly. ssRNA binding, but not ssDNA, induces higher-order oligomeric states that are distinct from the tetrameric form that binds dNTPs. We conclude that the trace exonuclease activities detected in SAMHD1 preparations arise from persistent contaminants that co-purify with SAMHD1 and not from the HD active site. An in vivo model is suggested where SAMHD1 alternates between the mutually exclusive functions of ssRNA binding and dNTP hydrolysis depending on dNTP pool levels and the presence of viral ssRNA.
Collapse
Affiliation(s)
- Kyle J Seamon
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205-2185, USA
| | - Zhiqiang Sun
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, NE 68198-6025, USA
| | - Luda S Shlyakhtenko
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, NE 68198-6025, USA
| | - Yuri L Lyubchenko
- Department of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, 986025 Nebraska Medical Center, Omaha, NE 68198-6025, USA
| | - James T Stivers
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, MD 21205-2185, USA
| |
Collapse
|
13
|
Zhao G, Hu T, Li J, Wei H, Shang H, Guan Y. A RCA-based assay for analyzing individual strand break in DNA heteroduplex cleavage by restriction endonucleases. Chem Commun (Camb) 2015; 50:11930-3. [PMID: 25157639 DOI: 10.1039/c4cc05314a] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We have developed a rapid and high-throughput assay based on rolling circle amplification, to distinguish individual strand cleavage of DNA duplexes by restriction endonucleases. As an illustration, we analyzed nicking activity of Nb.BbvCI and uneven cleavage of LNA modified DNA by EcoRI. This assay has potential for analyzing protein-DNA interactions.
Collapse
Affiliation(s)
- Guojie Zhao
- Key Laboratory of Medical Cell Biology (Ministry of Education), Department of Biochemistry and Molecular Biology, China Medical University, Shenyang, Liaoning 110001, China.
| | | | | | | | | | | |
Collapse
|
14
|
Zhang X, Zhu Y, Gao H, Zhao C. Solvolysis Mechanisms of RNA Phosphodiester Analogues Promoted by Mononuclear Zinc(II) Complexes: Mechanisic Determination upon Solvent Medium and Ligand Effects. Inorg Chem 2014; 53:11903-12. [DOI: 10.1021/ic501084a] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Xuepeng Zhang
- MOE
Key Laboratory of Bioinorganic and Synthetic Chemistry, School of
Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, P. R. China
| | - Yajie Zhu
- MOE
Key Laboratory of Bioinorganic and Synthetic Chemistry, School of
Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, P. R. China
| | - Hui Gao
- Key
Laboratory of Renewable Energy and Gas Hydrate, Guangzhou Institute
of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, P. R. China
| | - Cunyuan Zhao
- MOE
Key Laboratory of Bioinorganic and Synthetic Chemistry, School of
Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, P. R. China
| |
Collapse
|
15
|
Shariatinia Z, Dusek M, Eigner V. Synthesis, X-ray Crystallography, and DFT Calculations of A Novel Phosphoramide. Z Anorg Allg Chem 2014. [DOI: 10.1002/zaac.201400285] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
16
|
Chang H, Yanachkov IB, Dix EJ, Yanachkova M, Li Y, Barnard MR, Wright GE, Michelson AD, Frelinger AL. Antiplatelet activity, P2Y₁ and P2Y₁₂ inhibition, and metabolism in plasma of stereoisomers of diadenosine 5',5'″-P¹ ,P⁴-dithio-P²,P³-chloromethylenetetraphosphate. PLoS One 2014; 9:e94780. [PMID: 24722456 PMCID: PMC3983250 DOI: 10.1371/journal.pone.0094780] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Accepted: 03/19/2014] [Indexed: 12/18/2022] Open
Abstract
Background Diadenosine tetraphosphate (Ap4A), a constituent of platelet dense granules, and its P1,P4-dithio and/or P2,P3-chloromethylene analogs, inhibit adenosine diphosphate (ADP)-induced platelet aggregation. We recently reported that these compounds antagonize both platelet ADP receptors, P2Y1 and P2Y12. The most active of those analogs, diadenosine 5′,5″″-P1,P4-dithio-P2,P3-chloromethylenetetraphosphate, (compound 1), exists as a mixture of 4 stereoisomers. Objective To separate the stereoisomers of compound 1 and determine their effects on platelet aggregation, platelet P2Y1 and P2Y12 receptor antagonism, and their metabolism in human plasma. Methods We separated the 4 diastereomers of compound 1 by preparative reversed-phase chromatography, and studied their effect on ADP-induced platelet aggregation, P2Y1-mediated changes in cytosolic Ca2+, P2Y12-mediated changes in VASP phosphorylation, and metabolism in human plasma. Results The inhibition of ADP-induced human platelet aggregation and human platelet P2Y12 receptor, and stability in human plasma strongly depended on the stereo-configuration of the chiral P1- and P4-phosphorothioate groups, the SPSP diastereomer being the most potent inhibitor and completely resistant to degradation in plasma, and the RPRP diastereomer being the least potent inhibitor and with the lowest plasma stability. The inhibitory activity of SPRP diastereomers depended on the configuration of the pseudo-asymmetric carbon of the P2,P3-chloromethylene group, one of the configurations being significantly more active than the other. Their plasma stability did not differ significantly, being intermediate to that of the SPSP and the RPRP diastereomers. Conclusions The presently-described stereoisomers have utility for structural, mechanistic, and drug development studies of dual antagonists of platelet P2Y1 and P2Y12 receptors.
Collapse
Affiliation(s)
- Hung Chang
- Center for Platelet Function Studies, Department of Pediatrics, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Hematology Division, Chang Gung Memorial Hospital, Chang Gung University, Taipei, Taiwan
| | - Ivan B. Yanachkov
- GLSynthesis Inc., Worcester, Massachusetts, United States of America
| | - Edward J. Dix
- GLSynthesis Inc., Worcester, Massachusetts, United States of America
| | - Milka Yanachkova
- GLSynthesis Inc., Worcester, Massachusetts, United States of America
| | - YouFu Li
- Center for Platelet Function Studies, Department of Pediatrics, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Marc R. Barnard
- Center for Platelet Function Studies, Department of Pediatrics, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - George E. Wright
- GLSynthesis Inc., Worcester, Massachusetts, United States of America
| | - Alan D. Michelson
- Center for Platelet Function Studies, Department of Pediatrics, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Center for Platelet Research Studies, Division of Hematology/Oncology, Boston Children's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Andrew L. Frelinger
- Center for Platelet Function Studies, Department of Pediatrics, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- Center for Platelet Research Studies, Division of Hematology/Oncology, Boston Children's Hospital, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
| |
Collapse
|
17
|
Zhang X, Xu X, Xu H, Zhang X, Phillips DL, Zhao C. Mechanistic Investigation into the Cleavage of a Phosphomonoester Mediated by a Symmetrical Oxyimine-Based Macrocyclic Zinc(II) Complex. Chemphyschem 2014; 15:1887-98. [DOI: 10.1002/cphc.201301216] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Revised: 01/24/2014] [Indexed: 11/08/2022]
|
18
|
Griffin MA, Davis JH, Strobel SA. Bacterial toxin RelE: a highly efficient ribonuclease with exquisite substrate specificity using atypical catalytic residues. Biochemistry 2013; 52:8633-42. [PMID: 24251350 DOI: 10.1021/bi401325c] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The toxin RelE is a ribosome-dependent endoribonuclease implicated in diverse cellular processes, including persistence. During amino acid starvation, RelE inhibits translation by cleaving ribosomal A-site mRNA. Although RelE is structurally similar to other microbial endoribonucleases, the active-site amino acid composition differs substantially and lacks obvious candidates for general acid-base functionality. Highly conserved RelE residues (Lys52, Lys54, Arg61, Arg81, and Tyr87) surround the mRNA scissile phosphate, and specific 16S rRNA contacts further contribute to substrate positioning. We used a single-turnover kinetic assay to evaluate the catalytic importance of individual residues in the RelE active site. Within the context of the ribosome, RelE rapidly cleaves A-site mRNA at a rate similar to those of traditional ribonucleases. Single-turnover rate constants decreased between 10(2)- and 10(6)-fold for the RelE active-site mutants of Lys52, Lys54, Arg61, and Arg81. RelE may principally promote catalysis via transition-state charge stabilization and leaving-group protonation, in addition to achieving in-line substrate positioning in cooperation with the ribosome. This kinetic analysis complements structural information to provide a foundation for understanding the molecular mechanism of this atypical endoribonuclease.
Collapse
Affiliation(s)
- Meghan A Griffin
- Department of Molecular Biophysics and Biochemistry, Yale University , New Haven, Connecticut 06511, United States
| | | | | |
Collapse
|
19
|
Improved Performance of Anti-miRNA Oligonucleotides Using a Novel Non-Nucleotide Modifier. MOLECULAR THERAPY-NUCLEIC ACIDS 2013; 2:e117. [PMID: 23982190 PMCID: PMC3759741 DOI: 10.1038/mtna.2013.46] [Citation(s) in RCA: 112] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 06/24/2013] [Indexed: 01/01/2023]
Abstract
Anti-microRNA oligonucleotides (AMOs) are steric blocking antisense reagents that inhibit microRNA (miRNA) function by hybridizing and repressing the activity of a mature miRNA. First generation AMOs employed 2'-O-Methyl RNA nucleotides (2'OMe) with phosphorothioate (PS) internucleotide linkages positioned at both ends to block exonuclease attack. Second generation AMOs improved potency through the use of chemical modifications that increase binding affinity to the target, such as locked nucleic acid (LNA) residues. However, this strategy can reduce specificity as high binding affinity compounds can bind to and suppress function of related sequences even if one or more mismatches are present. Further, unnatural modified nucleic acid residues can have toxic side effects. In the present study, a variety of non-nucleotide modifiers were screened for utility in steric blocking antisense applications. A novel compound, N,N-diethyl-4-(4-nitronaphthalen-1-ylazo)-phenylamine ("ZEN"), was discovered that increased binding affinity and blocked exonuclease degradation when placed at or near each end of a single-stranded oligonucleotide. This new modification was combined with the 2'OMe RNA backbone to make ZEN-AMOs. The new ZEN-AMOs have high potency and can effectively inhibit miRNA function in vitro at low nanomolar concentrations, show high specificity, and have low toxicity in cell culture.Molecular Therapy-Nucleic Acids (2013) 2, e117; doi:10.1038/mtna.2013.46; published online 27 August 2013.
Collapse
|
20
|
Shariatinia Z, Sohrabi M, Yousefi M, Koval T, Dusek M. Phosphoramidates: Synthesis, spectroscopy, and X-Ray crystallography. HETEROATOM CHEMISTRY 2012. [DOI: 10.1002/hc.21040] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
21
|
Guga P, Koziołkiewicz M. Phosphorothioate nucleotides and oligonucleotides - recent progress in synthesis and application. Chem Biodivers 2012; 8:1642-81. [PMID: 21922655 DOI: 10.1002/cbdv.201100130] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Affiliation(s)
- Piotr Guga
- Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Department of Bioorganic Chemistry, Sienkiewicza 112, PL-90-363 Łódź.
| | | |
Collapse
|
22
|
Carrasco N, Hiller DA, Strobel SA. Minimal Transition State Charge Stabilization of the Oxyanion during Peptide Bond Formation by the Ribosome. Biochemistry 2011; 50:10491-8. [DOI: 10.1021/bi201290s] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Nicolas Carrasco
- Departments of Molecular Biophysics & Biochemistry and Chemistry, Yale University, 260 Whitney Ave., New Haven, Connecticut 06520-81114, United States
| | - David A. Hiller
- Departments of Molecular Biophysics & Biochemistry and Chemistry, Yale University, 260 Whitney Ave., New Haven, Connecticut 06520-81114, United States
| | - Scott A. Strobel
- Departments of Molecular Biophysics & Biochemistry and Chemistry, Yale University, 260 Whitney Ave., New Haven, Connecticut 06520-81114, United States
| |
Collapse
|
23
|
Lassila JK, Zalatan JG, Herschlag D. Biological phosphoryl-transfer reactions: understanding mechanism and catalysis. Annu Rev Biochem 2011; 80:669-702. [PMID: 21513457 DOI: 10.1146/annurev-biochem-060409-092741] [Citation(s) in RCA: 286] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Phosphoryl-transfer reactions are central to biology. These reactions also have some of the slowest nonenzymatic rates and thus require enormous rate accelerations from biological catalysts. Despite the central importance of phosphoryl transfer and the fascinating catalytic challenges it presents, substantial confusion persists about the properties of these reactions. This confusion exists despite decades of research on the chemical mechanisms underlying these reactions. Here we review phosphoryl-transfer reactions with the goal of providing the reader with the conceptual and experimental background to understand this body of work, to evaluate new results and proposals, and to apply this understanding to enzymes. We describe likely resolutions to some controversies, while emphasizing the limits of our current approaches and understanding. We apply this understanding to enzyme-catalyzed phosphoryl transfer and provide illustrative examples of how this mechanistic background can guide and deepen our understanding of enzymes and their mechanisms of action. Finally, we present important future challenges for this field.
Collapse
Affiliation(s)
- Jonathan K Lassila
- Department of Biochemistry, Stanford University, Stanford, California 94305, USA.
| | | | | |
Collapse
|
24
|
Gao H, Ke Z, DeYonker NJ, Wang J, Xu H, Mao ZW, Phillips DL, Zhao C. Dinuclear Zn(II) Complex Catalyzed Phosphodiester Cleavage Proceeds via a Concerted Mechanism: A Density Functional Theory Study. J Am Chem Soc 2011; 133:2904-15. [DOI: 10.1021/ja106456u] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Affiliation(s)
- Hui Gao
- MOE Key Laboratory of Bioinorganic and Synthetic Chemistry/KLGHEI of Environment and Energy Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, P. R. China
| | - Zhuofeng Ke
- MOE Key Laboratory of Bioinorganic and Synthetic Chemistry/KLGHEI of Environment and Energy Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, P. R. China
| | - Nathan J. DeYonker
- Department of Chemistry, The University of Memphis, Memphis, Tennessee 38152-3550, United States
| | - Juping Wang
- MOE Key Laboratory of Bioinorganic and Synthetic Chemistry/KLGHEI of Environment and Energy Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, P. R. China
| | - Huiying Xu
- MOE Key Laboratory of Bioinorganic and Synthetic Chemistry/KLGHEI of Environment and Energy Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, P. R. China
| | - Zong-Wan Mao
- MOE Key Laboratory of Bioinorganic and Synthetic Chemistry/KLGHEI of Environment and Energy Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, P. R. China
| | - David Lee Phillips
- Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, P. R. China
| | - Cunyuan Zhao
- MOE Key Laboratory of Bioinorganic and Synthetic Chemistry/KLGHEI of Environment and Energy Chemistry, School of Chemistry and Chemical Engineering, Sun Yat-Sen University, Guangzhou 510275, P. R. China
| |
Collapse
|
25
|
López-Banet L, Santana MD, García G, García L, Pérez J, Rojo T, Lezama L, Costes JP. Crystal Structures and Magnetic Properties of Nickel Complexes with Hydrotris(pyrazolyl)borate Ligand and Double Bridged by Phosphate Esters. Inorg Chem 2010; 50:437-43. [DOI: 10.1021/ic100980x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Luisa López-Banet
- Departamento de Química Inorgánica, Universidad de Murcia, E-30071 Murcia, Spain
| | - M. Dolores Santana
- Departamento de Química Inorgánica, Universidad de Murcia, E-30071 Murcia, Spain
| | - Gabriel García
- Departamento de Química Inorgánica, Universidad de Murcia, E-30071 Murcia, Spain
| | - Luis García
- Departamento de Ingeniería Minera, Geológica y Cartográfica, Área de Química Inorgánica, Universidad Politécnica de Cartagena, E-30203 Cartagena, Spain
| | - José Pérez
- Departamento de Ingeniería Minera, Geológica y Cartográfica, Área de Química Inorgánica, Universidad Politécnica de Cartagena, E-30203 Cartagena, Spain
| | - Teófilo Rojo
- Departamento de Química Inorgánica, Facultad de Ciencia y Tecnología, Universidad del País Vasco, E-48080 Bilbao, Spain
| | - Luis Lezama
- Departamento de Química Inorgánica, Facultad de Ciencia y Tecnología, Universidad del País Vasco, E-48080 Bilbao, Spain
| | - Jean-Pierre Costes
- Laboratoire de Chimie de Coordination du CNRS, UPR 8241, liée par conventions à l’Université Paul Sabatier et à l’Institut National Polytechnique de Toulouse, 205 route de Narbonne, 31077 Toulouse Cedex, France
| |
Collapse
|
26
|
Bai C, Zhao L, Tsai MD, Bruzik KS. Unique catalytic mechanism of phosphatidylinositol-specific phospholipase C from Streptomyces antibioticus. J Am Chem Soc 2010; 132:1210-1. [PMID: 20052980 DOI: 10.1021/ja908285h] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Calcium-dependent phosphatidylinositol-specific phospholipase C from Streptomyces antibioticus (saPLC1) catalyzes hydrolysis of phosphatidylinositol (PI) into inositol 1-phosphate by a unique mechanism involving formation of inositol 1,6-cyclic phosphate (1,6-IcP) as an intermediate. This work examines the rates and products of cleavage of phosphorothioate and phosphorodithioate analogues of PI in which sulfur was introduced into the phosphate moiety at a nonbridging position (pro-R or pro-S), a bridging position, or both. The replacement of the pro-S oxygen in the phosphoryl moiety of PI by sulfur results in a 3 x 10(7)-fold decrease of the catalytic rate constant, whereas alteration of the pro-R oxygen results in only a modest rate reduction. The addition of the second sulfur atom into the bridging position of the S(p) isomer of the phosphorothioate analogue causes a dramatic (2 x 10(5)-fold) increase of the rate of cleavage but has a negligible effect on the R(p) isomer. These differences are consistent with a change in the mechanism for the S(p) isomer of the phosphorodithioate analogue into a more dissociative type, where the leaving group carries a large amount of negative charge. In addition, hydrolysis of the diastereomers of the phosphorothioate analogues of 1,6-IcP, inositol cis-1,6-IcPs and inositol trans-1,6-IcPs, affords two distinct products, inositol 1-phosphorothioate and inositol 6-phosphorothioate, respectively. Formation of inositol 6-phosphorothioate is explained by the binding of trans-1,6-IcPs in the active site in a rotated orientation that interchanges the oxygen atoms at the 1- and 6-positions, thereby allowing the hydroxyl group at the 1-position to act as a leaving group. The reorientation of the intermediate is driven by formation of favorable interactions of the enzyme active site with the nonbridging oxygen in the trans intermediate.
Collapse
Affiliation(s)
- Chuan Bai
- Department of Medicinal Chemistry and Pharmacognosy, The University of Illinois at Chicago, Chicago, Illinois 60612, USA
| | | | | | | |
Collapse
|
27
|
Wu X, Goswami K, Shimizu KD. Comparison of monofunctional and multifunctional monomers in phosphate binding molecularly imprinted polymers. J Mol Recognit 2008; 21:410-8. [DOI: 10.1002/jmr.912] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
28
|
Wang M, Boddy CN. Examining the Role of Hydrogen Bonding Interactions in the Substrate Specificity for the Loading Step of Polyketide Synthase Thioesterase Domains. Biochemistry 2008; 47:11793-803. [DOI: 10.1021/bi800963y] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Meng Wang
- Department of Chemistry, Syracuse University, Syracuse, New York 13244-4100
| | | |
Collapse
|
29
|
Parker JB, Stivers JT. Uracil DNA glycosylase: revisiting substrate-assisted catalysis by DNA phosphate anions. Biochemistry 2008; 47:8614-22. [PMID: 18652484 DOI: 10.1021/bi800854g] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Uracil DNA glycosylase (UNG) is a powerful DNA repair enzyme that has been shown to stabilize a glycosyl cation reaction intermediate and a related tight binding inhibitor using electrostatic interactions with the +1 and -1, but not the +2, phosphodiester group of the single-stranded DNA substrate Ap (2+)Ap (1+)Up (1-)ApA. These experimental results differed considerably from computational findings using duplex DNA, where the +2 phosphate was found to stabilize the transition state by approximately 5 kcal/mol, suggesting that UNG uses different catalytic strategies with single-stranded and double-stranded DNA substrates. In addition, the computational studies indicated that the conserved and positively charged His148 (which hydrogen bonds to the +2 phosphate) destabilized the glycosyl cation intermediate by 6-8 kcal/mol through anticatalytic electrostatic interactions. To evaluate these interesting proposals, we measured the kinetic effects of neutral methylphosphonate (MeP) stereoisomers at the +1 and +2 positions of a 12-mer dsDNA substrate and also the catalytic contribution and ionization state of His148. For MeP substitutions at the +1 position, single-turnover kinetic studies showed that the activation barrier was increased by 9.8 and 3.1 kcal/mol, corresponding to a stereoselectivity of nearly 40000-fold for the respective MeP isomers. Identical to the findings with ssDNA, MeP substitutions at the +2 position resulted in only small changes in the activation barrier (+/-0.3 kcal/mol), with little stereoselectivity ( approximately 4-fold). However, the H148A mutation destabilizes both the ground state and transition states by 2.4 and 4.3 kcal/mol, respectively. Thus, His148 is catalytic because it stabilizes the transition state to a greater extent (1.9 kcal/mol) than the ground state. Heteronuclear NMR studies established that His148 was neutral in the free enzyme at neutral pH, and in conformational exchange in a specific DNA complex containing uracil. We conclude that the +1 and +2 phosphate esters play identical catalytic roles in the reactions of single-stranded and double-stranded DNA substrates, and that His148 serves a catalytic role by positioning the substrate and catalytic water, or by an environmental effect.
Collapse
Affiliation(s)
- Jared B Parker
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, 725 North Wolfe Street, Baltimore, Maryland 21205-2185, USA
| | | |
Collapse
|
30
|
Iyer S, Hengge AC. The effects of sulfur substitution for the nucleophile and bridging oxygen atoms in reactions of hydroxyalkyl phosphate esters. J Org Chem 2008; 73:4819-29. [PMID: 18533704 PMCID: PMC2575009 DOI: 10.1021/jo8002198] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The effects of sulfur substitution on the reactions of hydroxyalkyl phosphate esters are examined. These compounds are models for the intramolecular phosphoryl transfer reaction involved in the cleavage of the internucleotide bond in RNA. The models studied here lack the ribose ring and their conformational flexibility results in greater stability and the availability of different reaction pathways. Sulfur in the nucleophilic position shows no nucleophilic reaction at phosphorus, instead rapidly attacking at the beta carbon atom, forming thiirane with departure of a phosphomonoester. Sulfur substitution at either of the two bridging positions leads to cleavage of the diester via formation of a cyclic intermediate, but with significant rate acceleration when compared to the oxygen analogues. The bridge-substituted models react substantially slower than the analogous ribose compounds with sulfur substitution at comparable positions. Kinetic isotope effects reveal significant differences in the transition state depending on which bridging position sulfur occupies. When sulfur is in the scissile bridging position, a highly associative transition state is indicated, with a largely formed bond to the nucleophile and the scissile P-S bond is little changed. When sulfur occupies the other bridging position, the isotope effects imply a very early transition state in a concerted reaction.
Collapse
Affiliation(s)
- Subashree Iyer
- Utah State University, Department of Chemistry and Biochemistry, Logan, Utah 84322-0300, USA
| | | |
Collapse
|