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Jiang S, Lin Y, Zheng S. Development of the IMP biosensor for rapid and stable analysis of IMP concentrations in fermentation broth. Biotechnol J 2024; 19:e2400040. [PMID: 38863123 DOI: 10.1002/biot.202400040] [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: 01/17/2024] [Revised: 04/15/2024] [Accepted: 04/22/2024] [Indexed: 06/13/2024]
Abstract
IMP (inosinic acid) is a crucial intermediate in the purine metabolic pathway and is continuously synthesized in all cells. Besides its role as a precursor for DNA and RNA, IMP also plays a critical or essential role in cell growth, energy storage, conversion, and metabolism. In our study, we utilized the circularly permuted fluorescent protein (cpFP) and IMP dehydrogenase to screen and develop the IMP biosensor, IMPCP1. By introducing a mutation in the catalytically active site of IMPCP1, from Cys to Ala, we disrupted its ability to catalyze IMP while retaining its capability to bind to IMP without affecting the IMP concentration in the sample. To immobilize IMPCP1, we employed the SpyCatcher/SpyTag system and securely attached it to Magarose-Epoxy, resulting in the development of the IMP rapid test kit, referred to as IMPTK. The biosensor integrated into IMPTK offers enhanced stability, resistance to degradation activity, and specific recognition of IMP. It is also resistant to peroxides and temperature changes. IMPTK serves as a rapid and stable assay for analyzing IMP concentrations in fermentation broth. Within the linear range of IMP concentrations, it can be utilized as a substitute for HPLC. The IMPTK biosensor provides a reliable and efficient alternative for monitoring IMP levels, offering advantages such as speed, stability, and resistance to environmental factors.
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Affiliation(s)
- Shibo Jiang
- Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, P.R. China
- Guangdong Research Center of Industrial Enzyme and Green Manufacturing Technology, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, P.R. China
| | - Ying Lin
- Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, P.R. China
- Guangdong Research Center of Industrial Enzyme and Green Manufacturing Technology, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, P.R. China
| | - Suiping Zheng
- Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, P.R. China
- Guangdong Research Center of Industrial Enzyme and Green Manufacturing Technology, School of Biology and Biological Engineering, South China University of Technology, Guangzhou, P.R. China
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2
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Winkler KF, Panse L, Maiwald C, Hayeß J, Fischer P, Fehlau M, Neubauer P, Kurreck A. Screening the Thermotoga maritima genome for new wide-spectrum nucleoside and nucleotide kinases. J Biol Chem 2023:104746. [PMID: 37094698 DOI: 10.1016/j.jbc.2023.104746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 04/12/2023] [Accepted: 04/16/2023] [Indexed: 04/26/2023] Open
Abstract
Enzymes from thermophilic organisms are interesting biocatalysts for a wide variety of applications in organic synthesis, biotechnology and molecular biology. Next to an increased stability at elevated temperatures, they were described to show a wider substrate spectrum than their mesophilic counterparts. To identify thermostable biocatalysts for the synthesis of nucleotide analogs, we performed a database search on the carbohydrate and nucleotide metabolism of T. maritima. After expression and purification of 13 enzyme candidates involved in nucleotide synthesis, these enzymes were screened for their substrate scope. We found that the synthesis of 2'-deoxynucleoside 5'-monophosphates (dNMPs) and uridine 5'-monophosphate from nucleosides was catalyzed by the already known wide-spectrum thymidine kinase (TK) and the ribokinase. In contrast, no NMP-forming activity was detected for adenosine-specific kinase, uridine kinase or nucleotidase. The NMP kinases (NMPKs) and the pyruvate-phosphate-dikinase of T. maritima exhibited a rather specific substrate spectrum for the phosphorylation of NMPs, while pyruvate kinase, acetate kinase and three of the NMPKs showed a broad substrate scope with (2'-deoxy)nucleoside 5'-diphosphates as substrates. Based on these promising results, TmNMPKs were applied in enzymatic cascade reactions for nucleoside 5'-triphosphate synthesis using four modified pyrimidine nucleosides and four purine NMPs as substrates, and we determined that base- and sugar-modified substrates were accepted. In summary, besides the already reported TmTK, NMPKs of T. maritima were identified to be interesting enzyme candidates for the enzymatic production of modified nucleotides.
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Affiliation(s)
- Katja F Winkler
- Technische Universität Berlin, Faculty III Process Sciences, Institute of Biotechnology, Chair of Bioprocess Engineering, Ackerstraße 76, 13355 Berlin, Germany
| | - Lena Panse
- Technische Universität Berlin, Faculty III Process Sciences, Institute of Biotechnology, Chair of Bioprocess Engineering, Ackerstraße 76, 13355 Berlin, Germany
| | | | - Josefine Hayeß
- Technische Universität Berlin, Faculty III Process Sciences, Institute of Biotechnology, Chair of Bioprocess Engineering, Ackerstraße 76, 13355 Berlin, Germany
| | - Pascal Fischer
- Technische Universität Berlin, Faculty III Process Sciences, Institute of Biotechnology, Chair of Bioprocess Engineering, Ackerstraße 76, 13355 Berlin, Germany
| | - Maryke Fehlau
- Technische Universität Berlin, Faculty III Process Sciences, Institute of Biotechnology, Chair of Bioprocess Engineering, Ackerstraße 76, 13355 Berlin, Germany; BioNukleo GmbH, Ackerstraße 76, 13355 Berlin, Germany
| | - Peter Neubauer
- Technische Universität Berlin, Faculty III Process Sciences, Institute of Biotechnology, Chair of Bioprocess Engineering, Ackerstraße 76, 13355 Berlin, Germany
| | - Anke Kurreck
- Technische Universität Berlin, Faculty III Process Sciences, Institute of Biotechnology, Chair of Bioprocess Engineering, Ackerstraße 76, 13355 Berlin, Germany; BioNukleo GmbH, Ackerstraße 76, 13355 Berlin, Germany.
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The Power of Biocatalysts for Highly Selective and Efficient Phosphorylation Reactions. Catalysts 2022. [DOI: 10.3390/catal12111436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Reactions involving the transfer of phosphorus-containing groups are of key importance for maintaining life, from biological cells, tissues and organs to plants, animals, humans, ecosystems and the whole planet earth. The sustainable utilization of the nonrenewable element phosphorus is of key importance for a balanced phosphorus cycle. Significant advances have been achieved in highly selective and efficient biocatalytic phosphorylation reactions, fundamental and applied aspects of phosphorylation biocatalysts, novel phosphorylation biocatalysts, discovery methodologies and tools, analytical and synthetic applications, useful phosphoryl donors and systems for their regeneration, reaction engineering, product recovery and purification. Biocatalytic phosphorylation reactions with complete conversion therefore provide an excellent reaction platform for valuable analytical and synthetic applications.
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Design and construction of chimeric linker library with controllable flexibilities for precision protein engineering. Methods Enzymol 2020; 647:23-49. [PMID: 33482990 DOI: 10.1016/bs.mie.2020.12.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Linkers play essential roles in the engineering of fusion proteins, and have been extensively demonstrated to affect protein properties such as expression level, solubility, and biological functions. For linker design and optimization, one of the key factors is the flexibility or rigidity of linkers, which describes the tendency of a linker to maintain a stable conformation when expressed, and can directly contribute to the physical distance between domains of a fusion protein. In this chapter, we discuss the design and engineering of linkers in fusion proteins, and describe a library-based method for optimization of linker flexibility. This approach is based on chimeric linkers, which are composed of both flexible and rigid (helix-forming) linker motifs. We demonstrate that the chimeric linker library capable of controlling the flexibility in a wide range can fill the gap between flexible and rigid linkers by molecular dynamics simulation and fluorescence resonance energy transfer experiments, as well as its applications in fusion protein optimization.
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A study on the effects of linker flexibility on acid phosphatase PhoC-GFP fusion protein using a novel linker library. Enzyme Microb Technol 2016; 83:1-6. [DOI: 10.1016/j.enzmictec.2015.11.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 10/30/2015] [Accepted: 11/08/2015] [Indexed: 12/19/2022]
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New biocatalysts for one pot multistep enzymatic synthesis of pyrimidine nucleoside diphosphates from readily available reagents. ACTA ACUST UNITED AC 2015. [DOI: 10.1016/j.molcatb.2014.12.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Phosphoryl transfer from α-d-glucose 1-phosphate catalyzed by Escherichia coli sugar-phosphate phosphatases of two protein superfamily types. Appl Environ Microbiol 2014; 81:1559-72. [PMID: 25527541 DOI: 10.1128/aem.03314-14] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The Cori ester α-d-glucose 1-phosphate (αGlc 1-P) is a high-energy intermediate of cellular carbohydrate metabolism. Its glycosidic phosphomonoester moiety primes αGlc 1-P for flexible exploitation in glucosyl and phosphoryl transfer reactions. Two structurally and mechanistically distinct sugar-phosphate phosphatases from Escherichia coli were characterized in this study for utilization of αGlc 1-P as a phosphoryl donor substrate. The agp gene encodes a periplasmic αGlc 1-P phosphatase (Agp) belonging to the histidine acid phosphatase family. Had13 is from the haloacid dehydrogenase-like phosphatase family. Cytoplasmic expression of Agp (in E. coli Origami B) gave a functional enzyme preparation (kcat for phosphoryl transfer from αGlc 1-P to water, 40 s(-1)) that was shown by mass spectrometry to exhibit no free cysteines and the native intramolecular disulfide bond between Cys(189) and Cys(195). Enzymatic phosphoryl transfer from αGlc 1-P to water in H2 (18)O solvent proceeded with complete (18)O label incorporation into the phosphate released, consistent with catalytic reaction through O-1-P, but not C-1-O, bond cleavage. Hydrolase activity of both enzymes was not restricted to a glycosidic phosphomonoester substrate, and d-glucose 6-phosphate was converted with a kcat similar to that of αGlc 1-P. By examining phosphoryl transfer from αGlc 1-P to an acceptor substrate other than water (d-fructose or d-glucose), we discovered that Agp exhibited pronounced synthetic activity, unlike Had13, which utilized αGlc 1-P mainly for phosphoryl transfer to water. By applying d-fructose in 10-fold molar excess over αGlc 1-P (20 mM), enzymatic conversion furnished d-fructose 1-phosphate as the main product in a 55% overall yield. Agp is a promising biocatalyst for use in transphosphorylation from αGlc 1-P.
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Serra I, Conti S, Piškur J, Clausen AR, Munch-Petersen B, Terreni M, Ubiali D. ImmobilizedDrosophila melanogasterDeoxyribonucleoside Kinase (DmdNK) as a High Performing Biocatalyst for the Synthesis of Purine Arabinonucleotides. Adv Synth Catal 2014. [DOI: 10.1002/adsc.201300649] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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A comparative study on phosphotransferase activity of acid phosphatases from Raoultella planticola and Enterobacter aerogenes on nucleosides, sugars, and related compounds. Appl Microbiol Biotechnol 2013; 98:3013-22. [DOI: 10.1007/s00253-013-5194-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Accepted: 08/11/2013] [Indexed: 10/26/2022]
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Huang Z, Zhang C, Chen S, Ye F, Xing XH. Active inclusion bodies of acid phosphatase PhoC: aggregation induced by GFP fusion and activities modulated by linker flexibility. Microb Cell Fact 2013; 12:25. [PMID: 23497261 PMCID: PMC3608069 DOI: 10.1186/1475-2859-12-25] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2012] [Accepted: 03/01/2013] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Biologically active inclusion bodies (IBs) have gained much attention in recent years. Fusion with IB-inducing partner has been shown to be an efficient strategy for generating active IBs. To make full use of the advantages of active IBs, one of the key issues will be to improve the activity yield of IBs when expressed in cells, which would need more choices on IB-inducing fusion partners and approaches for engineering IBs. Green fluorescent protein (GFP) has been reported to aggregate when overexpressed, but GFP fusion has not been considered as an IB-inducing approach for these fusion proteins so far. In addition, the role of linker in fusion proteins has been shown to be important for protein characteristics, yet impact of linker on active IBs has never been reported. RESULTS Here we report that by fusing GFP and acid phosphatase PhoC via a linker region, the resultant PhoC-GFPs were expressed largely as IBs. These IBs show high levels of specific fluorescence and specific PhoC activities (phosphatase and phosphotransferase), and can account for up to over 80% of the total PhoC activities in the cells. We further demonstrated that the aggregation of GFP moiety in the fusion protein plays an essential role in the formation of PhoC-GFP IBs. In addition, PhoC-GFP IBs with linkers of different flexibility were found to exhibit different levels of activities and ratios in the cells, suggesting that the linker region can be utilized to manipulate the characteristics of active IBs. CONCLUSIONS Our results show that active IBs of PhoC can be generated by GFP fusion, demonstrating for the first time the potential of GFP fusion to induce active IB formation of another soluble protein. We also show that the linker sequence in PhoC-GFP fusion proteins plays an important role on the regulation of IB characteristics, providing an alternative and important approach for engineering of active IBs with the goal of obtaining high activity yield of IBs.
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Affiliation(s)
- Ziliang Huang
- Key Laboratory for Industrial Biocatalysis, Ministry of Education, Department of Chemical Engineering, Tsinghua University, Beijing, 100084, China
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Hurt JK, Coleman JL, Fitzpatrick BJ, Taylor-Blake B, Bridges AS, Vihko P, Zylka MJ. Prostatic acid phosphatase is required for the antinociceptive effects of thiamine and benfotiamine. PLoS One 2012; 7:e48562. [PMID: 23119057 PMCID: PMC3485352 DOI: 10.1371/journal.pone.0048562] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 09/27/2012] [Indexed: 01/19/2023] Open
Abstract
Thiamine (Vitamin B1) is an essential vitamin that must be obtained from the diet for proper neurological function. At higher doses, thiamine and benfotiamine (S-benzoylthiamine O-monophosphate, BT)–a phosphorylated derivative of thiamine–have antinociceptive effects in animals and humans, although how these compounds inhibit pain is unknown. Here, we found that Prostatic acid phosphatase (PAP, ACPP) can dephosphorylate BT in vitro, in dorsal root ganglia (DRG) neurons and in primary-afferent axon terminals in the dorsal spinal cord. The dephosphorylated product S-benzoylthiamine (S-BT) then decomposes to O-benzoylthiamine (O-BT) and to thiamine in a pH-dependent manner, independent of additional enzymes. This unique reaction mechanism reveals that BT only requires a phosphatase for conversion to thiamine. However, we found that the antinociceptive effects of BT, thiamine monophosphate (TMP) and thiamine–a compound that is not phosphorylated–were entirely dependent on PAP at the spinal level. Moreover, pharmacokinetic studies with wild-type and Pap−/− mice revealed that PAP is not required for the conversion of BT to thiamine in vivo. Taken together, our study highlights an obligatory role for PAP in the antinociceptive effects of thiamine and phosphorylated thiamine analogs, and suggests a novel phosphatase-independent function for PAP.
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Affiliation(s)
- Julie K. Hurt
- Department of Cell and Molecular Physiology, UNC Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, United States of America
| | - Jennifer L. Coleman
- Department of Cell and Molecular Physiology, UNC Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, United States of America
| | - Brendan J. Fitzpatrick
- Department of Cell and Molecular Physiology, UNC Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, United States of America
| | - Bonnie Taylor-Blake
- Department of Cell and Molecular Physiology, UNC Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, United States of America
| | - Arlene S. Bridges
- Department of Cell and Molecular Physiology, UNC Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, United States of America
| | - Pirkko Vihko
- Department of Clinical Medicine, Division of Clinical Chemistry, HUSLAB, University of Helsinki, Helsinki, Finland
| | - Mark J. Zylka
- Department of Cell and Molecular Physiology, UNC Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, United States of America
- * E-mail:
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Babich L, Hartog AF, van der Horst MA, Wever R. Continuous-flow reactor-based enzymatic synthesis of phosphorylated compounds on a large scale. Chemistry 2012; 18:6604-9. [PMID: 22505143 DOI: 10.1002/chem.201200101] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Indexed: 11/06/2022]
Abstract
Acid phosphatase, an enzyme that is able to catalyze the transfer of a phosphate group from cheap pyrophosphate to alcoholic substrates, was covalently immobilized on polymethacrylate beads with an epoxy linker (Immobeads-150 or Sepabeads EC-EP). After immobilization 70% of the activity was retained and the immobilized enzyme was stable for many months. With the immobilized enzyme we were able to produce and prepare D-glucose-6-phosphate, N-acetyl-D-glucosamine-6-phosphate, allyl phosphate, dihydroxyacetone phosphate, glycerol-1-phosphate, and inosine-5'-monophosphate from the corresponding primary alcohol on gram scale using either a fed-batch reactor or a continuous-flow packed-bed reactor.
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Affiliation(s)
- Lara Babich
- Van't Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
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Enzymatic production of 5'-inosinic acid by a newly synthesised acid phosphatase/phosphotransferase. Food Chem 2012; 134:948-56. [PMID: 23107712 DOI: 10.1016/j.foodchem.2012.02.213] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2011] [Revised: 02/13/2012] [Accepted: 02/29/2012] [Indexed: 11/20/2022]
Abstract
5'-Nucleotides including 5'-inosinic acid have characteristic taste and important application in various foods as flavour potentiators. The selective nucleoside acid phosphatase/phosphotransferase (AP/PTase) can catalyse the synthesis of 5'-nucleotides by transfer of phosphate groups. In this study, a 747-bp gene encoding AP/PTase from Escherichia blattae was synthesised. After expression, the recombinant AP/PTase was purified using nickel-NTA. The optimal temperature and pH of this enzyme were 30°C and 5.0, respectively. The activity was partially inhibited by metal ions such as Hg(2+), Ag(+) and Cu(2+), but not by chelating reagents such as EDTA. The values of K(m) and V(max) for inosine were 40 mM and 3.5 U/mg, respectively. Using this purified enzyme, 16.83 mM of 5'-IMP was synthesised from 37 mM of inosine and the molar yield reached 45.5%. Homology modelling and docking simulation were discussed.
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Psakis G, Saidijam M, Shibayama K, Polaczek J, Bettaney KE, Baldwin JM, Baldwin SA, Hope R, Essen LO, Essenberg RC, Henderson PJF. The sodium-dependent D-glucose transport protein of Helicobacter pylori. Mol Microbiol 2009; 71:391-403. [PMID: 19161491 DOI: 10.1111/j.1365-2958.2008.06535.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Helicobacter pylori is a gram-negative pathogenic microaerophile with a particular tropism for the mucosal surface of the gastric epithelium. Despite its obligatory microaerophilic character, it can metabolize D-glucose and/or D-galactose in both oxidative and fermentative pathways via a Na(+)-dependent secondary active transport, a glucokinase and enzymes of the pentose phosphate pathway. We have assigned the Na(+)-dependent transport of glucose to the protein product of the H. pylori 1174 gene. The gene was heterologously expressed in a glucose transport-deficient Escherichia coli strain, where transport activities of radiolabelled D-glucose, D-galactose and 2-deoxy-D-glucose were restored, consistent with the expected specificity of the hexose uptake system in H. pylori. D-mannose was also identified as a substrate. The HP1174 transport protein was purified and reconstituted into proteoliposomes, where sodium dependence of sugar transport activity was demonstrated. Additionally the tryptophan/tyrosine fluorescence of the purified protein showed quenching by 2-deoxy-D-glucose, D-mannose, D-glucose or D-galactose in the presence of sodium ions. This is the first reported purification and characterization of an active glucose transport protein member of the TC 2.1.7 subgroup of the Major Facilitator Superfamily, constituting the route for entry of sugar nutrients into H. pylori. A model is derived of its three-dimensional structure as a paradigm of the family.
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Affiliation(s)
- Georgios Psakis
- The Astbury Centre for Structural Molecular Biology, Institute of Membrane and Systems Biology, University of Leeds, Leeds LS2 9JT, UK
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Suzuki EI, Ishikawa K, Mihara Y, Shimba N, Asano Y. Structural-Based Engineering for Transferases to Improve the Industrial Production of 5′-Nucleotides. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2007. [DOI: 10.1246/bcsj.80.276] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Ishikawa K, Mihara Y, Shimba N, Ohtsu N, Kawasaki H, Suzuki EI, Asano Y. Enhancement of nucleoside phosphorylation activity in an acid phosphatase. Protein Eng Des Sel 2002; 15:539-43. [PMID: 12200535 DOI: 10.1093/protein/15.7.539] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Escherichia blattae non-specific acid phosphatase (EB-NSAP) possesses a pyrophosphate-nucleoside phosphotransferase activity, which is C-5'-position selective. Current mutational and structural data were used to generate a mutant EB-NSAP for a potential industrial application as an effective and economical protein catalyst in synthesizing nucleotides from nucleosides. First, Gly74 and Ile153 were replaced by Asp and Thr, respectively, since the corresponding replacements in the homologous enzyme from Morganella morganii reduced the K(m) value for inosine and thus increased the productivity of 5'-IMP. We determined the crystal structure of G74D/I153T, which has a reduced K(m) value for inosine, as expected. The tertiary structure of G74D/I153T was virtually identical to that of the wild-type. In addition, neither of the introduced side chains of Asp74 and Thr153 is directly involved in the interaction with inosine in a hypothetical binding mode of inosine to EB-NSAP, although both residues are situated near a potential inosine-binding site. These findings suggested that a slight structural change caused by an amino acid replacement around the potential inosine-binding site could significantly reduce the K(m) value. Prompted by this hypothesis, we designed several mutations and introduced them to G74D/I153T, to decrease the K(m) value further. This strategy produced a S72F/G74D/I153T mutant with a 5.4-fold lower K(m) value and a 2.7-fold higher V(max) value as compared to the wild-type EB-NSAP.
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Affiliation(s)
- Kohki Ishikawa
- Central Research Laboratories, Ajinomoto Co., Inc., 1-1 Suzuki-cho Kawasaki-ku, Kawasaki 210-868, Japan
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