1
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Salihovic A, Ascham A, Taladriz-Sender A, Bryson S, Withers JM, McKean IJW, Hoskisson PA, Grogan G, Burley GA. Gram-scale enzymatic synthesis of 2'-deoxyribonucleoside analogues using nucleoside transglycosylase-2. Chem Sci 2024:d4sc04938a. [PMID: 39234214 PMCID: PMC11368039 DOI: 10.1039/d4sc04938a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2024] [Accepted: 08/26/2024] [Indexed: 09/06/2024] Open
Abstract
Nucleosides are pervasive building blocks that are found throughout nature and used extensively in medicinal chemistry and biotechnology. However, the preparation of base-modified analogues using conventional synthetic methodology poses challenges in scale-up and purification. In this work, an integrated approach involving structural analysis, screening and reaction optimization, is established to prepare 2'-deoxyribonucleoside analogues catalysed by the type II nucleoside 2'-deoxyribosyltransferase from Lactobacillus leichmannii (LlNDT-2). Structural analysis in combination with substrate profiling, identified the constraints on pyrimidine and purine acceptor bases by LlNDT2. A solvent screen identifies pure water as a suitable solvent for the preparation of high value purine and pyrimidine 2'-deoxyribonucleoside analogues on a gram scale under optimized reaction conditions. This approach provides the basis to establish a convergent, step-efficient chemoenzymatic platform for the preparation of high value 2'-deoxyribonucleosides.
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Affiliation(s)
- Admir Salihovic
- Department of Pure & Applied Chemistry, University of Strathclyde 295 Cathedral Street Glasgow UK G1 1XL
- Strathclyde Centre for Molecular Bioscience, University of Strathclyde UK
| | - Alex Ascham
- Department of Chemistry, University of York, Heslington York YO10 5DD UK
| | - Andrea Taladriz-Sender
- Department of Pure & Applied Chemistry, University of Strathclyde 295 Cathedral Street Glasgow UK G1 1XL
- Strathclyde Centre for Molecular Bioscience, University of Strathclyde UK
| | - Samantha Bryson
- Department of Pure & Applied Chemistry, University of Strathclyde 295 Cathedral Street Glasgow UK G1 1XL
- Strathclyde Centre for Molecular Bioscience, University of Strathclyde UK
| | - Jamie M Withers
- Department of Pure & Applied Chemistry, University of Strathclyde 295 Cathedral Street Glasgow UK G1 1XL
- Strathclyde Centre for Molecular Bioscience, University of Strathclyde UK
| | - Iain J W McKean
- Department of Pure & Applied Chemistry, University of Strathclyde 295 Cathedral Street Glasgow UK G1 1XL
- Strathclyde Centre for Molecular Bioscience, University of Strathclyde UK
| | - Paul A Hoskisson
- Strathclyde Institute of Pharmacy & Biomedical Sciences, University of Strathclyde 161 Cathedral Street Glasgow G4 0RE UK
| | - Gideon Grogan
- Department of Chemistry, University of York, Heslington York YO10 5DD UK
| | - Glenn A Burley
- Department of Pure & Applied Chemistry, University of Strathclyde 295 Cathedral Street Glasgow UK G1 1XL
- Strathclyde Centre for Molecular Bioscience, University of Strathclyde UK
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2
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Liu G, Wang J, Chu J, Jiang T, Qin S, Gao Z, He B. Engineering Substrate Promiscuity of Nucleoside Phosphorylase Via an Insertions-Deletions Strategy. JACS AU 2024; 4:454-464. [PMID: 38425912 PMCID: PMC10900210 DOI: 10.1021/jacsau.3c00581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 12/27/2023] [Accepted: 01/02/2024] [Indexed: 03/02/2024]
Abstract
Nucleoside phosphorylases (NPs) are the key enzymes in the nucleoside metabolism pathway and are widely employed for the synthesis of nucleoside analogs, which are difficult to access via conventional synthetic methods. NPs are generally classified as purine nucleoside phosphorylase (PNP) and pyrimidine or uridine nucleoside phosphorylase (PyNP/UP), based on their substrate preference. Here, based on the evolutionary information on the NP-I family, we adopted an insertions-deletions (InDels) strategy to engineer the substrate promiscuity of nucleoside phosphorylase AmPNPΔS2V102 K, which exhibits both PNP and UP activities from a trimeric PNP (AmPNP) of Aneurinibacillus migulanus. Furthermore, the AmPNPΔS2V102 K exerted phosphorylation activities toward arabinose nucleoside, fluorosyl nucleoside, and dideoxyribose, thereby broadening the unnatural-ribose nucleoside substrate spectrum of AmPNP. Finally, six purine nucleoside analogues were successfully synthesized, using the engineered AmPNPΔS2V102 K instead of the traditional "two-enzymes PNP/UP" approach. These results provide deep insights into the catalytic mechanisms of the PNP and demonstrate the benefits of using the InDels strategy to achieve substrate promiscuity in an enzyme, as well as broadening the substrate spectrum of the enzyme.
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Affiliation(s)
- Gaofei Liu
- College
of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, China
| | - Jialing Wang
- College
of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, China
| | - Jianlin Chu
- School
of Pharmaceutical Sciences, Nanjing Tech
University, Nanjing 211800, China
| | - Tianyue Jiang
- School
of Pharmaceutical Sciences, Nanjing Tech
University, Nanjing 211800, China
| | - Song Qin
- School
of Pharmaceutical Sciences, Nanjing Tech
University, Nanjing 211800, China
| | - Zhen Gao
- College
of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, China
| | - Bingfang He
- College
of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, Nanjing 211800, China
- School
of Pharmaceutical Sciences, Nanjing Tech
University, Nanjing 211800, China
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3
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Chung Z, Lin J, Wirjanata G, Dziekan JM, El Sahili A, Preiser PR, Bozdech Z, Lescar J. Identification and structural validation of purine nucleoside phosphorylase from Plasmodium falciparum as a target of MMV000848. J Biol Chem 2024; 300:105586. [PMID: 38141766 PMCID: PMC10911062 DOI: 10.1016/j.jbc.2023.105586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 11/30/2023] [Accepted: 12/08/2023] [Indexed: 12/25/2023] Open
Abstract
About 247 million cases of malaria occurred in 2021 with Plasmodium falciparum accounting for the majority of 619,000 deaths. In the absence of a widely available vaccine, chemotherapy remains crucial to prevent, treat, and contain the disease. The efficacy of several drugs currently used in the clinic is likely to suffer from the emergence of resistant parasites. A global effort to identify lead compounds led to several initiatives such as the Medicine for Malaria Ventures (MMV), a repository of compounds showing promising efficacy in killing the parasite in cell-based assays. Here, we used mass spectrometry coupled with cellular thermal shift assay to identify putative protein targets of MMV000848, a compound with an in vitro EC50 of 0.5 μM against the parasite. Thermal shift assays showed a strong increase of P. falciparum purine nucleoside phosphorylase (PfPNP) melting temperature by up to 15 °C upon incubation with MMV000848. Binding and enzymatic assays returned a KD of 1.52 ± 0.495 μM and an IC50 value of 21.5 ± 2.36 μM. The inhibition is competitive with respect to the substrate, as confirmed by a cocrystal structure of PfPNP bound with MMV000848 at the active site, determined at 1.85 Å resolution. In contrast to transition states inhibitors, MMV000848 specifically inhibits the parasite enzyme but not the human ortholog. An isobologram analysis shows subadditivity with immucillin H and with quinine respectively, suggesting overlapping modes of action between these compounds. These results point to PfPNP as a promising antimalarial target and suggest avenues to improve inhibitor potency.
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Affiliation(s)
- Zara Chung
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore; NTU Institute of Structural Biology, Experimental Medicine Building (EMB), Nanyang Technological University, Singapore, Singapore
| | - Jianqing Lin
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore; NTU Institute of Structural Biology, Experimental Medicine Building (EMB), Nanyang Technological University, Singapore, Singapore
| | - Grennady Wirjanata
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Jerzy M Dziekan
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore
| | - Abbas El Sahili
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore; NTU Institute of Structural Biology, Experimental Medicine Building (EMB), Nanyang Technological University, Singapore, Singapore
| | - Peter R Preiser
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore; Antimicrobial Resistance Interdisciplinary Research Group, Singapore-MIT Alliance for Research and Technology Centre, Singapore, Singapore
| | - Zbynek Bozdech
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore; NTU Institute of Structural Biology, Experimental Medicine Building (EMB), Nanyang Technological University, Singapore, Singapore.
| | - Julien Lescar
- School of Biological Sciences, Nanyang Technological University, Singapore, Singapore; NTU Institute of Structural Biology, Experimental Medicine Building (EMB), Nanyang Technological University, Singapore, Singapore; Antimicrobial Resistance Interdisciplinary Research Group, Singapore-MIT Alliance for Research and Technology Centre, Singapore, Singapore.
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4
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Minnow YVT, Schramm VL, Almo SC, Ghosh A. Phosphate Binding in PNP Alters Transition-State Analogue Affinity and Subunit Cooperativity. Biochemistry 2023; 62:3116-3125. [PMID: 37812583 DOI: 10.1021/acs.biochem.3c00264] [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] [Indexed: 10/11/2023]
Abstract
Purine nucleoside phosphorylases (PNPs) catalyze the phosphorolysis of 6-oxypurine nucleosides with an HPO42- dianion nucleophile. Nucleosides and phosphate occupy distinct pockets in the PNP active site. Evaluation of the HPO42- site by mutagenesis, cooperative binding studies, and thermodynamic and structural analysis demonstrate that alterations in the HPO42- binding site can render PNP inactive and significantly impact subunit cooperativity and binding to transition-state analogue inhibitors. Cooperative interactions between the cationic transition-state analogue and the anionic HPO42- nucleophile demonstrate the importance of reforming the transition-state ensemble for optimal inhibition with transition-state analogues. Altered phosphate binding in the catalytic site mutants helps to explain one of the known lethal PNP deficiency syndromes in humans.
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Affiliation(s)
- Yacoba V T Minnow
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Vern L Schramm
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Steven C Almo
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
| | - Agnidipta Ghosh
- Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, United States
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5
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Jacewicz A, Dantuluri S, Shuman S. Structural basis for Tpt1-catalyzed 2'-PO 4 transfer from RNA and NADP(H) to NAD . Proc Natl Acad Sci U S A 2023; 120:e2312999120. [PMID: 37883434 PMCID: PMC10622864 DOI: 10.1073/pnas.2312999120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 09/14/2023] [Indexed: 10/28/2023] Open
Abstract
Tpt1 is an essential agent of fungal and plant tRNA splicing that removes an internal RNA 2'-phosphate generated by tRNA ligase. Tpt1 also removes the 2'-phosphouridine mark installed by Ark1 kinase in the V-loop of archaeal tRNAs. Tpt1 performs a two-step reaction in which the 2'-PO4 attacks NAD+ to form an RNA-2'-phospho-(ADP-ribose) intermediate, and transesterification of the ADP-ribose O2″ to the RNA 2'-phosphodiester yields 2'-OH RNA and ADP-ribose-1″,2″-cyclic phosphate. Here, we present structures of archaeal Tpt1 enzymes, captured as product complexes with ADP-ribose-1″-PO4, ADP-ribose-2″-PO4, and 2'-OH RNA, and as substrate complexes with 2',5'-ADP and NAD+, that illuminate 2'-PO4 junction recognition and catalysis. We show that archaeal Tpt1 enzymes can use the 2'-PO4-containing metabolites NADP+ and NADPH as substrates for 2'-PO4 transfer to NAD+. A role in 2'-phospho-NADP(H) dynamics provides a rationale for the prevalence of Tpt1 in taxa that lack a capacity for internal RNA 2'-phosphorylation.
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Affiliation(s)
- Agata Jacewicz
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY10065
| | - Swathi Dantuluri
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY10065
| | - Stewart Shuman
- Molecular Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY10065
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6
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Miller A, York EM, Stopka SA, Martínez-François JR, Hossain MA, Baquer G, Regan MS, Agar NYR, Yellen G. Spatially resolved metabolomics and isotope tracing reveal dynamic metabolic responses of dentate granule neurons with acute stimulation. Nat Metab 2023; 5:1820-1835. [PMID: 37798473 PMCID: PMC10626993 DOI: 10.1038/s42255-023-00890-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 08/09/2023] [Indexed: 10/07/2023]
Abstract
Neuronal activity creates an intense energy demand that must be met by rapid metabolic responses. To investigate metabolic adaptations in the neuron-enriched dentate granule cell (DGC) layer within its native tissue environment, we employed murine acute hippocampal brain slices, coupled with fast metabolite preservation and followed by mass spectrometry (MS) imaging, to generate spatially resolved metabolomics and isotope-tracing data. Here we show that membrane depolarization induces broad metabolic changes, including increased glycolytic activity in DGCs. Increased glucose metabolism in response to stimulation is accompanied by mobilization of endogenous inosine into pentose phosphates via the action of purine nucleotide phosphorylase (PNP). The PNP reaction is an integral part of the neuronal response to stimulation, because inhibition of PNP leaves DGCs energetically impaired during recovery from strong activation. Performing MS imaging on brain slices bridges the gap between live-cell physiology and the deep chemical analysis enabled by MS.
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Affiliation(s)
- Anne Miller
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
- Center for Pathobiochemistry and Genetics, Medical University of Vienna, Vienna, Austria
| | - Elisa M York
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Sylwia A Stopka
- Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | | | - Md Amin Hossain
- Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Gerard Baquer
- Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Michael S Regan
- Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Nathalie Y R Agar
- Department of Neurosurgery, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
- Department of Radiology, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
- Department of Cancer Biology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA, USA.
| | - Gary Yellen
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA.
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7
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Miller A, York E, Stopka S, Martínez-François J, Hossain MA, Baquer G, Regan M, Agar N, Yellen G. Spatially resolved metabolomics and isotope tracing reveal dynamic metabolic responses of dentate granule neurons with acute stimulation. RESEARCH SQUARE 2023:rs.3.rs-2276903. [PMID: 37546759 PMCID: PMC10402263 DOI: 10.21203/rs.3.rs-2276903/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Neuronal activity creates an intense energy demand that must be met by rapid metabolic responses. To investigate metabolic adaptations in the neuron-enriched dentate granule cell (DGC) layer within its native tissue environment, we employed murine acute hippocampal brain slices coupled with fast metabolite preservation, followed by mass spectrometry imaging (MALDI-MSI) to generate spatially resolved metabolomics and isotope tracing data. Here we show that membrane depolarization induces broad metabolic changes, including increased glycolytic activity in DGCs. Increased glucose metabolism in response to stimulation is accompanied by mobilization of endogenous inosine into pentose phosphates, via the action of purine nucleotide phosphorylase (PNP). The PNP reaction is an integral part of the neuronal response to stimulation, as inhibiting PNP leaves DGCs energetically impaired during recovery from strong activation. Performing MSI on brain slices bridges the gap between live cell physiology and the deep chemical analysis enabled by mass spectrometry.
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8
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SAXS Analysis and Characterization of Anticancer Activity of PNP-UDP Family Protein from Putranjiva roxburghii. Protein J 2022; 41:381-393. [PMID: 35674860 DOI: 10.1007/s10930-022-10060-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/29/2022] [Indexed: 10/18/2022]
Abstract
A class of plant defense and storage proteins, including Putranjiva roxburghii PNP protein (PRpnp), belongs to PNP-UDP family. The PRpnp and related plant proteins contain a disrupted PNP-UDP domain as revealed in previous studies. In PRpnp, the insert disrupting the domain contains the trypsin inhibitory site. In the present work, we analyzed native PRpnp (nPRpnp) complex formation with trypsin and inosine using SAXS experiments and established its dual functionality. Results indicated a relatively compact nPRpnp:Inosine structure, whereas trypsin complex showed conformational changes/flexibility. nPRpnp also exhibited a strong anti-cancer activity toward breast cancer (MCF-7), prostate cancer (DU-145) and hepatocellular carcinoma (HepG2) cell lines. MCF-7 and DU-145 were more sensitive to nPRpnp treatment as compared to HepG2. However, nPRpnp treatment showed no effect on the viability of HEK293 cells indicating that nPRpnp is specific for targeting the viability of only cancer cells. Further, acridine orange, DAPI and DNA fragmentation studies showed that cytotoxic effect of nPRpnp is mediated through induction of apoptosis as evident from the apoptosis-associated morphological changes and nuclear fragmentation observed after PRpnp treatment of cancer cells. These results suggest that PRpnp has the potential to be used as an anticancer agent. This is first report of anticancer activity as well as SAXS-based analysis for a PNP enzyme with trypsin inhibitory activity.
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9
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Kaspar F, Wolff DS, Neubauer P, Kurreck A, Arcus VL. pH-Independent Heat Capacity Changes during Phosphorolysis Catalyzed by the Pyrimidine Nucleoside Phosphorylase from Geobacillus thermoglucosidasius. Biochemistry 2021; 60:1573-1577. [PMID: 33955225 DOI: 10.1021/acs.biochem.1c00156] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Enzyme-catalyzed reactions sometimes display curvature in their Eyring plots in the absence of denaturation, indicative of a change in activation heat capacity. However, the effects of pH and (de)protonation on this phenomenon have remained unexplored. Herein, we report a kinetic characterization of the thermophilic pyrimidine nucleoside phosphorylase from Geobacillus thermoglucosidasius across a two-dimensional working space covering 35 °C and 3 pH units with two substrates displaying different pKa values. Our analysis revealed the presence of a measurable activation heat capacity change ΔCp⧧ in this reaction system, which showed no significant dependence on medium pH or substrate charge. Our results further describe the remarkable effects of a single halide substitution that has a minor influence on ΔCp⧧ but conveys a significant kinetic effect by decreasing the activation enthalpy, causing a >10-fold rate increase. Collectively, our results present an important piece in the understanding of enzymatic systems across multidimensional working spaces where the choice of reaction conditions can affect the rate, affinity, and thermodynamic phenomena independently of one another.
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Affiliation(s)
- Felix Kaspar
- Chair of Bioprocess Engineering, Institute of Biotechnology, Faculty III Process Sciences, Technische Universität Berlin, Straße des 17. Juni 135, D-10623 Berlin, Germany.,BioNukleo GmbH, Ackerstraße 76, D-13355 Berlin, Germany
| | - Darian S Wolff
- Chair of Bioprocess Engineering, Institute of Biotechnology, Faculty III Process Sciences, Technische Universität Berlin, Straße des 17. Juni 135, D-10623 Berlin, Germany
| | - Peter Neubauer
- Chair of Bioprocess Engineering, Institute of Biotechnology, Faculty III Process Sciences, Technische Universität Berlin, Straße des 17. Juni 135, D-10623 Berlin, Germany
| | - Anke Kurreck
- Chair of Bioprocess Engineering, Institute of Biotechnology, Faculty III Process Sciences, Technische Universität Berlin, Straße des 17. Juni 135, D-10623 Berlin, Germany.,BioNukleo GmbH, Ackerstraße 76, D-13355 Berlin, Germany
| | - Vickery L Arcus
- Te Aka Ma̅tuatua-School of Science, Te Whare Wa̅nanga o Waikato-University of Waikato, Hamilton 3240, New Zealand
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10
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Alphonse S, Banerjee A, Dantuluri S, Shuman S, Ghose R. NMR solution structures of Runella slithyformis RNA 2'-phosphotransferase Tpt1 provide insights into NAD+ binding and specificity. Nucleic Acids Res 2021; 49:9607-9624. [PMID: 33880546 PMCID: PMC8464070 DOI: 10.1093/nar/gkab241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 03/16/2021] [Accepted: 03/23/2021] [Indexed: 11/18/2022] Open
Abstract
Tpt1, an essential component of the fungal and plant tRNA splicing machinery, catalyzes transfer of an internal RNA 2′-PO4 to NAD+ yielding RNA 2′-OH and ADP-ribose-1′,2′-cyclic phosphate products. Here, we report NMR structures of the Tpt1 ortholog from the bacterium Runella slithyformis (RslTpt1), as apoenzyme and bound to NAD+. RslTpt1 consists of N- and C-terminal lobes with substantial inter-lobe dynamics in the free and NAD+-bound states. ITC measurements of RslTpt1 binding to NAD+ (KD ∼31 μM), ADP-ribose (∼96 μM) and ADP (∼123 μM) indicate that substrate affinity is determined primarily by the ADP moiety; no binding of NMN or nicotinamide is observed by ITC. NAD+-induced chemical shift perturbations (CSPs) localize exclusively to the RslTpt1 C-lobe. NADP+, which contains an adenylate 2′-PO4 (mimicking the substrate RNA 2′-PO4), binds with lower affinity (KD ∼1 mM) and elicits only N-lobe CSPs. The RslTpt1·NAD+ binary complex reveals C-lobe contacts to adenosine ribose hydroxyls (His99, Thr101), the adenine nucleobase (Asn105, Asp112, Gly113, Met117) and the nicotinamide riboside (Ser125, Gln126, Asn163, Val165), several of which are essential for RslTpt1 activity in vivo. Proximity of the NAD+ β-phosphate to ribose-C1″ suggests that it may stabilize an oxocarbenium transition-state during the first step of the Tpt1-catalyzed reaction.
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Affiliation(s)
- Sébastien Alphonse
- Department of Chemistry and Biochemistry, The City College of New York, New York, NY 10031, USA
| | - Ankan Banerjee
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10021, USA
| | - Swathi Dantuluri
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10021, USA
| | - Stewart Shuman
- Molecular Biology Program, Sloan-Kettering Institute, New York, NY 10021, USA
| | - Ranajeet Ghose
- Department of Chemistry and Biochemistry, The City College of New York, New York, NY 10031, USA.,Graduate Program in Chemistry, The Graduate Center of CUNY, New York, NY 10016, USA.,Graduate Program in Biochemistry, The Graduate Center of CUNY, New York, NY 10016, USA.,Graduate Program in Physics, The Graduate Center of CUNY, New York, NY 10016, USA
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11
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Spöring M, Boneberg R, Hartig JS. Aptamer-Mediated Control of Polyadenylation for Gene Expression Regulation in Mammalian Cells. ACS Synth Biol 2020; 9:3008-3018. [PMID: 33108164 DOI: 10.1021/acssynbio.0c00222] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Small aptamer-based regulatory devices can be designed to control a range of RNA-dependent cellular processes and emerged as promising tools for fine-tuning gene expression in synthetic biology. Here, we design a conceptually new riboswitch device that allows for the conditional regulation of polyadenylation. By making use of ligand-induced sequence occlusion, the system efficiently controls the accessibility of the eukaryotic polyadenylation signal. Undesirable 3'-extended read-through products are counteracted by the downstream insertion of a microRNA target site. We demonstrate the modularity of the system with regard to sensor aptamers and polyadenylation signals used and combine the newly designed riboswitch with well-known aptazymes to yield superior composite systems. In addition, we show that the switches can be used to control alternative polyadenylation. The presented genetic switches require very little coding space and can be easily optimized by rational adjustments of the thermodynamic stability. The polyadenylation riboswitch extends the repertoire of RNA-based regulators and opens new possibilities for the generation of complex synthetic circuits.
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Affiliation(s)
- Maike Spöring
- Department of Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
- Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Ronja Boneberg
- Department of Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
| | - Jörg S. Hartig
- Department of Chemistry, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
- Konstanz Research School Chemical Biology, University of Konstanz, Universitätsstraße 10, 78457 Konstanz, Germany
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12
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Chen K, Pei D. Engineering Cell-Permeable Proteins through Insertion of Cell-Penetrating Motifs into Surface Loops. ACS Chem Biol 2020; 15:2568-2576. [PMID: 32786266 DOI: 10.1021/acschembio.0c00593] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Effective delivery of proteins into the cytosol of mammalian cells would open the door to a wide range of applications. However, despite great efforts from numerous investigators, effective protein delivery in a clinical setting is yet to be accomplished. Herein we report a potentially general approach to engineering cell-permeable proteins by genetically grafting a short cell-penetrating peptide (CPP) to an exposed loop of a protein of interest. The grafted peptide is conformationally constrained, exhibiting enhanced proteolytic stability and cellular entry efficiency. Applying this technique to enhanced green fluorescent protein (EGFP), protein-tyrosine phosphatase 1B (PTP1B), and purine nucleoside phosphorylase (PNP) rendered all three proteins cell-permeable and biologically active in cellular assays. When added into growth medium at 0.5-5 μM concentrations, the engineered PTP1B dose-dependently reduced the phosphotyrosine levels of intracellular proteins, while the modified PNP corrected the metabolic deficiency of PNP-deficient mouse T lymphocytes, providing a potential enzyme replacement therapy for a rare genetic disease.
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Affiliation(s)
- Kuangyu Chen
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Dehua Pei
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
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13
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Grunebaum E, Campbell N, Leon-Ponte M, Xu X, Chapdelaine H. Partial Purine Nucleoside Phosphorylase Deficiency Helps Determine Minimal Activity Required for Immune and Neurological Development. Front Immunol 2020; 11:1257. [PMID: 32695102 PMCID: PMC7338719 DOI: 10.3389/fimmu.2020.01257] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 05/18/2020] [Indexed: 11/13/2022] Open
Abstract
Introduction: Complete or near complete absence of the purine nucleoside phosphorylase (PNP) enzyme causes a profound T cell immunodeficiency and neurological abnormalities that are often lethal in infancy and early childhood. We hypothesized that patients with partial PNP deficiency, characterized by a late and mild phenotype due to residual PNP enzyme, would provide important information about the minimal PNP activity needed for normal development. Methods: Three siblings with a homozygous PNP gene mutation (c.769C>G, p.His257Asp) resulting in partial PNP deficiency were investigated. PNP activity was semi-quantitively assayed by the conversion of [14C]inosine in hemolysates, mononuclear cells, and lymphoblastoid B cells. PNP protein expression was determined by Western Blotting in lymphoblastoid B cells. DNA repair was quantified by measuring viability of lymphoblastoid B cells following ionizing irradiation. Results: A 21-year-old female was referred for recurrent sino-pulmonary infections while her older male siblings, aged 25- and 28- years, did not suffer from significant infections. Two of the siblings had moderately reduced numbers of T, B, and NK cells, while the other had near normal lymphocyte subset numbers. T cell proliferations were normal in the two siblings tested. Hypogammaglobulinemia was noted in two siblings, including one that required immunoglobulin replacement. All siblings had typical (normal) neurological development. PNP activity in various cells from two patients were 8-11% of the normal level. All siblings had normal blood uric acid and increased PNP substrates in the urine. PNP protein expression in cells from the two patients examined was similar to that observed in cells from healthy controls. The survival of lymphoblastoid B cells from 2 partial PNP-deficient patients after irradiation was similar to that of PNP-proficient cells and markedly higher than the survival of cells from a patient with absent PNP activity or a patient with ataxia telangiectasia. Conclusions: Patients with partial PNP deficiency can present in the third decade of life with mild-moderate immune abnormalities and typical development. Near-normal immunity might be achieved with relatively low PNP activity.
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Affiliation(s)
- Eyal Grunebaum
- Division of Immunology and Allergy, Hospital for Sick Children, Toronto, ON, Canada.,Developmental and Stem Cell Biology Program, Hospital for Sick Children, Toronto, ON, Canada
| | - Nicholas Campbell
- Department of Medicine, Centre Hospitalier de I'Universite de Montreal, and Montreal Clinical Research Institute, Montreal, QC, Canada
| | - Matilde Leon-Ponte
- Developmental and Stem Cell Biology Program, Hospital for Sick Children, Toronto, ON, Canada
| | - Xiaobai Xu
- Developmental and Stem Cell Biology Program, Hospital for Sick Children, Toronto, ON, Canada
| | - Hugo Chapdelaine
- Department of Medicine, Centre Hospitalier de I'Universite de Montreal, and Montreal Clinical Research Institute, Montreal, QC, Canada
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14
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Dorababu A. Evolution of uracil based thymidine phosphorylase inhibitors, SAR and electronic correlation: revisit. Drug Dev Res 2019. [DOI: 10.1002/ddr.21592] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Atukuri Dorababu
- Department of Studies in ChemistrySRMPP Govt. First Grade College Huvinahadagali Karnataka India
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15
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Torini JR, Romanello L, Batista FAH, Serrão VHB, Faheem M, Zeraik AE, Bird L, Nettleship J, Reddivari Y, Owens R, DeMarco R, Borges JC, Brandão-Neto J, Pereira HD. The molecular structure of Schistosoma mansoni PNP isoform 2 provides insights into the nucleoside selectivity of PNPs. PLoS One 2018; 13:e0203532. [PMID: 30192840 PMCID: PMC6128611 DOI: 10.1371/journal.pone.0203532] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 08/22/2018] [Indexed: 12/16/2022] Open
Abstract
Purine nucleoside phosphorylases (PNPs) play an important role in the blood fluke parasite Schistosoma mansoni as a key enzyme of the purine salvage pathway. Here we present the structural and kinetic characterization of a new PNP isoform from S. mansoni, SmPNP2. Thermofluorescence screening of different ligands suggested cytidine and cytosine are potential ligands. The binding of cytosine and cytidine were confirmed by isothermal titration calorimetry, with a KD of 27 μM for cytosine, and a KM of 76.3 μM for cytidine. SmPNP2 also displays catalytic activity against inosine and adenosine, making it the first described PNP with robust catalytic activity towards both pyrimidines and purines. Crystal structures of SmPNP2 with different ligands were obtained and comparison of these structures with the previously described S. mansoni PNP (SmPNP1) provided clues for the unique capacity of SmPNP2 to bind pyrimidines. When compared with the structure of SmPNP1, substitutions in the vicinity of SmPNP2 active site alter the architecture of the nucleoside base binding site thus permitting an alternative binding mode for nucleosides, with a 180° rotation from the canonical binding mode. The remarkable plasticity of this binding site enhances our understanding of the correlation between structure and nucleotide selectivity, thus suggesting new ways to analyse PNP activity.
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Affiliation(s)
- Juliana Roberta Torini
- Laboratório de Biologia Estrutural, Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brazil
| | - Larissa Romanello
- Laboratório de Biologia Estrutural, Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brazil
| | - Fernanda Aparecida Heleno Batista
- Instituto de Química de São Carlos, Universidade de São Paulo - USP, São Carlos, São Paulo, Brazil
- Centro Nacional de Pesquisa em Energia e Materiais, Laboratório Nacional de Biociências, Campinas, São Paulo, Brazil
| | - Vitor Hugo Balasco Serrão
- Laboratório de Biologia Estrutural, Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brazil
| | - Muhammad Faheem
- Programa de Pós Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília, Federal District, Brazil
- Laboratório de Biofísica Molecular, Departamento de Biologia Celular, Universidade de Brasília, Brasília, Federal District, Brazil
| | - Ana Eliza Zeraik
- Laboratório de Biologia Estrutural, Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brazil
| | - Louise Bird
- OPPF-UK, Research Complex at Harwell, Rutherford Appleton Laboratory, Oxford, United Kingdom
| | - Joanne Nettleship
- OPPF-UK, Research Complex at Harwell, Rutherford Appleton Laboratory, Oxford, United Kingdom
| | - Yamini Reddivari
- OPPF-UK, Research Complex at Harwell, Rutherford Appleton Laboratory, Oxford, United Kingdom
| | - Ray Owens
- OPPF-UK, Research Complex at Harwell, Rutherford Appleton Laboratory, Oxford, United Kingdom
| | - Ricardo DeMarco
- Laboratório de Biologia Estrutural, Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brazil
| | - Júlio César Borges
- Instituto de Química de São Carlos, Universidade de São Paulo - USP, São Carlos, São Paulo, Brazil
| | - José Brandão-Neto
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, United Kingdom
| | - Humberto D’Muniz Pereira
- Laboratório de Biologia Estrutural, Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brazil
- * E-mail:
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16
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Timofeev VI, Zhukhlistova NE, Abramchik YA, Muravieva TI, Esipov RS, Kuranova IP. Crystal structure of Escherichia coli purine nucleoside phosphorylase complexed with acyclovir. Acta Crystallogr F Struct Biol Commun 2018; 74:402-409. [PMID: 29969103 PMCID: PMC6038453 DOI: 10.1107/s2053230x18008087] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 05/31/2018] [Indexed: 11/10/2022] Open
Abstract
Escherichia coli purine nucleoside phosphorylase (PNP), which catalyzes the reversible phosphorolysis of purine ribonucleosides, belongs to the family I hexameric PNPs. Owing to their key role in the purine salvage pathway, PNPs are attractive targets for drug design against some pathogens. Acyclovir (ACV) is an acyclic derivative of the PNP substrate guanosine and is used as an antiviral drug for the treatment of some human viral infections. The crystalline complex of E. coli PNP with acyclovir was prepared by co-crystallization in microgravity using counter-diffusion through a gel layer in a capillary. The structure of the E. coli PNP-ACV complex was solved at 2.32 Å resolution using the molecular-replacement method. The ACV molecule is observed in two conformations and sulfate ions were located in both the nucleoside-binding and phosphate-binding pockets of the enzyme. A comparison with the complexes of other hexameric and trimeric PNPs with ACV shows the similarity in acyclovir binding by these enzymes.
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Affiliation(s)
- Vladimir I. Timofeev
- Shubnikov Institute of Crystallography, Federal Scientific Research Centre ‘Crystallography and Photonics’ of Russian Academy of Sciences, Leninsky Prospekt 59, Moscow 119333, Russian Federation
- Kurchatov Complex of NBICS-Technologies, National Research Center ‘Kurchatov Institute’, Akad. Kurchatova Square 1, Moscow 123182, Russian Federation
| | - Nadezhda E. Zhukhlistova
- Shubnikov Institute of Crystallography, Federal Scientific Research Centre ‘Crystallography and Photonics’ of Russian Academy of Sciences, Leninsky Prospekt 59, Moscow 119333, Russian Federation
| | - Yuliya A. Abramchik
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation
| | - Tatiana I. Muravieva
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation
| | - Roman S. Esipov
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation
| | - Inna P. Kuranova
- Shubnikov Institute of Crystallography, Federal Scientific Research Centre ‘Crystallography and Photonics’ of Russian Academy of Sciences, Leninsky Prospekt 59, Moscow 119333, Russian Federation
- Kurchatov Complex of NBICS-Technologies, National Research Center ‘Kurchatov Institute’, Akad. Kurchatova Square 1, Moscow 123182, Russian Federation
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17
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Timofeev VI, Zhukhlistova NE, Abramchik YA, Fateev II, Kostromina MA, Muravieva TI, Esipov RS, Kuranova IP. Crystal structure of Escherichia coli purine nucleoside phosphorylase in complex with 7-deazahypoxanthine. Acta Crystallogr F Struct Biol Commun 2018; 74:355-362. [PMID: 29870020 PMCID: PMC5987744 DOI: 10.1107/s2053230x18006337] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 04/25/2018] [Indexed: 11/10/2022] Open
Abstract
Purine nucleoside phosphorylases (EC 2.4.2.1; PNPs) reversibly catalyze the phosphorolytic cleavage of glycosidic bonds in purine nucleosides to generate ribose 1-phosphate and a free purine base, and are key enzymes in the salvage pathway of purine biosynthesis. They also catalyze the transfer of pentosyl groups between purine bases (the transglycosylation reaction) and are widely used for the synthesis of biologically important analogues of natural nucleosides, including a number of anticancer and antiviral drugs. Potent inhibitors of PNPs are used in chemotherapeutic applications. The detailed study of the binding of purine bases and their derivatives in the active site of PNPs is of particular interest in order to understand the mechanism of enzyme action and for the development of new enzyme inhibitors. Here, it is shown that 7-deazahypoxanthine (7DHX) is a noncompetitive inhibitor of the phosphorolysis of inosine by recombinant Escherichia coli PNP (EcPNP) with an inhibition constant Ki of 0.13 mM. A crystal of EcPNP in complex with 7DHX was obtained in microgravity by the counter-diffusion technique and the three-dimensional structure of the EcPNP-7DHX complex was solved by molecular replacement at 2.51 Å resolution using an X-ray data set collected at the SPring-8 synchrotron-radiation facility, Japan. The crystals belonged to space group P6122, with unit-cell parameters a = b = 120.370, c = 238.971 Å, and contained three subunits of the hexameric enzyme molecule in the asymmetric unit. The 7DHX molecule was located with full occupancy in the active site of each of the three crystallographically independent enzyme subunits. The position of 7DHX overlapped with the positions occupied by purine bases in similar PNP complexes. However, the orientation of the 7DHX molecule differs from those of other bases: it is rotated by ∼180° relative to other bases. The peculiarities of the arrangement of 7DHX in the EcPNP active site are discussed.
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Affiliation(s)
- Vladimir I. Timofeev
- Shubnikov Institute of Crystallography, Federal Scientific Research Centre ‘Crystallography and Photonics’ of Russian Academy of Sciences, Leninsky Prospekt 59, Moscow 119333, Russian Federation
- Kurchatov Complex of NBICS-Technologies, National Research Center ‘Kurchatov Institute’, Akad. Kurchatova Square 1, Moscow 123182, Russian Federation
| | - Nadezhda E. Zhukhlistova
- Shubnikov Institute of Crystallography, Federal Scientific Research Centre ‘Crystallography and Photonics’ of Russian Academy of Sciences, Leninsky Prospekt 59, Moscow 119333, Russian Federation
| | - Yuliya A. Abramchik
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation
| | - Ilya I. Fateev
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation
| | - Maria A. Kostromina
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation
| | - Tatiana I. Muravieva
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation
| | - Roman S. Esipov
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Miklukho-Maklaya Street 16/10, Moscow 117997, Russian Federation
| | - Inna P. Kuranova
- Shubnikov Institute of Crystallography, Federal Scientific Research Centre ‘Crystallography and Photonics’ of Russian Academy of Sciences, Leninsky Prospekt 59, Moscow 119333, Russian Federation
- Kurchatov Complex of NBICS-Technologies, National Research Center ‘Kurchatov Institute’, Akad. Kurchatova Square 1, Moscow 123182, Russian Federation
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18
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A synergistic effect of phosphate, pH and Phe159 substitution on the formycin A association to the E. coli purine nucleoside phosphorylase. Biochimie 2018; 148:80-86. [DOI: 10.1016/j.biochi.2018.02.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2017] [Accepted: 02/22/2018] [Indexed: 11/22/2022]
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19
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Isaksen GV, Åqvist J, Brandsdal BO. Thermodynamics of the Purine Nucleoside Phosphorylase Reaction Revealed by Computer Simulations. Biochemistry 2016; 56:306-312. [DOI: 10.1021/acs.biochem.6b00967] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Geir Villy Isaksen
- The
Centre for Theoretical and Computational Chemistry, Department of
Chemistry, University of Tromsø, NO-9037 Tromsø, Norway
| | - Johan Åqvist
- Department
of Cell and Molecular Biology, Biomedical Center, Uppsala University, SE-75124 Uppsala, Sweden
| | - Bjørn Olav Brandsdal
- The
Centre for Theoretical and Computational Chemistry, Department of
Chemistry, University of Tromsø, NO-9037 Tromsø, Norway
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20
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Functional and Structural Characterization of Purine Nucleoside Phosphorylase from Kluyveromyces lactis and Its Potential Applications in Reducing Purine Content in Food. PLoS One 2016; 11:e0164279. [PMID: 27768715 PMCID: PMC5074518 DOI: 10.1371/journal.pone.0164279] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 09/22/2016] [Indexed: 01/19/2023] Open
Abstract
Consumption of foods and beverages with high purine content increases the risk of hyperuricemia, which causes gout and can lead to cardiovascular, renal, and other metabolic disorders. As patients often find dietary restrictions challenging, enzymatically lowering purine content in popular foods and beverages offers a safe and attractive strategy to control hyperuricemia. Here, we report structurally and functionally characterized purine nucleoside phosphorylase (PNP) from Kluyveromyces lactis (KlacPNP), a key enzyme involved in the purine degradation pathway. We report a 1.97 Å resolution crystal structure of homotrimeric KlacPNP with an intrinsically bound hypoxanthine in the active site. KlacPNP belongs to the nucleoside phosphorylase-I (NP-I) family, and it specifically utilizes 6-oxopurine substrates in the following order: inosine > guanosine > xanthosine, but is inactive towards adenosine. To engineer enzymes with broad substrate specificity, we created two point variants, KlacPNPN256D and KlacPNPN256E, by replacing the catalytically active Asn256 with Asp and Glu, respectively, based on structural and comparative sequence analysis. KlacPNPN256D not only displayed broad substrate specificity by utilizing both 6-oxopurines and 6-aminopurines in the order adenosine > inosine > xanthosine > guanosine, but also displayed reversal of substrate specificity. In contrast, KlacPNPN256E was highly specific to inosine and could not utilize other tested substrates. Beer consumption is associated with increased risk of developing gout, owing to its high purine content. Here, we demonstrate that KlacPNP and KlacPNPN256D could be used to catalyze a key reaction involved in lowering beer purine content. Biochemical properties of these enzymes such as activity across a wide pH range, optimum activity at about 25°C, and stability for months at about 8°C, make them suitable candidates for food and beverage industries. Since KlacPNPN256D has broad substrate specificity, a combination of engineered KlacPNP and other enzymes involved in purine degradation could effectively lower the purine content in foods and beverages.
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21
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Hohn C, Härtsch A, Ehrmann FR, Pfaffeneder T, Trapp N, Dumele O, Klebe G, Diederich F. An Immucillin-Based Transition-State-Analogous Inhibitor of tRNA-Guanine Transglycosylase (TGT). Chemistry 2016; 22:6750-4. [PMID: 26991861 DOI: 10.1002/chem.201600883] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Indexed: 11/06/2022]
Abstract
Shigellosis is one of the most severe diarrheal diseases worldwide without any efficient treatment so far. The enzyme tRNA-guanine transglycosylase (TGT) has been identified as a promising target for small-molecule drug design. Herein, we report a transition-state analogue, a small, immucillin-derived inhibitor, as a new lead structure with a novel mode of action. The complex inhibitor synthesis was accomplished in 18 steps with an overall yield of 3 %. A co-crystal structure of the inhibitor bound to Z. mobilis TGT confirmed the predicted conformation of the immucillin derivative in the enzyme active site.
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Affiliation(s)
- Christoph Hohn
- Laboratorium für Organische Chemie, ETH Zurich, Vladimir-Prelog-Weg 3, HCI, 8093, Zurich, Switzerland
| | - Adrian Härtsch
- Laboratorium für Organische Chemie, ETH Zurich, Vladimir-Prelog-Weg 3, HCI, 8093, Zurich, Switzerland
| | - Frederik Rainer Ehrmann
- Institut für Pharmazeutische Chemie, Philipps Universität Marburg, Marbacher Weg 6, 35032, Marburg, Germany
| | - Toni Pfaffeneder
- Laboratorium für Organische Chemie, ETH Zurich, Vladimir-Prelog-Weg 3, HCI, 8093, Zurich, Switzerland
| | - Nils Trapp
- Laboratorium für Organische Chemie, ETH Zurich, Vladimir-Prelog-Weg 3, HCI, 8093, Zurich, Switzerland
| | - Oliver Dumele
- Laboratorium für Organische Chemie, ETH Zurich, Vladimir-Prelog-Weg 3, HCI, 8093, Zurich, Switzerland
| | - Gerhard Klebe
- Institut für Pharmazeutische Chemie, Philipps Universität Marburg, Marbacher Weg 6, 35032, Marburg, Germany.
| | - François Diederich
- Laboratorium für Organische Chemie, ETH Zurich, Vladimir-Prelog-Weg 3, HCI, 8093, Zurich, Switzerland.
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22
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Isaksen GV, Hopmann KH, Åqvist J, Brandsdal BO. Computer Simulations Reveal Substrate Specificity of Glycosidic Bond Cleavage in Native and Mutant Human Purine Nucleoside Phosphorylase. Biochemistry 2016; 55:2153-62. [PMID: 26985580 DOI: 10.1021/acs.biochem.5b01347] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Purine nucleoside phosphorylase (PNP) catalyzes the reversible phosphorolysis of purine ribonucleosides and 2'-deoxyribonucleosides, yielding the purine base and (2'-deoxy)ribose 1-phosphate as products. While this enzyme has been extensively studied, several questions with respect to the catalytic mechanism have remained largely unanswered. The role of the phosphate and key amino acid residues in the catalytic reaction as well as the purine ring protonation state is elucidated using density functional theory calculations and extensive empirical valence bond (EVB) simulations. Free energy surfaces for adenosine, inosine, and guanosine are fitted to ab initio data and yield quantitative agreement with experimental data when the surfaces are used to model the corresponding enzymatic reactions. The cognate substrates 6-aminopurines (inosine and guanosine) interact with PNP through extensive hydrogen bonding, but the substrate specificity is found to be a direct result of the electrostatic preorganization energy along the reaction coordinate. Asn243 has previously been identified as a key residue providing substrate specificity. Mutation of Asn243 to Asp has dramatic effects on the substrate specificity, making 6-amino- and 6-oxopurines equally good as substrates. The principal effect of this particular mutation is the change in the electrostatic preorganization energy between the native enzyme and the Asn243Asp mutant, clearly favoring adenosine over inosine and guanosine. Thus, the EVB simulations show that this particular mutation affects the electrostatic preorganization of the active site, which in turn can explain the substrate specificity.
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Affiliation(s)
- Geir Villy Isaksen
- Centre for Theoretical and Computational Chemistry, Department of Chemistry, Faculty of Science and Technology, University of Tromsø , N9037 Tromsø, Norway
| | - Kathrin Helen Hopmann
- Centre for Theoretical and Computational Chemistry, Department of Chemistry, Faculty of Science and Technology, University of Tromsø , N9037 Tromsø, Norway
| | - Johan Åqvist
- Department of Cell & Molecular Biology, Uppsala University , SE-75124 Uppsala, Sweden
| | - Bjørn Olav Brandsdal
- Centre for Theoretical and Computational Chemistry, Department of Chemistry, Faculty of Science and Technology, University of Tromsø , N9037 Tromsø, Norway
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23
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Fateev IV, Kharitonova MI, Antonov KV, Konstantinova ID, Stepanenko VN, Esipov RS, Seela F, Temburnikar KW, Seley-Radtke KL, Stepchenko VA, Sokolov YA, Miroshnikov AI, Mikhailopulo IA. Recognition of Artificial Nucleobases byE. coliPurine Nucleoside Phosphorylase versus its Ser90Ala Mutant in the Synthesis of Base-Modified Nucleosides. Chemistry 2015; 21:13401-19. [DOI: 10.1002/chem.201501334] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2015] [Indexed: 01/17/2023]
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24
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Wierzchowski J, Antosiewicz JM, Shugar D. 8-Azapurines as isosteric purine fluorescent probes for nucleic acid and enzymatic research. MOLECULAR BIOSYSTEMS 2015; 10:2756-74. [PMID: 25124808 DOI: 10.1039/c4mb00233d] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
The 8-azapurines, and their 7-deaza and 9-deaza congeners, represent a unique class of isosteric (isomorphic) analogues of the natural purines, frequently capable of substituting for the latter in many biochemical processes. Particularly interesting is their propensity to exhibit pH-dependent room-temperature fluorescence in aqueous medium, and in non-polar media. We herein review the physico-chemical properties of this class of compounds, with particular emphasis on the fluorescence emission properties of their neutral and/or ionic species, which has led to their widespread use as fluorescent probes in enzymology, including enzymes involved in purine metabolism, agonists/antagonists of adenosine receptors, mechanisms of catalytic RNAs, RNA editing, etc. They are also exceptionally useful fluorescent probes for analytical and clinical applications in crude cell homogenates.
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Affiliation(s)
- Jacek Wierzchowski
- Department of Biophysics, University of Varmia & Masuria, Oczapowskiego 4, 10-719 Olsztyn, Poland.
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25
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Rivero CW, De Benedetti EC, Lozano ME, Trelles JA. Bioproduction of ribavirin by green microbial biotransformation. Process Biochem 2015; 50:935-940. [PMID: 32288593 PMCID: PMC7108421 DOI: 10.1016/j.procbio.2015.03.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 03/16/2015] [Indexed: 11/24/2022]
Abstract
Biotransformation of ribavirin was performed by E. coli ATCC 12407, reaching yields of 86%. This mesophile microorganism was successfully stabilized in agarose and polyacrylamide. Biocatalyst immobilized in agarose could be reused during 270 h without activity loss. Packed-bed bioreactor prototype was able to produce 95 mg ribavirin.
Ribavirin is an antiviral compound widely used in Hepatitis C Virus therapy. Biotransformation of this nucleoside analogue using Escherichia coli ATCC 12407 as biocatalyst is herein reported. Reaction parameters such as microorganism amounts, substrate ratio and temperature were optimized reaching conversion yields of 86%. Biocatalyst stability was enhanced by immobilization in agarose matrix. This immobilized biocatalyst was able to be reused for more than 270 h and could be stored during more than 4 months without activity loss. Batch and packed-bed reactors based on a stabilized biocatalyst were assayed for bioprocess scale-up. A continuous sustainable bioprocess was evaluated using a prototype packed-bed reactor, which allowed to produce 95 mg of ribavirin. Finally, in this work an efficient green bioprocess for ribavirin bioproduction using a stabilized biocatalyst was developed.
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Affiliation(s)
- Cintia W Rivero
- Laboratorio de Investigaciones en Biotecnología Sustentable (LIBioS), Universidad Nacional de Quilmes, Roque Sáenz Peña 352, Bernal (B1876BXD), Argentina
| | - Eliana C De Benedetti
- Laboratorio de Investigaciones en Biotecnología Sustentable (LIBioS), Universidad Nacional de Quilmes, Roque Sáenz Peña 352, Bernal (B1876BXD), Argentina
| | - Mario E Lozano
- Laboratorio de Investigaciones en Biotecnología Sustentable (LIBioS), Universidad Nacional de Quilmes, Roque Sáenz Peña 352, Bernal (B1876BXD), Argentina
| | - Jorge A Trelles
- Laboratorio de Investigaciones en Biotecnología Sustentable (LIBioS), Universidad Nacional de Quilmes, Roque Sáenz Peña 352, Bernal (B1876BXD), Argentina
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Safonova TN, Mikhailov SN, Veiko VP, Mordkovich NN, Manuvera VA, Alekseev CS, Kovalchuk MV, Popov VO, Polyakov KM. High-synconformation of uridine and asymmetry of the hexameric molecule revealed in the high-resolution structures ofShewanella oneidensisMR-1 uridine phosphorylase in the free form and in complex with uridine. ACTA ACUST UNITED AC 2014; 70:3310-9. [DOI: 10.1107/s1399004714024079] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 10/31/2014] [Indexed: 11/10/2022]
Abstract
Uridine phosphorylase (UP; EC 2.4.2.3), a key enzyme in the pyrimidine-salvage pathway, catalyzes the reversible phosphorolysis of uridine to uracil and ribose 1-phosphate. Expression of UP fromShewanella oneidensisMR-1 (SoUP) was performed inEscherichia coli. The high-resolution X-ray structure of SoUP was solved in the free form and in complex with uridine. A crystal of SoUP in the free form was grown under microgravity and diffracted to ultrahigh resolution. Both forms of SoUP contained sulfate instead of phosphate in the active site owing to the presence of ammonium sulfate in the crystallization solution. The latter can be considered as a good mimic of phosphate. In the complex, uridine adopts a high-synconformation with a nearly planar ribose ring and is present only in one subunit of the hexamer. A comparison of the structures of SoUP in the free form and in complex with the natural substrate uridine showed that the subunits of the hexamer are not identical, with the active sites having either an open or a closed conformation. In the monomers with the closed conformation, the active sites in which uridine is absent contain a glycerol molecule mimicking the ribose moiety of uridine.
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27
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Affiliation(s)
- David S Barnett
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital , Memphis, Tennessee 38105, United States
| | - R Kiplin Guy
- Department of Chemical Biology and Therapeutics, St. Jude Children's Research Hospital , Memphis, Tennessee 38105, United States
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28
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Kang X, Zhao Y, Jiang D, Li X, Wang X, Wu Y, Chen Z, Zhang XC. Crystal structure and biochemical studies of Brucella melitensis 5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase. Biochem Biophys Res Commun 2014; 446:965-70. [PMID: 24657441 DOI: 10.1016/j.bbrc.2014.03.045] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 03/11/2014] [Indexed: 11/29/2022]
Abstract
The prokaryotic 5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTAN) catalyzes the irreversible cleavage of the glycosidic bond in 5'-methylthioadenosine (MTA) and S-adenosylhomocysteine (SAH), a process that plays a key role in several metabolic pathways. Its absence in all mammalian species has implicated this enzyme as a promising target for antimicrobial drug design. Here, we report the crystal structure of BmMTAN in complex with its product adenine at a resolution of 2.6 Å determined by single-wavelength anomalous dispersion method. 11 key residues were mutated for kinetic characterization. Mutations of Tyr134 and Met144 resulted in the largest overall increase in Km, whereas mutagenesis of residues Glu18, Glu145 and Asp168 completely abolished activity. Glu145 and Asp168 were identified as active site residues essential for catalysis. The catalytic mechanism and implications of this structure for broad-based antibiotic design are discussed.
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Affiliation(s)
- Xusheng Kang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yan Zhao
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Daohua Jiang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Xuemei Li
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Xianping Wang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
| | - Yan Wu
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China; Food Science and Engineering College, Beijing University of Agriculture, Beijing 102206, China
| | - Zeliang Chen
- Department of Infectious Disease Control, Institute of Disease Control and Prevention, Academy of Military Medical Sciences, Beijing 100071, China
| | - Xuejun C Zhang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
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Abstract
Purine nucleoside phosphorylase (PNP) is one of the most important enzymes of the purine metabolism, wich promotes the recycling of purine bases. Nowadays is the actual to search for effective inhibitors of this enzyme which is necessary for creation T-cell immunodeficient status of the organism in the organs and tissues transplantation, and chemotherapy of a number pathologies as well. For their successful practical application necessary to conduct in-depth and comprehensive study of the enzyme, namely a structure, functions, and an affinity of the reaction mechanism. In the review the contemporary achievements in the study of PNP from various biological objects are presented. New data describing the structure of PNP are summarised and analysed. The physiological role of the enzyme is discussed. The enzyme basic reaction mechanisms and actions are considered. The studies on enzyme physicochemical, kinetic, and catalytic research are presented.
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Affiliation(s)
- Katarzyna Swiderek
- Institute of Applied Radiation Chemistry, Faculty of Chemistry, Lodz University of Technology , Zeromskiego 116, 90-924 Lodz, Poland
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31
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Barnett CB, Naidoo KJ. PNP diminishes guanosine glycosidic bond strength through restrictive ring pucker as a precursor to phosphorylation. J Phys Chem B 2013; 117:6019-26. [PMID: 23621450 DOI: 10.1021/jp3109013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Purine nucleoside phosphorylase is a transferase that catalyzes the addition of phosphate and removal of a purine base from guanosine and similar nucleosides. Here the interplay between sugar puckering conformation, the enzyme, and the perceived course of the reaction is examined using QM/MM FEARCF dynamics simulations. The enzyme biases the guanosine sugar ring toward a flattened (4)E conformer as a step that is critical to the success of the phosphorylation reaction. The C4' endo conformer allows the nonbonded ring oxygen orbital to align and donate electrons into the antibonding glycosidic bond orbital, thus weakening the bond. This conformational preference is due to sustained and directed noncovalent interactions anchored by the phosphate nucleophile's hydrogen bonds to the sugar C2' and C3' hydroxyls. In so doing, PNP alters the solution sugar ring pucker preferences as part of its catalytic reaction barrier lowering function.
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Affiliation(s)
- Christopher B Barnett
- Scientific Computing Research Unit and Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
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32
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Unique substrate specificity of purine nucleoside phosphorylases from Thermus thermophilus. Extremophiles 2013; 17:505-14. [DOI: 10.1007/s00792-013-0535-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 03/14/2013] [Indexed: 11/27/2022]
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Zhou X, Szeker K, Janocha B, Böhme T, Albrecht D, Mikhailopulo IA, Neubauer P. Recombinant purine nucleoside phosphorylases from thermophiles: preparation, properties and activity towards purine and pyrimidine nucleosides. FEBS J 2013; 280:1475-90. [PMID: 23332162 DOI: 10.1111/febs.12143] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2012] [Revised: 01/13/2013] [Accepted: 01/16/2013] [Indexed: 12/18/2022]
Abstract
Thermostable nucleoside phosphorylases are attractive biocatalysts for the synthesis of modified nucleosides. Hence we report on the recombinant expression of three 'high molecular mass' purine nucleoside phosphorylases (PNPs) derived from the thermophilic bacteria Deinococcus geothermalis, Geobacillus thermoglucosidasius and from the hyperthermophilic archaeon Aeropyrum pernix (5'-methythioadenosine phosphorylase; ApMTAP). Thermostability studies, kinetic analysis and substrate specificities are reported. The PNPs were stable at their optimal temperatures (DgPNP, 55 °C; GtPNP, 70 °C; ApMTAP, activity rising to 99 °C). Substrate properties were investigated for natural purine nucleosides [adenosine, inosine and their C2'-deoxy counterparts (activity within 50-500 U·mg(-1))], analogues with 2'-amino modified 2'-deoxy-adenosine and -inosine (within 0.1-3 U·mg(-1)) as well as 2'-deoxy-2'-fluoroadenosine (9) and its C2'-arabino diastereomer (10, within 0.01-0.03 U·mg(-1)). Our results reveal that the structure of the heterocyclic base (e.g. adenine or hypoxanthine) can play a critical role in the phosphorolysis reaction. The implications of this finding may be helpful for reaction mechanism studies or optimization of reaction conditions. Unexpectedly, the diastereomeric 2'-deoxyfluoro adenine ribo- and arabino-nucleosides displayed similar substrate properties. Moreover, cytidine and 2'-deoxycytidine were found to be moderate substrates of the prepared PNPs, with substrate activities in a range similar to those determined for 2'-deoxyfluoro adenine nucleosides 9 and 10. C2'-modified nucleosides are accepted as substrates by all recombinant enzymes studied, making these enzymes promising biocatalysts for the synthesis of modified nucleosides. Indeed, the prepared PNPs performed well in preliminary transglycosylation reactions resulting in the synthesis of 2'-deoxyfluoro adenine ribo- and arabino- nucleosides in moderate yield (24%).
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Affiliation(s)
- Xinrui Zhou
- Laboratory of Bioprocess Engineering, Department of Biotechnology, Technische Universität Berlin, Berlin, Germany
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Dessanti P, Zhang Y, Allegrini S, Tozzi MG, Sgarrella F, Ealick SE. Structural basis of the substrate specificity of Bacillus cereus adenosine phosphorylase. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2012; 68:239-48. [PMID: 22349225 PMCID: PMC3282621 DOI: 10.1107/s090744491200073x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2011] [Accepted: 01/07/2012] [Indexed: 11/10/2022]
Abstract
Purine nucleoside phosphorylases catalyze the phosphorolytic cleavage of the glycosidic bond of purine (2'-deoxy)nucleosides, generating the corresponding free base and (2'-deoxy)-ribose 1-phosphate. Two classes of PNPs have been identified: homotrimers specific for 6-oxopurines and homohexamers that accept both 6-oxopurines and 6-aminopurines. Bacillus cereus adenosine phosphorylase (AdoP) is a hexameric PNP; however, it is highly specific for 6-aminopurines. To investigate the structural basis for the unique substrate specificity of AdoP, the active-site mutant D204N was prepared and kinetically characterized and the structures of the wild-type protein and the D204N mutant complexed with adenosine and sulfate or with inosine and sulfate were determined at high resolution (1.2-1.4 Å). AdoP interacts directly with the preferred substrate through a hydrogen-bond donation from the catalytically important residue Asp204 to N7 of the purine base. Comparison with Escherichia coli PNP revealed a more optimal orientation of Asp204 towards N7 of adenosine and a more closed active site. When inosine is bound, two water molecules are interposed between Asp204 and the N7 and O6 atoms of the nucleoside, thus allowing the enzyme to find alternative but less efficient ways to stabilize the transition state. The mutation of Asp204 to asparagine led to a significant decrease in catalytic efficiency for adenosine without affecting the efficiency of inosine cleavage.
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Affiliation(s)
- Paola Dessanti
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853-1301, USA
- Dipartimento di Scienze del Farmaco, Università di Sassari, Italy
| | - Yang Zhang
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853-1301, USA
| | - Simone Allegrini
- Dipartimento di Scienze del Farmaco, Università di Sassari, Italy
| | | | | | - Steven E. Ealick
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853-1301, USA
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Hassan AEA, Abou-Elkhair RAI, Riordan JM, Allan PW, Parker WB, Khare R, Waud WR, Montgomery JA, Secrist JA. Synthesis and evaluation of the substrate activity of C-6 substituted purine ribosides with E. coli purine nucleoside phosphorylase: palladium mediated cross-coupling of organozinc halides with 6-chloropurine nucleosides. Eur J Med Chem 2011; 47:167-74. [PMID: 22112758 DOI: 10.1016/j.ejmech.2011.10.039] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2011] [Revised: 10/14/2011] [Accepted: 10/19/2011] [Indexed: 11/19/2022]
Abstract
A series of C-6 alkyl, cycloalkyl, and aryl-9-(β-d-ribofuranosyl)purines were synthesized and their substrate activities with Escherichia coli purine nucleoside phosphorylase (E. coli PNP) were evaluated. (Ph(3)P)(4)Pd-mediated cross-coupling reactions of 6-chloro-9-(2,3,5-tri-O-acetyl-β-d-ribofuranosyl)-purine (6) with primary alkyl (Me, Et, n-Pr, n-Bu, isoBu) zinc halides followed by treatment with NH(3)/MeOH gave the corresponding 6-alkyl-9-(β-d-ribofuranosyl)purine derivatives 7-11, respectively, in good yields. Reactions of 6 with cycloalkyl(propyl, butyl, pentyl)zinc halides and aryl (phenyl, 2-thienyl)zinc halides gave under similar conditions the corresponding 6-cyclopropyl, cyclobutyl, cyclopentyl, phenyl, and thienyl -9-(β-d-ribofuranosyl)purine derivatives 12-16, respectively in high yields. E. coli PNP showed a high tolerance to the steric and hydrophobic environment at the 6-position of the synthesized purine ribonucleosides. Significant cytotoxic activity was observed for 8, 12, 15, and 16. Evaluation of 12 and 16 against human tumor xenografts in mice did not demonstrate any selective antitumor activity. In addition, 6-methyl-9-(β-d-arabinofuranosyl)purine (18) was prepared and evaluated.
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Affiliation(s)
- Abdalla E A Hassan
- Drug Discovery Division, Southern Research Institute, P.O. Box 55305, Birmingham, AL 35255-5305, USA
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Cacciapuoti G, Marabotti A, Fuccio F, Porcelli M. Unraveling the structural and functional differences between purine nucleoside phosphorylase and 5′-deoxy-5′-methylthioadenosine phosphorylase from the archaeon Pyrococcus furiosus. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2011; 1814:1358-66. [DOI: 10.1016/j.bbapap.2011.06.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 05/17/2011] [Accepted: 06/01/2011] [Indexed: 10/18/2022]
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37
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Tran TH, Christoffersen S, Allan PW, Parker WB, Piskur J, Serra I, Terreni M, Ealick SE. The crystal structure of Streptococcus pyogenes uridine phosphorylase reveals a distinct subfamily of nucleoside phosphorylases. Biochemistry 2011; 50:6549-58. [PMID: 21707079 DOI: 10.1021/bi200707z] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Uridine phosphorylase (UP), a key enzyme in the pyrimidine salvage pathway, catalyzes the reversible phosphorolysis of uridine or 2'-deoxyuridine to uracil and ribose 1-phosphate or 2'-deoxyribose 1-phosphate. This enzyme belongs to the nucleoside phosphorylase I superfamily whose members show diverse specificity for nucleoside substrates. Phylogenetic analysis shows Streptococcus pyogenes uridine phosphorylase (SpUP) is found in a distinct branch of the pyrimidine subfamily of nucleoside phosphorylases. To further characterize SpUP, we determined the crystal structure in complex with the products, ribose 1-phosphate and uracil, at 1.8 Å resolution. Like Escherichia coli UP (EcUP), the biological unit of SpUP is a hexamer with an α/β monomeric fold. A novel feature of the active site is the presence of His169, which structurally aligns with Arg168 of the EcUP structure. A second active site residue, Lys162, is not present in previously determined UP structures and interacts with O2 of uracil. Biochemical studies of wild-type SpUP showed that its substrate specificity is similar to that of EcUP, while EcUP is ∼7-fold more efficient than SpUP. Biochemical studies of SpUP mutants showed that mutations of His169 reduced activity, while mutation of Lys162 abolished all activity, suggesting that the negative charge in the transition state resides mostly on uracil O2. This is in contrast to EcUP for which transition state stabilization occurs mostly at O4.
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Affiliation(s)
- Timothy H Tran
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853-1301, United States
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38
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Shim EJ, Przybylski JL, Wetmore SD. Effects of nucleophile, oxidative damage, and nucleobase orientation on the glycosidic bond cleavage in deoxyguanosine. J Phys Chem B 2010; 114:2319-26. [PMID: 20095611 DOI: 10.1021/jp9113656] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Deglycosylation of nucleotides occurs during many essential biological processes, including DNA repair, and is initiated by a variety of nucleophiles. In the present work, density functional theory (B3LYP) was used to investigate the thermodynamics and kinetics of the glycosidic bond cleavage reaction in the model nucleoside forms of guanine and its major oxidation product, 8-oxoguanine. Base excision facilitated by four different nucleophiles (hydroxyl anion (fully activated water), formate-water complex (partially activated water), lysine, and proline) was considered, which spans nucleophiles involved in a collection of spontaneous and enzyme-catalyzed processes. Because some enzymes that catalyze deglycosylation can accommodate more than one orientation of the base with respect to the sugar moiety, the effects of the (anti/syn) base orientation on the barrier height were also considered. We find that the nucleophile has a very large effect on the overall (gas-phase) reaction energetics. Although this effect decreases in different (polar) environments, the nucleophile has the greatest influence on the overall reaction as compared to whether the base is damaged or to the base orientation. Furthermore, the effects are significant in environments that most closely resemble (nonpolar) enzymatic active sites. Our results provide a greater understanding of the relative effects of the nucleophile, damage to the nucleobase, and the nucleobase orientation with respect to the sugar moiety on the deglycosylation pathway, which provide qualitative explanations for relative base excision rates observed in some biological systems.
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Affiliation(s)
- Eun Jung Shim
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive, Lethbridge, Alberta T1K 3M4, Canada
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39
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Przybylski JL, Wetmore SD. Modeling the dissociative hydrolysis of the natural DNA nucleosides. J Phys Chem B 2010; 114:1104-13. [PMID: 20039632 DOI: 10.1021/jp9098717] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Two-dimensional PCM-B3LYP/6-31+G(d) potential energy surfaces for the hydrolysis of the four natural 2'-deoxyribonucleosides (2'-deoxyadenosine, 2'-deoxyguanosine, 2'-deoxycytidine, and thymidine) are characterized using a model that includes both implicit (bulk) solvent effects and (three or four) explicit water molecules in the optimization routine. For the first time, the experimentally predicted dissociative (S(N)1) mechanism is found to be favored over the synchronous (S(N)2) pathway for all nucleosides studied. Due to the success of our model in stabilizing the charge-separated intermediates along the S(N)1 pathway, it is proposed that the new model presented here is the smallest system capable of generating the experimentally predicted oxacarbenium cation intermediate. We therefore stress that dissociative mechanisms should be studied with methodologies that account for the (bulk) environment in the optimization routine, where these effects are often only included as a correction to the energy in the current literature. In addition to accounting for charge stabilization through implicit solvation, nucleophile activation and leaving group stabilization should also be explicitly introduced into the model to further stabilize the system. Our work also emphasizes the importance of studying the Gibbs surface, which in some cases provides a better description of chemically important regions of the reaction surface or changes the calculated trend in the magnitude of dissociative barriers. In addition, it is proposed that the methodology presented in this study can be used to calculate uncatalyzed deglycosylation barriers for a range of DNA nucleosides, which when compared to the corresponding enzyme-catalyzed reactions, will allow the prediction of the rate enhancement (barrier reduction) due to the enzyme.
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Affiliation(s)
- Jennifer L Przybylski
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive, Lethbridge, Alberta T1K 3M4, Canada
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Kang YN, Zhang Y, Allan PW, Parker WB, Ting JW, Chang CY, Ealick SE. Structure of grouper iridovirus purine nucleoside phosphorylase. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2010; 66:155-62. [PMID: 20124695 DOI: 10.1107/s0907444909048276] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Accepted: 11/13/2009] [Indexed: 11/10/2022]
Abstract
Purine nucleoside phosphorylase (PNP) catalyzes the reversible phosphorolysis of purine ribonucleosides to the corresponding free bases and ribose 1-phosphate. The crystal structure of grouper iridovirus PNP (givPNP), corresponding to the first PNP gene to be found in a virus, was determined at 2.4 A resolution. The crystals belonged to space group R3, with unit-cell parameters a = 193.0, c = 105.6 A, and contained four protomers per asymmetric unit. The overall structure of givPNP shows high similarity to mammalian PNPs, having an alpha/beta structure with a nine-stranded mixed beta-barrel flanked by a total of nine alpha-helices. The predicted phosphate-binding and ribose-binding sites are occupied by a phosphate ion and a Tris molecule, respectively. The geometrical arrangement and hydrogen-bonding patterns of the phosphate-binding site are similar to those found in the human and bovine PNP structures. The enzymatic activity assay of givPNP on various substrates revealed that givPNP can only accept 6-oxopurine nucleosides as substrates, which is also suggested by its amino-acid composition and active-site architecture. All these results suggest that givPNP is a homologue of mammalian PNPs in terms of amino-acid sequence, molecular mass, substrate specificity and overall structure, as well as in the composition of the active site.
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Affiliation(s)
- You-Na Kang
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853-1301, USA
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41
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Afshar S, Sawaya MR, Morrison SL. Structure of a mutant human purine nucleoside phosphorylase with the prodrug, 2-fluoro-2'-deoxyadenosine and the cytotoxic drug, 2-fluoroadenine. Protein Sci 2009; 18:1107-14. [PMID: 19388075 DOI: 10.1002/pro.91] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A double mutant of human purine nucleoside phosphorylase (hDM) with the amino acid mutations Glu201Gln:Asn243Asp cleaves adenosine-based prodrugs to their corresponding cytotoxic drugs. When fused to an anti-tumor targeting component, hDM is targeted to tumor cells, where it effectively catalyzes phosphorolysis of the prodrug, 2-fluoro-2'-deoxyadenosine (F-dAdo) to the cytotoxic drug, 2-fluoroadenine (F-Ade). This cytotoxicity should be restricted only to the tumor microenvironment, because the endogenously expressed wild type enzyme cannot use adenosine-based prodrugs as substrates. To gain insight into the interaction of hDM with F-dAdo, we have determined the crystal structures of hDM with F-dAdo and F-Ade. The structures reveal that despite the two mutations, the overall fold of hDM is nearly identical to the wild type enzyme. Importantly, the residues Gln201 and Asp243 introduced by the mutation form hydrogen bond contacts with F-dAdo that result in its binding and catalysis. Comparison of substrate and product complexes suggest that the side chains of Gln201 and Asp243 as well as the purine base rotate during catalysis possibly facilitating cleavage of the glycosidic bond. The two structures suggest why hDM, unlike the wild-type enzyme, can utilize F-dAdo as substrate. More importantly, they provide a critical foundation for further optimization of cleavage of adenosine-based prodrugs, such as F-dAdo by mutants of human purine nucleoside phosphorylase.
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Affiliation(s)
- Sepideh Afshar
- Department of Microbiology, Immunology, and Molecular Genetics, UCLA-DOE Institute for Genomics and Proteomics, UCLA, Los Angeles, California 90095
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42
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Chaikuad A, Brady RL. Conservation of structure and activity in Plasmodium purine nucleoside phosphorylases. BMC STRUCTURAL BIOLOGY 2009; 9:42. [PMID: 19575810 PMCID: PMC2721837 DOI: 10.1186/1472-6807-9-42] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/26/2009] [Accepted: 07/03/2009] [Indexed: 11/10/2022]
Abstract
BACKGROUND Purine nucleoside phosphorylase (PNP) is central to purine salvage mechanisms in Plasmodium parasites, the causative agents of malaria. Most human malaria results from infection either by Plasmodium falciparum (Pf), the deadliest form of the parasite, or by the widespread Plasmodium vivax (Pv). Whereas the PNP enzyme from Pf has previously been studied in detail, despite the prevalence of Pv little is known about many of the key metabolic enzymes from this parasite, including PvPNP. RESULTS The crystal structure of PvPNP is described and is seen to have many features in common with the previously reported structure of PfPNP. In particular, the composition and conformations of the active site regions are virtually identical. The crystal structure of a complex of PfPNP co-crystallised with inosine and arsenate is also described, and is found to contain a mixture of products and reactants - hypoxanthine, ribose and arsenate. The ribose C1' in this hybrid complex lies close to the expected point of symmetry along the PNP reaction coordinate, consistent with a conformation between the transition and product states. These two Plasmodium PNP structures confirm the similarity of structure and mechanism of these enzymes, which are also confirmed in enzyme kinetic assays using an array of substrates. These reveal an unusual form of substrate activation by 2'-deoxyinosine of PvPNP, but not PfPNP. CONCLUSION The close similarity of the Pf and Pv PNP structures allows characteristic features to be identified that differentiate the Apicomplexa PNPs from the human host enzyme. This similarity also suggests there should be a high level of cross-reactivity for compounds designed to inhibit either of these molecular targets. However, despite these similarities, there are also small differences in the activities of the two Plasmodium enzymes.
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Affiliation(s)
- Apirat Chaikuad
- Department of Biochemistry, University of Bristol, Bristol, BS8 1TD, UK.
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43
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Millen AL, Wetmore SD. Glycosidic bond cleavage in deoxynucleotides — A density functional study. CAN J CHEM 2009. [DOI: 10.1139/v09-024] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Density functional theory was used to study the glycosidic bond cleavage in deoxynucleotides with the main goal to determine the effects of the nucleobase, hydrogen bonding with the nucleobase, and the (bulk) environment on the reaction energetics. Since direct glycosidic bond cleavage is a high-energy process, two nucleophile models were considered (HCOO–···H2O and HO–), which represent different stages of activation of a water nucleophile. The glycosidic bond cleavage barriers were found to decrease, while the reaction exothermicity increases, with an increase in the nucleobase acidity. The gas-phase barriers and reaction energies for bond cleavage in all deoxynucleotides were found to be significantly affected by hydrogen-bonding interactions with the nucleobase (by up to 30 kJ mol–1 depending on the nucleophile). Although the barriers increase and reaction energies become less exothermic in enzymatic and aqueous environments, the effects of the bulk environment are similar in the presence and absence of small molecules bound to the nucleobase. Therefore, the effects of hydrogen bonding with the bases are approximately the same in all environments. Our results suggest that hydrogen bonding with the nucleobase may play an important role in the glycosidic bond cleavage in both pyrimidine and purine nucleotides in a variety of environments.
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Affiliation(s)
- Andrea L. Millen
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada
| | - Stacey D. Wetmore
- Department of Chemistry and Biochemistry, University of Lethbridge, 4401 University Drive, Lethbridge, AB T1K 3M4, Canada
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Ducati RG, Santos DS, Basso LA. Substrate specificity and kinetic mechanism of purine nucleoside phosphorylase from Mycobacterium tuberculosis. Arch Biochem Biophys 2009; 486:155-64. [DOI: 10.1016/j.abb.2009.04.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Revised: 04/23/2009] [Accepted: 04/29/2009] [Indexed: 10/20/2022]
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45
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Aparoy P, Reddy RN, Guruprasad L, Reddy MR, Reddanna P. Homology modeling of 5-lipoxygenase and hints for better inhibitor design. J Comput Aided Mol Des 2008; 22:611-9. [PMID: 18231862 DOI: 10.1007/s10822-008-9180-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2007] [Accepted: 01/10/2008] [Indexed: 01/21/2023]
Abstract
Lipoxygenases (LOXs) are a group of enzymes involved in the oxygenation of polyunsaturated fatty acids. Among these 5-lipoxygenase (5-LOX) is the key enzyme leading to the formation of pharmacologically important leukotrienes and lipoxins, the mediators of inflammatory and allergic disorders. In view of close functional similarity to mammalian lipoxygenase, potato 5-LOX is used extensively. In this study, the homology modeling technique has been used to construct the structure of potato 5-LOX. The amino acid sequence identity between the target protein and sequence of template protein 1NO3 (soybean LOX-3) searched from NCBI protein BLAST was 63%. Based on the template structure, the protein model was constructed by using the Homology program in InsightII. The protein model was briefly refined by energy minimization steps and validated using Profile-3D, ERRAT and PROCHECK. The results showed that 99.3% of the amino acids were in allowed regions of Ramachandran plot, suggesting that the model is accurate and its stereochemical quality good. Like all LOXs, 5-LOX also has a two-domain structure, the small N-terminal beta-barrel domain and a larger catalytic domain containing a single atom of non-heme iron coordinating with His525, His530, His716 and Ile864. Asn720 is present in the fifth coordination position of iron. The sixth coordination position faces the open cavity occupied here by the ligands which are docked. Our model of the enzyme is further validated by examining the interactions of earlier reported inhibitors and by energy minimization studies which were carried out using molecular mechanics calculations. Four ligands, nordihydroguaiaretic acid (NDGA) having IC(50) of 1.5 microM and analogs of benzyl propargyl ethers having IC(50) values of 760 microM, 45 microM, and no inhibition respectively were selected for our docking and energy minimization studies. Our results correlated well with the experimental data reported earlier, which proved the quality of the model. This model generated can be further used for the design and development of more potent 5-LOX inhibitors.
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Affiliation(s)
- P Aparoy
- School of Life Sciences, University of Hyderabad, Hyderabad, 500 046, India
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46
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Fernández-Lucas J, Condezo LA, Quezada MA, Sinisterra JV. Low-temperature synthesis of 2'-deoxyadenosine using immobilized psychrotrophic microorganisms. Biotechnol Bioeng 2008; 100:213-22. [PMID: 18098315 DOI: 10.1002/bit.21756] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Selective biocatalyzed synthesis of 2'-deoxyadenosine from 2'-deoxypyrimidine nucleosides was carried out using free or immobilized whole cells. The reaction was performed at 57 degrees C without secondary reactions. Two psychrotrophic microorganisms, Bacillus psychrosaccharolyticus and Psychrobacter immobilis, are described for the first time as active and specific strains for the synthesis of 2'-deoxyadenosine. Adenosine deaminase activity was not detected. Whole cells were immobilized in different matrixes. Calcium alginate and calcium pectate gave the best biocatalysts. The synthesis of 2'-deoxyadenosine follows an apparent first order kinetic expression. External mass transfer control was negligible as deduced from k(s), N(A), and Omega values. Internal mass transfer was the rate controlling step according to eta(T) and phi values.
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Affiliation(s)
- J Fernández-Lucas
- Biotransformations Group, Department of Organic & Pharmaceutical Chemistry, Faculty of Pharmacy, Universidad Complutense, 28040 Madrid, Spain
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47
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Stepniak K, Zinić B, Wierzchowski J, Bzowska A. Fluorescence studies of calf spleen purine nucleoside phosphorylase (PNP) complexes with guanine and 9-deazaguanine. NUCLEOSIDES NUCLEOTIDES & NUCLEIC ACIDS 2008; 26:841-7. [PMID: 18066911 DOI: 10.1080/15257770701503985] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Interactions of trimeric calf spleen purine nucleoside phosphorylase (PNP) with guanine (Gua) and its analogue, 9-deazaguanine (9-deaza-Gua), were studied by means of the steady-state fluorescence. The aim was to test the hypothesis that the enzyme stabilizes the anionic form of purine, inferred previously from the unusual increase of fluorescence observed after binding of guanine by calf spleen PNP. We have found that the dissociation constants obtained form titration experiments are in fact pH-independent in the range 7.0-10.25 for both PNP/Gua and PNP/9-deaza-Gua complexes. In particular, at pH 7.0 we found Kd = 0.12 +/- 0.02 micro M for Gua and 0.16 +/- 0.01 micro M for 9-deaza-Gua, while at the conditions where there is more than 40% of the anionic form the respective values were Kd = 0.15 +/- 0.01 micro M for Gua (pH 9.0) and 0.25 +/- 0.02 micro M for 9-deaza-Gua (pH 10.25). Hence, the enzyme does not prefer binding of anionic forms of these ligands in respect to the neutral ones. This result questions the involvement of the anionic forms in the reaction catalyzed by trimeric PNPs, and contradicts the hypothesis of a strong hydrogen bond formation between the enzyme Asn 243 residue and the purine N7 position.
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Affiliation(s)
- Katarzyna Stepniak
- Department of Biophysics, Institute of Experimental Physics, Warsaw University, Warsaw, Poland
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Remote mutations and active site dynamics correlate with catalytic properties of purine nucleoside phosphorylase. Biophys J 2008; 94:4078-88. [PMID: 18234834 DOI: 10.1529/biophysj.107.121913] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
It has been found that with mutation of two surface residues (Lys(22) --> Glu and His(104) --> Arg) in human purine nucleoside phosphorylase (hPNP), there is an enhancement of catalytic activity in the chemical step. This is true although the mutations are quite remote from the active site, and there are no significant changes in crystallographic structure between the wild-type and mutant active sites. We propose that dynamic coupling from the remote residues to the catalytic site may play a role in catalysis, and it is this alteration in dynamics that causes an increase in the chemical step rate. Computational results indicate that the mutant exhibits stronger coupling between promotion of vibrations and the reaction coordinate than that found in native hPNP. Power spectra comparing native and mutant proteins show a correlation between the vibrations of Immucillin-G (ImmG):O5'...ImmG:N4' and H257:Ndelta...ImmG:O5' consistent with a coupling of these motions. These modes are linked to the protein promoting vibrations. Stronger coupling of motions to the reaction coordinate increases the probability of reaching the transition state and thus lowers the activation free energy. This motion has been shown to contribute to catalysis. Coincident with the approach to the transition state, the sum of the distances of ImmG:O4'...ImmG:O5'...H257:Ndelta became smaller, stabilizing the oxacarbenium ion formed at the transition state. Combined results from crystallography, mutational analysis, chemical kinetics, and computational analysis are consistent with dynamic compression playing a significant role in forming the transition state. Stronger coupling of these pairs is observed in the catalytically enhanced mutant enzyme. That motion and catalysis are enhanced by mutations remote from the catalytic site implicates dynamic coupling through the protein architecture as a component of catalysis in hPNP.
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Modrak-Wójcik A, Kirilenko A, Shugar D, Kierdaszuk B. Role of ionization of the phosphate cosubstrate on phosphorolysis by purine nucleoside phosphorylase (PNP) of bacterial (E. coli) and mammalian (human) origin. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2007; 37:153-64. [PMID: 17639373 DOI: 10.1007/s00249-007-0205-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2007] [Revised: 05/31/2007] [Accepted: 06/12/2007] [Indexed: 10/23/2022]
Abstract
Kinetics of the reactions of purine nucleoside phosphorylases (PNP) from E. coli (PNP-I, the product of the deoD gene) and human erythrocytes with their natural substrates guanosine (Guo), inosine (Ino), a substrate analogue N(7)-methylguanosine (m(7)Guo), and orthophosphate (P(i), natural cosubstrate) and its thiophosphate analogue (SP(i)), found to be a weak cosubstrate, have been studied in the pH range 5-8. In this pH range Guo and Ino exist predominantly in the neutral forms (pK(a) 9.2 and 8.8); m(7)Guo consists of an equilibrium mixture of the cationic and zwitterionic forms (pK(a) 7.0); and P(i) and SP(i) exhibit equilibria between monoanionic and dianionic forms (pK(a) 6.7 and 5.4, respectively). The phosphorolysis of m(7)Guo (at saturated concentration) with both enzymes exhibits Michaelis kinetics with SP(i), independently of pH. With P(i), the human enzyme shows Michaelis kinetics only at pH approximately 5. However, in the pH range 5-8 for the bacterial enzyme, and 6-8 for the human enzyme, enzyme kinetics with P(i) are best described by a model with high- and low-affinity states of the enzymes, denoted as enzyme-substrate complexes with one or two active sites occupied by P(i), characterized by two sets of enzyme-substrate dissociation constants (apparent Michaelis constants, K (m1) and K (m2)) and apparent maximal velocities (V (max1) and V (max2)). Their values, obtained from non-linear least-squares fittings of the Adair equation, were typical for negative cooperativity of both substrate binding (K (m1) < K (m2)) and enzyme kinetics (V (max1)/K (m1) > V (max2)/K (m2)). Comparison of the pH-dependence of the substrate properties of P(i) versus SP(i) points to both monoanionic and dianionic forms of P(i) as substrates, with a marked preference for the dianionic species in the pH range 5-8, where the population of the P(i) dianion varies from 2 to 95%, reflected by enzyme efficiency three orders of magnitude higher at pH 8 than that at pH 5. This is accompanied by an increase in negative cooperativity, characterized by a decrease in the Hill coefficient from n (H) approximately 1 to n (H) approximately 0.7 for Guo with the human enzyme, and to n (H) approximately 0.7 and 0.5 for m(7)Guo with the E. coli and human enzymes, respectively. Possible mechanisms of cooperativity are proposed. Attention is drawn to the substrate properties of SP(i) in relation to its structure.
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Affiliation(s)
- Anna Modrak-Wójcik
- Department of Biophysics, Institute of Experimental Physics, University of Warsaw, Warsaw, Poland
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Wielgus-Kutrowska B, Antosiewicz JM, Długosz M, Holý A, Bzowska A. Towards the mechanism of trimeric purine nucleoside phosphorylases: Stopped-flow studies of binding of multisubstrate analogue inhibitor — 2-amino-9-[2-(phosphonomethoxy)ethyl]-6-sulfanylpurine. Biophys Chem 2007; 125:260-8. [PMID: 16989940 DOI: 10.1016/j.bpc.2006.08.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2006] [Revised: 08/18/2006] [Accepted: 08/21/2006] [Indexed: 10/24/2022]
Abstract
The binding of multisubstrate analogue inhibitor - 2-amino-9-[2-(phosphonomethoxy)ethyl]-6-sulfanylpurine (PME-6-thio-Gua) to purine nucleoside phosphorylase from Cellulomonas sp. at 20 degrees C, in 20 mM Hepes buffer with ionic strength adjusted to 50 mM using KCl, at several pH values between 6.5 and 8.2, was investigated using a stopped-flow spectrofluorimeter. The kinetic transients registered after mixing a protein solution with ligand solutions of different concentrations were simultaneously fitted by several association reaction models using nonlinear least-squares procedure based on numerical integration of the chemical kinetic equations appropriate for given model. It is concluded that binding of a PME-6-thio-Gua molecule by each of the binding sites is sufficiently well described by one-step process, with a model assuming interacting binding sites being more probable than a model assuming independent sites. The association rate constants derived from experimental data, assuming one step binding and independent sites, are decreasing with an increase in pH, changing from 30 to 6 microM(-1)s(-1) per binding site. The dissociation rate constants are in the range of 1-3 s(-1), and they are rather insensitive of changes in pH. Interestingly, for each pH value, the one-step binding model with interacting sites results in the association rate constant per site 1.5-4 times smaller for the binding of the first ligand molecule than that for the binding of the second one. Decrease of association constants with pH indicate that the enzyme does not prefer binding of the naturally occurring anionic form of the 6-thioguanine ring (pK(a) 8.7) resulting from a dissociation of N(1)-H. This finding supports the mechanism in which hydrogen bond interaction of N(1)-H with Glu204 (Glu 201 in mammalian PNPs) is crucial in the catalytic process. Results obtained also indicate that, in contrast to transition-state analogues, for which binding is followed by a conformational change, binding of multisubstrate analogue inhibitors to trimeric PNPs is a one-step process.
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