1
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Scheerer D, Levy D, Casier R, Riven I, Mazal H, Haran G. Enzyme activation by urea reveals the interplay between conformational dynamics and substrate binding: a single-molecule FRET study. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.09.01.610662. [PMID: 39257823 PMCID: PMC11384010 DOI: 10.1101/2024.09.01.610662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/12/2024]
Abstract
Proteins often harness extensive motions of domains and subunits to promote their function. Deciphering how these movements impact activity is key for understanding life's molecular machinery. The enzyme adenylate kinase is an intriguing example for this relationship; it ensures efficient catalysis by large-scale domain motions that lead to the enclosure of the bound substrates ATP and AMP. At high concentrations, AMP also operates as an allosteric inhibitor of the protein. Surprisingly, the enzyme is activated by urea, a compound commonly acting as a denaturant. Combining single-molecule FRET spectroscopy and enzymatic activity studies, we find that urea interferes with two key mechanisms that contribute to enzyme efficacy. First, urea promotes the open conformation of the enzyme, aiding the proper positioning of the substrates. Second, urea decreases AMP affinity, paradoxically facilitating a more efficient progression towards the catalytically active complex. These results signify the important interplay between conformational dynamics and chemical steps, including binding, in the activity of enzymes. State-of-the-art tools, such as single-molecule fluorescence spectroscopy, offer new insights into how enzymes balance different conformations to regulate activity.
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Affiliation(s)
- David Scheerer
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 761001, Israel
| | - Dorit Levy
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 761001, Israel
| | - Remi Casier
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 761001, Israel
| | - Inbal Riven
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 761001, Israel
| | - Hisham Mazal
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 761001, Israel
- Max Planck Institute for the Science of Light, Erlangen 91058, Germany
| | - Gilad Haran
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 761001, Israel
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2
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Scheerer D, Adkar BV, Bhattacharyya S, Levy D, Iljina M, Riven I, Dym O, Haran G, Shakhnovich EI. Allosteric communication between ligand binding domains modulates substrate inhibition in adenylate kinase. Proc Natl Acad Sci U S A 2023; 120:e2219855120. [PMID: 37094144 PMCID: PMC10160949 DOI: 10.1073/pnas.2219855120] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 03/22/2023] [Indexed: 04/26/2023] Open
Abstract
Enzymes play a vital role in life processes; they control chemical reactions and allow functional cycles to be synchronized. Many enzymes harness large-scale motions of their domains to achieve tremendous catalytic prowess and high selectivity for specific substrates. One outstanding example is provided by the three-domain enzyme adenylate kinase (AK), which catalyzes phosphotransfer between ATP to AMP. Here we study the phenomenon of substrate inhibition by AMP and its correlation with domain motions. Using single-molecule FRET spectroscopy, we show that AMP does not block access to the ATP binding site, neither by competitive binding to the ATP cognate site nor by directly closing the LID domain. Instead, inhibitory concentrations of AMP lead to a faster and more cooperative domain closure by ATP, leading in turn to an increased population of the closed state. The effect of AMP binding can be modulated through mutations throughout the structure of the enzyme, as shown by the screening of an extensive AK mutant library. The mutation of multiple conserved residues reduces substrate inhibition, suggesting that substrate inhibition is an evolutionary well conserved feature in AK. Combining these insights, we developed a model that explains the complex activity of AK, particularly substrate inhibition, based on the experimentally observed opening and closing rates. Notably, the model indicates that the catalytic power is affected by the microsecond balance between the open and closed states of the enzyme. Our findings highlight the crucial role of protein motions in enzymatic activity.
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Affiliation(s)
- David Scheerer
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 761001, Israel
| | - Bharat V Adkar
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138
| | | | - Dorit Levy
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 761001, Israel
| | - Marija Iljina
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 761001, Israel
| | - Inbal Riven
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 761001, Israel
| | - Orly Dym
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 761001, Israel
| | - Gilad Haran
- Department of Chemical and Biological Physics, Weizmann Institute of Science, Rehovot 761001, Israel
| | - Eugene I Shakhnovich
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138
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3
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Zhang Y, Chen M, Lu J, Li W, Wolynes PG, Wang W. Frustration and the Kinetic Repartitioning Mechanism of Substrate Inhibition in Enzyme Catalysis. J Phys Chem B 2022; 126:6792-6801. [PMID: 36044985 PMCID: PMC9483917 DOI: 10.1021/acs.jpcb.2c03832] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
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Substrate inhibition, whereby enzymatic activity decreases
with
excess substrate after reaching a maximum turnover rate, is among
the most elusive phenomena in enzymatic catalysis. Here, based on
a dynamic energy landscape model, we investigate the underlying mechanism
by performing molecular simulations and frustration analysis for a
model enzyme adenylate kinase (AdK), which catalyzes the phosphoryl
transfer reaction ATP + AMP ⇋ ADP + ADP. Intriguingly, these
reveal a kinetic repartitioning mechanism of substrate inhibition,
whereby excess substrate AMP suppresses the population of an energetically
frustrated, but kinetically activated, catalytic pathway going through
a substrate (ATP)-product (ADP) cobound complex with steric incompatibility.
Such a frustrated pathway plays a crucial role in facilitating the
bottleneck product ADP release, and its suppression by excess substrate
AMP leads to a slow down of product release and overall turnover.
The simulation results directly demonstrate that substrate inhibition
arises from the rate-limiting product-release step, instead of the
steps for populating the catalytically competent complex as often
suggested in previous works. Furthermore, there is a tight interplay
between the enzyme conformational equilibrium and the extent of substrate
inhibition. Mutations biasing to more closed conformations tend to
enhance substrate inhibition. We also characterized the key features
of single-molecule enzyme kinetics with substrate inhibition effect.
We propose that the above molecular mechanism of substrate inhibition
may be relevant to other multisubstrate enzymes in which product release
is the bottleneck step.
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Affiliation(s)
- Yangyang Zhang
- Department of Physics, National Laboratory of Solid State Microstructure, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.,Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, Zhejiang 325000, China
| | - Mingchen Chen
- Department of Research and Development, neoX Biotech, Beijing 102206, China.,Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, United States
| | - Jiajun Lu
- Department of Physics, National Laboratory of Solid State Microstructure, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
| | - Wenfei Li
- Department of Physics, National Laboratory of Solid State Microstructure, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China.,Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou, Zhejiang 325000, China
| | - Peter G Wolynes
- Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, United States
| | - Wei Wang
- Department of Physics, National Laboratory of Solid State Microstructure, and Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, China
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4
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Finger Y, Habich M, Gerlich S, Urbanczyk S, van de Logt E, Koch J, Schu L, Lapacz KJ, Ali M, Petrungaro C, Salscheider SL, Pichlo C, Baumann U, Mielenz D, Dengjel J, Brachvogel B, Hofmann K, Riemer J. Proteasomal degradation induced by DPP9-mediated processing competes with mitochondrial protein import. EMBO J 2020; 39:e103889. [PMID: 32815200 PMCID: PMC7527813 DOI: 10.15252/embj.2019103889] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Revised: 06/29/2020] [Accepted: 07/03/2020] [Indexed: 12/14/2022] Open
Abstract
Plasticity of the proteome is critical to adapt to varying conditions. Control of mitochondrial protein import contributes to this plasticity. Here, we identified a pathway that regulates mitochondrial protein import by regulated N-terminal processing. We demonstrate that dipeptidyl peptidases 8/9 (DPP8/9) mediate the N-terminal processing of adenylate kinase 2 (AK2) en route to mitochondria. We show that AK2 is a substrate of the mitochondrial disulfide relay, thus lacking an N-terminal mitochondrial targeting sequence and undergoing comparatively slow import. DPP9-mediated processing of AK2 induces its rapid proteasomal degradation and prevents cytosolic accumulation of enzymatically active AK2. Besides AK2, we identify more than 100 mitochondrial proteins with putative DPP8/9 recognition sites and demonstrate that DPP8/9 influence the cellular levels of a number of these proteins. Collectively, we provide in this study a conceptual framework on how regulated cytosolic processing controls levels of mitochondrial proteins as well as their dual localization to mitochondria and other compartments.
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Affiliation(s)
- Yannik Finger
- Institute of Biochemistry, Redox Biochemistry, University of Cologne, Cologne, Germany
| | - Markus Habich
- Institute of Biochemistry, Redox Biochemistry, University of Cologne, Cologne, Germany
| | - Sarah Gerlich
- Institute of Biochemistry, Redox Biochemistry, University of Cologne, Cologne, Germany
| | - Sophia Urbanczyk
- Division of Molecular Immunology, Department of Internal Medicine III, Nikolaus-Fiebiger-Center, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Erik van de Logt
- Institute of Biochemistry, Redox Biochemistry, University of Cologne, Cologne, Germany
| | - Julian Koch
- Institute of Biochemistry, Redox Biochemistry, University of Cologne, Cologne, Germany
| | - Laura Schu
- Institute of Biochemistry, Redox Biochemistry, University of Cologne, Cologne, Germany
| | - Kim Jasmin Lapacz
- Institute of Biochemistry, Redox Biochemistry, University of Cologne, Cologne, Germany
| | - Muna Ali
- Institute of Biochemistry, Redox Biochemistry, University of Cologne, Cologne, Germany
| | - Carmelina Petrungaro
- Institute of Biochemistry, Redox Biochemistry, University of Cologne, Cologne, Germany
| | | | - Christian Pichlo
- Institute of Biochemistry, University of Cologne, Cologne, Germany
| | - Ulrich Baumann
- Institute of Biochemistry, University of Cologne, Cologne, Germany
| | - Dirk Mielenz
- Division of Molecular Immunology, Department of Internal Medicine III, Nikolaus-Fiebiger-Center, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Joern Dengjel
- Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Bent Brachvogel
- Department of Pediatrics and Adolescent Medicine, Experimental Neonatology, Faculty of Medicine, University of Cologne, Cologne, Germany.,Center for Biochemistry, Faculty of Medicine, University of Cologne, Cologne, Germany
| | - Kay Hofmann
- Institute of Genetics, University of Cologne, Cologne, Germany
| | - Jan Riemer
- Institute of Biochemistry, Redox Biochemistry, University of Cologne, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), University of Cologne, Cologne, Germany
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5
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Substrate inhibition imposes fitness penalty at high protein stability. Proc Natl Acad Sci U S A 2019; 116:11265-11274. [PMID: 31097595 DOI: 10.1073/pnas.1821447116] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Proteins are only moderately stable. It has long been debated whether this narrow range of stabilities is solely a result of neutral drift toward lower stability or purifying selection against excess stability-for which no experimental evidence was found so far-is also at work. Here, we show that mutations outside the active site in the essential Escherichia coli enzyme adenylate kinase (Adk) result in a stability-dependent increase in substrate inhibition by AMP, thereby impairing overall enzyme activity at high stability. Such inhibition caused substantial fitness defects not only in the presence of excess substrate but also under physiological conditions. In the latter case, substrate inhibition caused differential accumulation of AMP in the stationary phase for the inhibition-prone mutants. Furthermore, we show that changes in flux through Adk could accurately describe the variation in fitness effects. Taken together, these data suggest that selection against substrate inhibition and hence excess stability may be an important factor determining stability observed for modern-day Adk.
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6
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Expression of adenylate kinase fused MEK1R4F in Escherichia coli and its application in ERK phosphorylation. Biotechnol Lett 2017; 39:1553-1558. [PMID: 28748350 DOI: 10.1007/s10529-017-2385-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Accepted: 06/22/2017] [Indexed: 01/29/2023]
Abstract
OBJECTIVE To construct a highly expressed and active MEK1R4F (a constitutively active form of mitogen-activated protein kinase kinase 1) by fusion of soluble adenylate kinase (Adk) tag, resulting in Adk-MEK1R4F protein suitable for preparation of phosphorylated ERK. RESULTS We fused the Adk to the N-terminus of MEK1R4F through overlapping PCR. The expression of Adk-MEK1R4F fusion protein increased ~10-fold in Escherichia coli, and was purified to 95% via two purification steps including Ni-NTA and Q Sepharose fast flow (QFF) chromatography. The purified Adk-MEK1R4F protein was functional for ERK phosphorylation and could use ADP in addition to ATP. The Adk-MEK1R4F had higher catalytic activity than regular MEK1R4F both in vitro and in cell-free extracts system. CONCLUSIONS Adenylate kinase was used as a soluble tag to facilitate MEK1R4F protein expression and its application in large-scale phosphorylated ERK1/2 preparation and purification.
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7
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Gutmann A, Nidetzky B. Unlocking the Potential of Leloir Glycosyltransferases for Applied Biocatalysis: Efficient Synthesis of Uridine 5′-Diphosphate-Glucose by Sucrose Synthase. Adv Synth Catal 2016. [DOI: 10.1002/adsc.201600754] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Alexander Gutmann
- Institute of Biotechnology and Biochemical Engineering; Graz University of Technology, NAWI Graz; Petersgasse 12 8010 Graz Austria
| | - Bernd Nidetzky
- Institute of Biotechnology and Biochemical Engineering; Graz University of Technology, NAWI Graz; Petersgasse 12 8010 Graz Austria
- Austrian Centre of Industrial Biotechnology; Petersgasse 14 8010 Graz Austria
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8
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Luo D, Wen C, Zhao R, Liu X, Liu X, Cui J, Liang JG, Liang P. High Level Expression and Purification of Recombinant Proteins from Escherichia coli with AK-TAG. PLoS One 2016; 11:e0156106. [PMID: 27214237 PMCID: PMC4877045 DOI: 10.1371/journal.pone.0156106] [Citation(s) in RCA: 7] [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: 02/02/2016] [Accepted: 05/08/2016] [Indexed: 01/01/2023] Open
Abstract
Adenylate kinase (AK) from Escherichia coli was used as both solubility and affinity tag for recombinant protein production. When fused to the N-terminus of a target protein, an AK fusion protein could be expressed in soluble form and purified to near homogeneity in a single step from Blue-Sepherose via affinity elution with micromolar concentration of P1, P5- di (adenosine—5’) pentaphosphate (Ap5A), a transition-state substrate analog of AK. Unlike any other affinity tags, the level of a recombinant protein expression in soluble form and its yield of recovery during each purification step could be readily assessed by AK enzyme activity in near real time. Coupled to a His-Tag installed at the N-terminus and a thrombin cleavage site at the C terminus of AK, the streamlined method, here we dubbed AK-TAG, could also allow convenient expression and retrieval of a cleaved recombinant protein in high yield and purity via dual affinity purification steps. Thus AK-TAG is a new addition to the arsenal of existing affinity tags for recombinant protein expression and purification, and is particularly useful where soluble expression and high degree of purification are at stake.
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Affiliation(s)
- Dan Luo
- Department of Biochemistry & Molecular Biology, School of Life Sciences, Sichuan University, Chengdu, China
| | - Caixia Wen
- Department of Biochemistry & Molecular Biology, School of Life Sciences, Sichuan University, Chengdu, China
| | - Rongchuan Zhao
- Department of Biochemistry & Molecular Biology, School of Life Sciences, Sichuan University, Chengdu, China
| | - Xinyu Liu
- Department of Biochemistry & Molecular Biology, School of Life Sciences, Sichuan University, Chengdu, China
| | - Xinxin Liu
- Department of Biochemistry & Molecular Biology, School of Life Sciences, Sichuan University, Chengdu, China
| | - Jingjing Cui
- Department of Biochemistry & Molecular Biology, School of Life Sciences, Sichuan University, Chengdu, China
| | | | - Peng Liang
- Department of Biochemistry & Molecular Biology, School of Life Sciences, Sichuan University, Chengdu, China
- Clover Biopharmaceuticals, Chengdu, China
- GenHunter Corporation, Grassmere Park, Nashville, United States of America
- * E-mail: ;
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9
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Use of adenylate kinase as a solubility tag for high level expression of T4 DNA ligase in Escherichia coli. Protein Expr Purif 2015; 109:79-84. [PMID: 25700573 DOI: 10.1016/j.pep.2015.02.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2015] [Revised: 02/09/2015] [Accepted: 02/10/2015] [Indexed: 11/20/2022]
Abstract
The discovery of T4 DNA ligase in 1960s was pivotal in the spread of molecular biotechnology. The enzyme has become ubiquitous for recombinant DNA routinely practiced in biomedical research around the globe. Great efforts have been made to express and purify T4 DNA ligase to meet the world demand, yet over-expression of soluble T4 DNA ligase in E. coli has been difficult. Here we explore the use of adenylate kinase to enhance T4 DNA ligase expression and its downstream purification. E.coli adenylate kinase, which can be expressed in active form at high level, was fused to the N-terminus of T4 DNA ligase. The resulting His-tagged AK-T4 DNA ligase fusion protein was greatly over-expressed in E. coli, and readily purified to near homogeneity via two purification steps consisting of Blue Sepharose and Ni-NTA chromatography. The purified AK-T4 DNA ligase not only is fully active for DNA ligation, but also can use ADP in addition to ATP as energy source since adenylate kinase converts ADP to ATP and AMP. Thus adenylate kinase may be used as a solubility tag to facilitate recombinant protein expression as well as their downstream purification.
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10
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Ravilious GE, Westfall CS, Jez JM. Redox-linked gating of nucleotide binding by the N-terminal domain of adenosine 5'-phosphosulfate kinase. J Biol Chem 2013; 288:6107-15. [PMID: 23322773 DOI: 10.1074/jbc.m112.439414] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Adenosine 5'-phosphosulfate kinase (APSK) catalyzes the phosphorylation of adenosine 5'-phosphosulfate (APS) to 3'-phosphoadenosine-5'-phosphosulfate (PAPS). Crystallographic studies of APSK from Arabidopsis thaliana revealed the presence of a regulatory intersubunit disulfide bond (Cys(86)-Cys(119)). The reduced enzyme displayed improved catalytic efficiency and decreased effectiveness of substrate inhibition by APS compared with the oxidized form. Here we examine the effect of disulfide formation and the role of the N-terminal domain on nucleotide binding using isothermal titration calorimetry (ITC) and steady-state kinetics. Formation of the disulfide bond in A. thaliana APSK (AtAPSK) inverts the binding affinities at the ATP/ADP and APS/PAPS sites from those observed in the reduced enzyme, consistent with initial binding of APS as inhibitory, and suggests a role for the N-terminal domain in guiding nucleotide binding order. To test this, an N-terminal truncation variant (AtAPSKΔ96) was generated. The resulting protein was completely insensitive to substrate inhibition by APS. ITC analysis of AtAPSKΔ96 showed decreased affinity for APS binding, although the N-terminal domain does not directly interact with this ligand. Moreover, AtAPSKΔ96 displayed reduced affinity for ADP, which corresponds to a loss of substrate inhibition by formation of an E·ADP·APS dead end complex. Examination of the AtAPSK crystal structure suggested Arg(93) as important for positioning of the N-terminal domain. ITC and kinetic analysis of the R93A mutant also showed a complete loss of substrate inhibition and altered nucleotide binding affinities, which mimics the effect of the N-terminal deletion. These results show how thiol-linked changes in AtAPSK alter the energetics of binding equilibria to control its activity.
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11
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Tan YW, Hanson JA, Yang H. Direct Mg(2+) binding activates adenylate kinase from Escherichia coli. J Biol Chem 2009; 284:3306-3313. [PMID: 19029291 PMCID: PMC3837426 DOI: 10.1074/jbc.m803658200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2008] [Revised: 11/07/2008] [Indexed: 01/23/2023] Open
Abstract
We report evidence that adenylate kinase (AK) from Escherichia coli can be activated by the direct binding of a magnesium ion to the enzyme, in addition to ATP-complexed Mg(2+). By systematically varying the concentrations of AMP, ATP, and magnesium in kinetic experiments, we found that the apparent substrate inhibition of AK, formerly attributed to AMP, was suppressed at low magnesium concentrations and enhanced at high magnesium concentrations. This previously unreported magnesium dependence can be accounted for by a modified random bi-bi model in which Mg(2+) can bind to AK directly prior to AMP binding. A new kinetic model is proposed to replace the conventional random bi-bi mechanism with substrate inhibition and is able to describe the kinetic data over a physiologically relevant range of magnesium concentrations. According to this model, the magnesium-activated AK exhibits a 23- +/- 3-fold increase in its forward reaction rate compared with the unactivated form. The findings imply that Mg(2+) could be an important affecter in the energy signaling network in cells.
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Affiliation(s)
- Yan-Wen Tan
- Department of Chemistry, University of California at Berkeley, Berkeley, California 94720
| | - Jeffrey A Hanson
- Department of Chemistry, University of California at Berkeley, Berkeley, California 94720
| | - Haw Yang
- Department of Chemistry, University of California at Berkeley, Berkeley, California 94720; Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720.
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12
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Spuergin P, Abele U, Schulz GE. Stability, Activity and Structure of Adenylate Kinase Mutants. ACTA ACUST UNITED AC 2008. [DOI: 10.1111/j.1432-1033.1995.0405e.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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13
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Hibino T. Nonfixed relationship of the Michaelis constant and maximum velocity with their corresponding rate constants. J Biol Chem 2005; 280:30671-80. [PMID: 15972825 DOI: 10.1074/jbc.m412601200] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Michaelis constant (K(m)) and V(mas) (E0k(cat)) values for two mutant sets of enzymes were studied from the viewpoint of their definition in a rapid equilibrium reaction model and in a steady state reaction model. The "AMP set enzyme" had a mutation at the AMP-binding site (Y95F, V67I, and V67I/L76V), and the "ATP set enzyme" had a mutation at a possible ATP-binding region (Y32F, Y34F, and Y32A/Y34A). Reaction rate constants obtained using steady state model analysis explained discrepancies found by the rapid equilibrium model analysis. (i) The unchanged number of bound AMPs for Y95F and the wild type despite the markedly increased K(m) values for AMP of the AMP set of enzymes was explained by alteration of the rate constants of the AMP step (k(+2), k(-2)) to retain the ratio k(+2)/k(-2). (ii) A 100 times weakened selectivity of ATP for Y34F in contrast to no marked changes in K(m) values for both ATP and AMP for the ATP set of enzymes was explained by the alteration of the rate constants of the ATP steps. A similar alteration of the K(m) and k(cat) values of these enzymes resulted from distinctive alterations of their rate constants. The pattern of alteration was highly suggestive. The most interesting finding was that the rate constants that decided the K(m) and k(cat) values were replaced by the mutation, and the simple relationships between K(m), k(cat), and the rate constants of K(m)1 = k(+1)/k(-1) and k(cat) = k(f) were not valid. The nature of the K(m) and k(cat) alterations was discussed.
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Affiliation(s)
- Takeshi Hibino
- Laboratory of Biophysical Chemistry, Graduate School of Agriculture and Biological Sciences, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan
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14
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Iwai T, Kuramitsu S, Masui R. The Nudix hydrolase Ndx1 from Thermus thermophilus HB8 is a diadenosine hexaphosphate hydrolase with a novel activity. J Biol Chem 2004; 279:21732-9. [PMID: 15024014 DOI: 10.1074/jbc.m312018200] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The ndx1 gene, which encodes a Nudix protein, was cloned from the extremely thermophilic bacterium Thermus thermophilus HB8. This gene encodes a 126-amino acid protein that includes the characteristic Nudix motif conserved among Nudix proteins. Ndx1 was overexpressed in Escherichia coli and purified. Ndx1 was stable up to 95 degrees C and at extreme pH. Size exclusion chromatography indicated that Ndx1 was monomeric in solution. Ndx1 specifically hydrolyzed (di)adenosine polyphosphates but not ATP or diadenosine triphosphate, and it always generated ATP as the product. Diadenosine hexaphosphate (Ap(6)A), the most preferred substrate, was hydrolyzed to produce two ATP molecules, which is a novel hydrolysis mode for Ap(6)A, with a K(m) of 1.4 microm and a k(cat) of 4.1 s(-1). These results indicate that Ndx1 is a (di)adenosine polyphosphate hydrolase. Ndx1 activity required the presence of the divalent cations Mn(2+), Mg(2+), Zn(2+), and Co(2+), whereas Ca(2+), Ni(2+), and Cu(2+) were not able to activate Ndx1. Fluoride ion inhibited Ndx1 activity via a non-competitive mechanism. Optimal activity for Ap(6)A was observed at around pH 8.0 and about 70 degrees C. We found two important residues with pK(a) values of 6.1 and 9.6 in the free enzyme and pK(a) values of 7.9 and 10.0 in the substrate-enzyme complex. Kinetic studies of proteins with amino acid substitutions suggested that Glu-46 and Glu-50 were conserved residues in the Nudix motif and were involved in catalysis. Trp-26 was likely involved in enzyme-substrate interactions based on fluorescence measurements. Based on these results, the mechanism of substrate recognition and catalysis are discussed.
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Affiliation(s)
- Takayoshi Iwai
- Department of Biology, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043
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15
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Yamada M, Sugahara M, Hishitani Y, Nobumoto M, Nakazawa A. Isolation and characterization of mutated mitochondrial GTP:AMP phosphotransferase. J Mol Biol 1998; 280:551-8. [PMID: 9665856 DOI: 10.1006/jmbi.1998.1876] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
GTP:AMP phosphotransferase (adenylate kinase isozyme 3, AK3) mutants were obtained by using the ability of AK3 to complement a temperature-sensitive mutation of Escherichia coli adenylate kinase (AKe). Five mutants, P16L, G19S, G91D, G91S, and P93L, had mutation sites located at two loops that are involved in substrate binding of the enzyme. P16L and G19S bearing changes at the first loop showed reduced affinity for both GTP and AMP, the extent of reduction being slightly higher for GTP than AMP. In contrast, G91S and P93L having alterations at the second loop had lower affinities for AMP. Only the alterations at the second loop strongly influenced the Vmax value of the enzyme. Another mutant, D163N, had a substitution at the site forming a salt bridge in adenylate kinase isozyme 1 (AK1), which influenced the Vmax as well as the Km values for both substrates. The kinetic characteristics of these mutants were comparable to those of the corresponding AK1 or AKe mutants. Furthermore, from the results of mutations T201P and T201A that had alterations in all the kinetic parameters of AK3 and from a comparison with the structure and the kinetic parameters of AKe, we expect that a residue(s) around Thr201 is involved in recognition of the base of nucleoside triphosphate.
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Affiliation(s)
- M Yamada
- Department of Biological Chemistry, Faculty of Agriculture, Yamaguchi University, Yamaguchi, 753-8515, Japan
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16
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Sinev MA, Sineva EV, Ittah V, Haas E. Towards a mechanism of AMP-substrate inhibition in adenylate kinase from Escherichia coli. FEBS Lett 1996; 397:273-6. [PMID: 8955362 DOI: 10.1016/s0014-5793(96)01195-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Crystallographic studies on adenylate kinase (AK) suggest that binding of ATP causes the LID domain of the enzyme to close over the ATP molecule (Schlauderer et al. (1996) J. Mol. Biol. 256, 223-227). The method of time-resolved fluorescence resonance energy transfer was applied to study the proposed structural change in AK from Escherichia coli. Two active derivatives of the (C77S, A73C, V142C)-AK mutant containing the excitation energy donor attached to one of the two cysteine residues and the acceptor attached to the other cysteine were prepared to monitor displacements of the LID domain in response to substrate binding. Binding of either ATP or AMP was accompanied by an approximately 9 A decrease in the interprobe distances suggesting LID domain closure. Closure of the LID domain in response to AMP binding may be a possible reason for the strong AMP-substrate inhibition known for E. coli AK.
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Affiliation(s)
- M A Sinev
- Department of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
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17
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Li Y, Zhang Y, Yan H. Kinetic and thermodynamic characterizations of yeast guanylate kinase. J Biol Chem 1996; 271:28038-44. [PMID: 8910414 DOI: 10.1074/jbc.271.45.28038] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Yeast guanylate kinase was expressed at high level in Escherichia coli using pET-17b vector. It was purified to homogeneity by a simple two-column procedure with an average yield of approximately 100 mg/liter. The steady-state kinetic parameters for both forward and reverse reactions were determined by initial velocity measurements. The turnover numbers (kcat) were 394 s-1 for the forward reaction (formation of ADP and GDP) and 90 s-1 for the reverse reaction (formation of ATP and GMP). Km values were 0.20, 0. 091, 0.017, and 0.097 mM for MgATP, GMP, MgADP, and GDP, respectively. Analysis of the initial velocity patterns indicated a sequential mechanism. GMP was found to have partial substrate inhibition. The substrate inhibition was not competitive with MgATP and could be attributed to formation of the abortive complex guanylate kinase.MgADP.GMP. The equilibrium constant of the reaction was measured under various conditions by NMR and a radiometric assay. The results showed that the steady-state kinetic parameters were consistent with the thermodynamic constant. NMR titration and equilibrium dialysis showed that both substrates and products could bind to free guanylate kinase. The dissociation constants were 0.090, 0.18, 0.029, 0.084, and 0.12 mM for MgATP, ATP, GMP, MgADP, and GDP, respectively. Viscosity-dependent kinetics was used to identify the rate-limiting steps of the reaction. The results indicated that the reaction rate is largely controlled by the chemical step.
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Affiliation(s)
- Y Li
- Department of Biochemistry, Michigan State University, East Lansing, Michigan 48824, USA
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18
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Abstract
The method of time-resolved dynamic nonradiative excitation energy transfer (ET) was used to analyze the proposed domain closure in adenylate kinase (AK). A highly active mutant of Escherichia coli AK, (C77S, V169W, A55C)-AK, was prepared, in which the solvent- accessible residues valine 169 and alanine 55 were replaced by tryptophan (the donor of excitation energy) and cysteine, respectively. The latter was subsequently labeled with either 5- or 4-acetamidosalicylic acid (the acceptor). From the comparative analysis of AK crystal structures [Schulz, G.E., Müller, C.W., & Diederichs, K. (1990) J. Mol. Biol. 213, 627-630] (apo-AK,AK.AMP complex and AK.AP5A [P1,P5-di(adenosine-5') pentaphosphate] complex), "sequential formation" of the pseudoternary AK.AP5A complex is followed by two- step domain closure. The domain closure reduces interdomain distances in a two-step manner. Specifically, the distance between C alpha-atoms of the residues 169 and 55 (numbers correspond to those of E. coli AK) is decreased from 23.6 A in the apo-enzyme to 16.2 A upon the formation of the AK.AMP complex and to 12.3 A upon the further formation of the pseudoternary AK.AP5A complex. Time-resolved dynamic nonradiative excitation energy transfer was measured for the following ligand forms of the labeled derivative of the mutant enzyme: the apo-enzyme, the enzyme-MgATP complex, the enzyme.AMP complex, and the enzyme.AP5A "ternary" complex. The transfer efficiencies, which were determined in these experiments, were approximately 7.5%, 22%, 33%, and 65%, respectively. Global analyses of the time resolved ET experiments with the same ligand forms yielded intermolecular distance distributions with corresponding means of 31, 23, 19, and 12 A and full widths at half- maximum of 29, 24, 14, and 11 A. The data confirmed the proposed stepwise manner of the domain closure of the enzyme and revealed the presence of multiple conformations of E. coli AK in solution.
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Affiliation(s)
- M A Sinev
- Department of Life Sciences, Bar-Ilan University, Ramat Gan, Israel
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19
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Bilderback T, Fulmer T, Mantulin WW, Glaser M. Substrate binding causes movement in the ATP binding domain of Escherichia coli adenylate kinase. Biochemistry 1996; 35:6100-6. [PMID: 8634252 DOI: 10.1021/bi951833i] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Crystallographic evidence suggests that there is a large hinged domain motion associated with substrate binding in adenylate kinase. To test this hypothesis, resonance energy transfer measurements of substrate binding were initiated. Adenylate kinase from Escherichia coli consists of three domains: the main body of the enzyme with alpha-helical and beta-sheet secondary structure, and domains that close over the AMP and ATP binding sites. Four single tryptophan mutants were constructed to map distances. Two tryptophan mutants were positioned at residues 133 (Y133W) and 137 (F137W), which are in the domain that closes over the ATP binding site. Mutant F86W that is located at the AMP binding site, and mutant S41W that is in the loop that close over AMP, complete the mapping library. Energy transfer was measured between each of these tryptophans and 5-[[2-(acetylamino)ethyl]amino]naphthalene-1-sulfonic acid (AEDANS) covalently bound to the single cysteine residue at position 77, which is located in the main body of adenylate kinase. The distance between the tryptophan of the F137W mutant adenylate kinase and the AEDANS-labeled Cys-77 decreased by 12.1 A upon the binding of the bisubstrate inhibitor P1, P5-bis(5'-adenosyl) pentaphosphate (AP5A). There were only small alterations in the tryptophan to Cys-77-AEDANS distances in the Y133W, F86W, and S41W mutants upon the binding of AP5A, ATP, or AMP, implying that movement of residues 133, 86, and 41 in relation to the Cys-77 residue was minimal. These results suggest that there is significant closure of the ATP binding domain upon the binding of ATP or AP5A. Unexpectedly, exposure of the enzyme to AMP also introduced a partial closure of the ATP hinged domain.
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Affiliation(s)
- T Bilderback
- Department of Biochemistry, University of Illinois, Urbana 61801, USA
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20
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Zhao Z, Liu X, Shi Z, Danley L, Huang B, Jiang RT, Tsai MD. Mechanism of Adenylate Kinase. 20. Probing the Importance of the Aromaticity in Tyrosine-95 and the Ring Size in Proline-17 with Unnatural Amino Acids. J Am Chem Soc 1996. [DOI: 10.1021/ja9600901] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Zhong Zhao
- Departments of Chemistry and Biochemistry and Ohio State Biochemistry Program The Ohio State University, Columbus, Ohio 43210 Department of Chemistry, University of California at Berkley, Berkley, California 94720
| | - Xiaohong Liu
- Departments of Chemistry and Biochemistry and Ohio State Biochemistry Program The Ohio State University, Columbus, Ohio 43210 Department of Chemistry, University of California at Berkley, Berkley, California 94720
| | - Zhengtao Shi
- Departments of Chemistry and Biochemistry and Ohio State Biochemistry Program The Ohio State University, Columbus, Ohio 43210 Department of Chemistry, University of California at Berkley, Berkley, California 94720
| | - Lora Danley
- Departments of Chemistry and Biochemistry and Ohio State Biochemistry Program The Ohio State University, Columbus, Ohio 43210 Department of Chemistry, University of California at Berkley, Berkley, California 94720
| | - Baohua Huang
- Departments of Chemistry and Biochemistry and Ohio State Biochemistry Program The Ohio State University, Columbus, Ohio 43210 Department of Chemistry, University of California at Berkley, Berkley, California 94720
| | - Ru-Tai Jiang
- Departments of Chemistry and Biochemistry and Ohio State Biochemistry Program The Ohio State University, Columbus, Ohio 43210 Department of Chemistry, University of California at Berkley, Berkley, California 94720
| | - Ming-Daw Tsai
- Departments of Chemistry and Biochemistry and Ohio State Biochemistry Program The Ohio State University, Columbus, Ohio 43210 Department of Chemistry, University of California at Berkley, Berkley, California 94720
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21
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Spuergin P, Abele U, Schulz GE. Stability, activity and structure of adenylate kinase mutants. EUROPEAN JOURNAL OF BIOCHEMISTRY 1995; 231:405-13. [PMID: 7635152 DOI: 10.1111/j.1432-1033.1995.tb20713.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Sequence/structure relationships have been explored by site-directed mutagenesis using a structurally known adenylate kinase. In particular the effects of helix capping and nonpolar core expansion on thermodynamic stability have been analyzed. Six point mutations were produced and characterized by SDS/PAGE, native PAGE, isoelectric focussing, electrophoretic titration, enzyme kinetics, and X-ray structure analysis. Heat-denaturation experiments yielded melting temperatures Tm and melting enthalpy changes delta Hm. The heat capacity change delta Cp of the wild-type enzyme was determined by guanidine hydrochloride denaturation in conjunction with Tm and delta Hm. Using the wild-type delta Cp value, Gibbs free energy changes delta G at room temperature were calculated for all mutants. Four mutants were designed for helix capping stabilization, but only one of them showed such an effect. Because of electrostatic interference with the induced-fit motion, one mutant decreased the catalytic activity strongly. Two mutants expanded nonpolar cores causing destabilization. The mutant with the lower stability could be crystallized and subjected to an X-ray analysis at 223-pm resolution which showed the structural changes. The enzyme was stabilized by adding a -Pro-His-His tail to the C-terminal alpha-helix for nickel-chelate chromatography. This addition constitutes a helix cap. Taken together, the results demonstrate that stabilization by helix capping is difficult to achieve because the small positive effect is drowned by adverse mutational disruption. Further addition of atoms to nonpolar cores destabilized the protein, although the involved geometry changes were very small, demonstrating the importance of efficient packing.
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Affiliation(s)
- P Spuergin
- Institut für Organische Chemie und Biochemie, Albert-Ludwigs-Universität, Freiburg im Breisgau, Germany
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22
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Kern P, Rognan D, Folkers G. MD simulations in Pseudo-Particle Fluids: Applications to active-site Protein Complexes. ACTA ACUST UNITED AC 1995. [DOI: 10.1002/qsar.19950140302] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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23
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Kern P, Brunne RM, Folkers G. Nucleotide-binding properties of adenylate kinase from Escherichia coli: a molecular dynamics study in aqueous and vacuum environments. J Comput Aided Mol Des 1994; 8:367-88. [PMID: 7815090 DOI: 10.1007/bf00125373] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The complex of adenylate kinase with its transition-state inhibitor has been studied by molecular dynamics simulations in water and in vacuum environments with the GROMOS force field over a period of 300 ps. The adenylate kinase, a member of the nucleotide-binding protein family, was exemplarily chosen for the inspection of the nucleotide-binding properties in the active site. The ligand binding and the domain movements have been studied in detail over the simulation period and compared with the crystal structure. Secondary structure transitions and domain closures defined those parts of the structure which are involved in an induced-fit movement of the enzyme. The presence of more stable hydrogen bonds on the substrate side leads to the assumption that substrate binding is more specific than cosubstrate binding. Reliable results were achieved only if water was explicitly included in the stimulation.
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Affiliation(s)
- P Kern
- Department of Pharmacy, ETH, Zürich, Switzerland
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24
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Berry MB, Meador B, Bilderback T, Liang P, Glaser M, Phillips GN. The closed conformation of a highly flexible protein: the structure of E. coli adenylate kinase with bound AMP and AMPPNP. Proteins 1994; 19:183-98. [PMID: 7937733 DOI: 10.1002/prot.340190304] [Citation(s) in RCA: 122] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The structure of E. coli adenylate kinase with bound AMP and AMPPNP at 2.0 A resolution is presented. The protein crystallizes in space group C2 with two molecules in the asymmetric unit, and has been refined to an R factor of 20.1% and an Rfree of 31.6%. In the present structure, the protein is in the closed (globular) form with the large flexible lid domain covering the AMPPNP molecule. Within the protein, AMP and AMPPNP, and ATP analog, occupy the AMP and ATP sites respectively, which had been suggested by the most recent crystal structure of E. coli adenylate kinase with Ap5A bound (Müller and Schulz, 1992, ref. 1) and prior fluorescence studies (Liang et al., 1991, ref. 2). The binding of substrates and the positions of the active site residues are compared between the present structure and the E. coli adenylate kinase/Ap5A structure. We failed to detect a peak in the density map corresponding to the Mg2+ ion which is required for catalysis, and its absence has been attributed to the use of ammonium sulfate in the crystallization solution. Finally, a comparison is made between the present structure and the structure of the heavy chain of muscle myosin.
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Affiliation(s)
- M B Berry
- W.M. Keck Center for Computational Biology, Rice University, Houston, Texas 77251-1892
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25
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Zhang YL, Zhou JM, Tsou CL. Inactivation precedes conformation change during thermal denaturation of adenylate kinase. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1164:61-7. [PMID: 8518297 DOI: 10.1016/0167-4838(93)90112-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
During the thermal denaturation of rabbit muscle adenylate kinase, the extents and rates of both unfolding and aggregation are dependent on protein concentration. Under identical conditions, inactivation takes place at a lower temperature than noticeable conformational changes and aggregation as measured by fluorescence, second derivative absorption spectroscopy, far ultraviolet circular dichroism and light scattering. Kinetics of inactivation can be resolved into two phases and at the same protein concentrations, the unfolding and aggregation rates are about one order of magnitude slower than the fast phase and approximately the same as the slow phase rate of the inactivation reaction between 35 and 60 degrees C. This is in general accord with the suggestion made previously that the active site of this enzyme is situated in a region more flexible than the molecule as a whole (Tsou, C.L. (1986) Trends Biochem. Sci. 11, 427-429). The inactivated enzyme cannot be reactivated by cooling and standing at 4 degrees C but can be over 80% reactivated by cooling and first standing in 3 M guanidine hydrochloride followed by diluting out the denaturant.
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Affiliation(s)
- Y L Zhang
- National Laboratory of Biomacromolecules, Institute of Biophysics, Academia Sinica, Beijing, China
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26
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Müller CW, Schulz GE. Structure of the complex between adenylate kinase from Escherichia coli and the inhibitor Ap5A refined at 1.9 A resolution. A model for a catalytic transition state. J Mol Biol 1992; 224:159-77. [PMID: 1548697 DOI: 10.1016/0022-2836(92)90582-5] [Citation(s) in RCA: 412] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The structure of adenylate kinase from Escherichia coli ligated with the two-substrate-mimicking inhibitor P1,P5-bis(adenosine-5'-)pentaphosphate has been determined by X-ray diffraction and refined to a resolution of 1.9 A. The asymmetric unit of the crystals contains two copies of the complex, the structures of which agree well with each other. One of these copies is less well ordered in the crystals than the other, it shows generally higher temperature factors. The molecular packing in the crystals is discussed and correlated to crystal habit and anisotropic X-ray diffraction. The bound inhibitor simulates well the binding of substrates ATP and AMP, which are clearly assigned. The alpha-phosphate of AMP is well positioned for a nucleophilic attack on the gamma-phosphate of ATP. The observed structure readily allows the construction of a stabilized pentaco-ordinated transition state, as proposed for the known in-line mechanism of the enzyme, with nucleophile and leaving group in the apical positions of a trigonal bipyramid. The kinetic data of numerous mutations reported in the literature are correlated with the detailed structure of the enzyme. The mutants were classified. The concomitant increase of the Michaelis constants for ATP and AMP in the group of mutants that modify only the ATP-binding site cannot be explained.
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Affiliation(s)
- C W Müller
- Institut für Organische Chemie und Biochemie der Universität, Freiburg, Germany
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27
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Structural and functional consequences of amino acid substitutions in the second conserved loop of Escherichia coli adenylate kinase. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54334-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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28
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Tsai MD, Yan HG. Mechanism of adenylate kinase: site-directed mutagenesis versus X-ray and NMR. Biochemistry 1991; 30:6806-18. [PMID: 2069947 DOI: 10.1021/bi00242a002] [Citation(s) in RCA: 91] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- M D Tsai
- Department of Chemistry, Ohio State University, Columbus 43210
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