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Deng H, Qin M, Liu Z, Yang Y, Wang Y, Yao L. Engineering the Active Site Lid Dynamics to Improve the Catalytic Efficiency of Yeast Cytosine Deaminase. Int J Mol Sci 2023; 24:ijms24076592. [PMID: 37047565 PMCID: PMC10095239 DOI: 10.3390/ijms24076592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 03/23/2023] [Accepted: 03/27/2023] [Indexed: 04/05/2023] Open
Abstract
Conformational dynamics is important for enzyme catalysis. However, engineering dynamics to achieve a higher catalytic efficiency is still challenging. In this work, we develop a new strategy to improve the activity of yeast cytosine deaminase (yCD) by engineering its conformational dynamics. Specifically, we increase the dynamics of the yCD C-terminal helix, an active site lid that controls the product release. The C-terminal is extended by a dynamical single α-helix (SAH), which improves the product release rate by up to ~8-fold, and the overall catalytic rate kcat by up to ~2-fold. It is also shown that the kcat increase is due to the favorable activation entropy change. The NMR H/D exchange data indicate that the conformational dynamics of the transition state analog complex increases as the helix is extended, elucidating the origin of the enhanced catalytic entropy. This study highlights a novel dynamics engineering strategy that can accelerate the overall catalysis through the entropy-driven mechanism.
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Affiliation(s)
- Hanzhong Deng
- Qingdao New Energy Shandong Laboratory, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Shandong Energy Institute, Qingdao 266101, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Mingming Qin
- Qingdao New Energy Shandong Laboratory, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Shandong Energy Institute, Qingdao 266101, China
| | - Zhijun Liu
- National Facility for Protein Science, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai 201210, China
| | - Ying Yang
- Qingdao New Energy Shandong Laboratory, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Shandong Energy Institute, Qingdao 266101, China
| | - Yefei Wang
- Qingdao New Energy Shandong Laboratory, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Shandong Energy Institute, Qingdao 266101, China
| | - Lishan Yao
- Qingdao New Energy Shandong Laboratory, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
- Shandong Energy Institute, Qingdao 266101, China
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2
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The current toolbox for APOBEC drug discovery. Trends Pharmacol Sci 2022; 43:362-377. [PMID: 35272863 PMCID: PMC9018551 DOI: 10.1016/j.tips.2022.02.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 02/03/2022] [Accepted: 02/09/2022] [Indexed: 12/14/2022]
Abstract
Mutational processes driving genome evolution and heterogeneity contribute to immune evasion and therapy resistance in viral infections and cancer. APOBEC3 (A3) enzymes promote such mutations by catalyzing the deamination of cytosines to uracils in single-stranded DNA. Chemical inhibition of A3 enzymes may yield an antimutation therapeutic strategy to improve the durability of current drug therapies that are prone to resistance mutations. A3 small-molecule drug discovery efforts to date have been restricted to a single high-throughput biochemical activity assay; however, the arsenal of discovery assays has significantly expanded in recent years. The assays used to study A3 enzymes are reviewed here with an eye towards their potential for small-molecule discovery efforts.
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3
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Sen A, Gaded V, Jayapal P, Rajaraman G, Anand R. Insights into the Dual Shuttle Catalytic Mechanism of Guanine Deaminase. J Phys Chem B 2021; 125:8814-8826. [PMID: 34324362 DOI: 10.1021/acs.jpcb.1c06127] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Guanine deaminases (GD) are essential enzymes that help in regulating the nucleobase pool. Since the deamination reaction can result in the accumulation of mutagenic bases that can lead to genomic instability, these enzymes are tightly regulated and are nonpromiscuous. Here, we delineate the basis of their substrate fidelity via entailing the reaction mechanism of deamination by employing density functional theory (DFT) calculations on NE0047, a GD from Nitrosomonas europaea. The results show that, unlike pyrimidine deaminases, which require a single glutamic acid as a proton shuttle, GDs involve two amino acids, E79 and E143 (numbering in NE0047), which control its reactivity. The hybrid quantum mechanics/molecular mechanics (QM/MM) calculations have shown that the first Zn-bound proton transfer to the N3 atom of the substrate is mediated by the E79 residue, and the second proton is transferred to the amine nitrogen of substrate via E143. Moreover, cluster models reveal that the crystallographic water molecules near the active site control the reactivity. A comparison with human GD reveals that the proposed catalytic mechanism is generic, and the knowledge generated here can be effectively applied to design selective inhibitors.
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Affiliation(s)
- Asmita Sen
- Department of Chemistry, Indian Institute of Technology-Bombay, Mumbai 400076, India
| | - Vandana Gaded
- Department of Chemistry, Indian Institute of Technology-Bombay, Mumbai 400076, India
| | - Prabha Jayapal
- Department of Chemistry, Indian Institute of Technology-Bombay, Mumbai 400076, India
| | - Gopalan Rajaraman
- Department of Chemistry, Indian Institute of Technology-Bombay, Mumbai 400076, India
| | - Ruchi Anand
- Department of Chemistry, Indian Institute of Technology-Bombay, Mumbai 400076, India
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4
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Singh J, Gaded V, Bitra A, Anand R. Structure guided mutagenesis reveals the substrate determinants of guanine deaminase. J Struct Biol 2021; 213:107747. [PMID: 34010666 DOI: 10.1016/j.jsb.2021.107747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Revised: 05/05/2021] [Accepted: 05/13/2021] [Indexed: 10/21/2022]
Abstract
Guanine deaminases (GDs) are essential enzymes that regulate the overall nucleobase pool. Since the deamination of guanine to xanthine results in the production of a mutagenic base, these enzymes have evolved to be very specific in nature. Surprisingly, they accept structurally distinct triazine ammeline, an intermediate in the melamine pathway, as one of the moonlighting substrates. Here, by employing NE0047 (a GD from Nitrosomonas europaea), we delineate the nuance in the catalytic mechanism that allows these two distinct substrates to be catalyzed. A combination of enzyme kinetics, X-ray crystallographic, and calorimetric studies reveal that GDs operate via a dual proton shuttle mechanism with two glutamates, E79 and E143, crucial for deamination. Additionally, N66 appears to be central for substrate anchoring and participates in catalysis. The study highlights the importance of closure of the catalytic loop and of maintenance of the hydrophobic core by capping residues like F141 and F48 for the creation of an apt environment for activation of the zinc-assisted catalysis. This study also analyzes evolutionarily distinct GDs and asserts that GDs incorporate subtle variations in the active site architectures while keeping the most critical active site determinants conserved.
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Affiliation(s)
- Jayanti Singh
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, Maharashtra 400076, India
| | - Vandana Gaded
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, Maharashtra 400076, India
| | - Aruna Bitra
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, Maharashtra 400076, India
| | - Ruchi Anand
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai, Maharashtra 400076, India.
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5
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Ferreira P, Cerqueira NM, Brás NF, Fernandes PA, Ramos MJ. Parametrization of Molybdenum Cofactors for the AMBER Force Field. J Chem Theory Comput 2018; 14:2538-2548. [DOI: 10.1021/acs.jctc.8b00137] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Pedro Ferreira
- UCIBIO-REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, s/n, 4169-007 Porto, Portugal
| | - Nuno M.F.S.A. Cerqueira
- UCIBIO-REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, s/n, 4169-007 Porto, Portugal
| | - Natércia F. Brás
- UCIBIO-REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, s/n, 4169-007 Porto, Portugal
| | - Pedro A. Fernandes
- UCIBIO-REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, s/n, 4169-007 Porto, Portugal
| | - Maria J. Ramos
- UCIBIO-REQUIMTE, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, s/n, 4169-007 Porto, Portugal
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6
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Sethi S, Takashima Y, Nakamura S, Fujimoto K. Effect of substitution of photo-cross-linker in photochemical cytosine to uracil transition in DNA. Bioorg Med Chem Lett 2017; 27:3905-3908. [DOI: 10.1016/j.bmcl.2017.06.042] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Revised: 06/14/2017] [Accepted: 06/14/2017] [Indexed: 11/25/2022]
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7
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Sethi S, Ooe M, Sakamoto T, Fujimoto K. Effect of nucleobase change on cytosine deamination through DNA photo-cross-linking reaction via 3-cyanovinylcarbazole nucleoside. MOLECULAR BIOSYSTEMS 2017; 13:1152-1156. [PMID: 28453010 DOI: 10.1039/c7mb00082k] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Photo-chemical deamination of cytosine using 3-cyanovinylcarbazole nucleoside (CNVK) mediated photo-cross-linking is a technique for site-directed mutagenesis. Using this technique in vivo requires the elimination of a high-temperature incubation step; instead, incubation should be carried out under physiological conditions. To improve the reactivity of CNVK mediated photo-cross-link induced deamination of cytosine under physiological conditions, an evaluation of base pairing in cytosine was carried out with respect to its deamination. Guanine was replaced with 4 different counter bases (inosine, 2-aminopurine, 5-nitroindole, and nebularine), showing distinct hydrogen bonding patterns with target cytosine, which was incorporated at the -1 position with respect to CNVK in the CNVK-modified photo-responsive oligodeoxyribonucleotides to ascertain the role of hydrogen bonding in deamination under physiological conditions. Among the counter bases, inosine showed the highest acceleration towards the photo-induced deamination reaction.
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Affiliation(s)
- Siddhant Sethi
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan.
| | - Minako Ooe
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan.
| | - Takashi Sakamoto
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan.
| | - Kenzo Fujimoto
- School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292, Japan.
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8
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Khalili B. A quantum chemical insight to intermolecular hydrogen bonding interaction between cytosine and nitrosamine: Structural and energetic investigations. J Mol Struct 2016. [DOI: 10.1016/j.molstruc.2015.11.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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9
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Zhang X, Zhao Y, Yan H, Cao Z, Mo Y. Combined QM(DFT)/MM molecular dynamics simulations of the deamination of cytosine by yeast cytosine deaminase (yCD). J Comput Chem 2016; 37:1163-74. [DOI: 10.1002/jcc.24306] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 01/04/2016] [Accepted: 01/05/2016] [Indexed: 12/16/2022]
Affiliation(s)
- Xin Zhang
- State Key Laboratory of Chemical Resource Engineering, Institute of Materia Medica, College of Science, Beijing University of Chemical Technology; Beijing 100029 China
- Department of Chemistry; Western Michigan University; Kalamazoo Michigan 49008
| | - Yuan Zhao
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry College of Chemistry and Chemical Engineering, Xiamen University; Xiamen 360015 China
- The Key Laboratory of Natural Medicine and Immuno-Engineering, Henan University; Kaifeng 475004 China
| | - Honggao Yan
- Department of Biochemistry; The Center for Biological Modeling, Michigan State University; East Lansing Michigan 48824
- Department of Chemistry; The Center for Biological Modeling, Michigan State University; East Lansing Michigan 48824
| | - Zexing Cao
- State Key Laboratory of Physical Chemistry of Solid Surfaces and Fujian Provincial Key Laboratory of Theoretical and Computational Chemistry College of Chemistry and Chemical Engineering, Xiamen University; Xiamen 360015 China
| | - Yirong Mo
- Department of Chemistry; Western Michigan University; Kalamazoo Michigan 49008
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10
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Manta B, Raushel FM, Himo F. Reaction Mechanism of Zinc-Dependent Cytosine Deaminase from Escherichia coli: A Quantum-Chemical Study. J Phys Chem B 2014; 118:5644-52. [DOI: 10.1021/jp501228s] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Bianca Manta
- Department
of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-106
91 Stockholm, Sweden
| | - Frank M. Raushel
- Department of Chemistry, Texas A&M University, P.O. Box 30012, College Station, Texas 77842-3012, United States
| | - Fahmi Himo
- Department
of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-106
91 Stockholm, Sweden
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11
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Duarte F, Amrein BA, Kamerlin SCL. Modeling catalytic promiscuity in the alkaline phosphatase superfamily. Phys Chem Chem Phys 2013; 15:11160-77. [PMID: 23728154 PMCID: PMC3693508 DOI: 10.1039/c3cp51179k] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Accepted: 05/02/2013] [Indexed: 12/19/2022]
Abstract
In recent years, it has become increasingly clear that promiscuity plays a key role in the evolution of new enzyme function. This finding has helped to elucidate fundamental aspects of molecular evolution. While there has been extensive experimental work on enzyme promiscuity, computational modeling of the chemical details of such promiscuity has traditionally fallen behind the advances in experimental studies, not least due to the nearly prohibitive computational cost involved in examining multiple substrates with multiple potential mechanisms and binding modes in atomic detail with a reasonable degree of accuracy. However, recent advances in both computational methodologies and power have allowed us to reach a stage in the field where we can start to overcome this problem, and molecular simulations can now provide accurate and efficient descriptions of complex biological systems with substantially less computational cost. This has led to significant advances in our understanding of enzyme function and evolution in a broader sense. Here, we will discuss currently available computational approaches that can allow us to probe the underlying molecular basis for enzyme specificity and selectivity, discussing the inherent strengths and weaknesses of each approach. As a case study, we will discuss recent computational work on different members of the alkaline phosphatase superfamily (AP) using a range of different approaches, showing the complementary insights they have provided. We have selected this particular superfamily, as it poses a number of significant challenges for theory, ranging from the complexity of the actual reaction mechanisms involved to the reliable modeling of the catalytic metal centers, as well as the very large system sizes. We will demonstrate that, through current advances in methodologies, computational tools can provide significant insight into the molecular basis for catalytic promiscuity, and, therefore, in turn, the mechanisms of protein functional evolution.
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Affiliation(s)
- Fernanda Duarte
- Uppsala University, Science for Life Laboratory (SciLifeLab), Cell and Molecular Biology, Uppsala, Sweden. ; ;
| | - Beat Anton Amrein
- Uppsala University, Science for Life Laboratory (SciLifeLab), Cell and Molecular Biology, Uppsala, Sweden. ; ;
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12
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Neves RPP, Sousa SF, Fernandes PA, Ramos MJ. Parameters for Molecular Dynamics Simulations of Manganese-Containing Metalloproteins. J Chem Theory Comput 2013; 9:2718-32. [DOI: 10.1021/ct400055v] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Affiliation(s)
- Rui P. P. Neves
- REQUIMTE,
Departamento de Química e Bioquímica,
Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, s/n, 4169-007 Porto, Portugal
| | - Sérgio F. Sousa
- REQUIMTE,
Departamento de Química e Bioquímica,
Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, s/n, 4169-007 Porto, Portugal
| | - Pedro A. Fernandes
- REQUIMTE,
Departamento de Química e Bioquímica,
Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, s/n, 4169-007 Porto, Portugal
| | - Maria J. Ramos
- REQUIMTE,
Departamento de Química e Bioquímica,
Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, s/n, 4169-007 Porto, Portugal
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13
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D'Ordine RL, Linger RS, Thai CJ, Davisson VJ. Catalytic zinc site and mechanism of the metalloenzyme PR-AMP cyclohydrolase. Biochemistry 2012; 51:5791-803. [PMID: 22741521 DOI: 10.1021/bi300391m] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
The enzyme N(1)-(5'-phosphoribosyl) adenosine-5'-monophosphate cyclohydrolase (PR-AMP cyclohydrolase) is a Zn(2+) metalloprotein encoded by the hisI gene. It catalyzes the third step of histidine biosynthesis, an uncommon ring-opening of a purine heterocycle for use in primary metabolism. A three-dimensional structure of the enzyme from Methanobacterium thermoautotrophicum has revealed that three conserved cysteine residues occur at the dimer interface and likely form the catalytic site. To investigate the functions of these cysteines in the enzyme from Methanococcus vannielii, a series of biochemical studies were pursued to test the basic hypothesis regarding their roles in catalysis. Inactivation of the enzyme activity by methyl methane thiosulfonate (MMTS) or 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB) also compromised the Zn(2+) binding properties of the protein inducing loss of up to 90% of the metal. Overall reaction stoichiometry and the potassium cyanide (KCN) induced cleavage of the protein suggested that all three cysteines were modified in the process. The enzyme was protected from DTNB-induced inactivation by inclusion of the substrate N(1)-(5'-phosphoribosyl)adenosine 5'-monophosphate; (PR-AMP), while Mg(2+), a metal required for catalytic activity, enhanced the rate of inactivation. Site-directed mutations of the conserved C93, C109, C116 and the double mutant C109/C116 were prepared and analyzed for catalytic activity, Zn(2+) content, and reactivity with DTNB. Substitution of alanine for each of the conserved cysteines showed no measurable catalytic activity, and only the C116A was still capable of binding Zn(2+). Reactions of DTNB with the C109A/C116A double mutant showed that C93 is completely modified within 0.5 s. A model consistent with these data involves a DTNB-induced mixed disulfide linkage between C93 and C109 or C116, followed by ejection of the active site Zn(2+) and provides further evidence that the Zn(2+) coordination site involves the three conserved cysteine residues. The C93 reactivity is modulated by the presence of the Zn(2+) and Mg(2+) and substantiates the role of this residue as a metal ligand. In addition, Mg(2+) ligand binding site(s) indicated by the structural analysis were probed by site-directed mutagenesis of three key aspartate residues flanking the conserved C93 which were shown to have a functional impact on catalysis, cysteine activation, and metal (zinc) binding capacity. The unique amino acid sequence, the dynamic properties of the cysteine ligands involved in Zn(2+) coordination, and the requirement for a second metal (Mg(2+)) are discussed in the context of their roles in catalysis. The results are consistent with a Zn(2+)-mediated activation of H(2)O mechanism involving histidine as a general base that has features similar to but distinct from those of previously characterized purine and pyrimidine deaminases.
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Affiliation(s)
- Robert L D'Ordine
- Department of Medicinal Chemistry and Molecular Pharmacology, Purdue University, West Lafayette, IN 47907, USA
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14
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Wang J, Sklenak S, Liu A, Felczak K, Wu Y, Li Y, Yan H. Role of glutamate 64 in the activation of the prodrug 5-fluorocytosine by yeast cytosine deaminase. Biochemistry 2011; 51:475-86. [PMID: 22208667 DOI: 10.1021/bi201540z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Yeast cytosine deaminase (yCD) catalyzes the hydrolytic deamination of cytosine to uracil as well as the deamination of the prodrug 5-fluorocytosine (5FC) to the anticancer drug 5-fluorouracil. In this study, the role of Glu64 in the activation of the prodrug 5FC was investigated by site-directed mutagenesis, biochemical, nuclear magnetic resonance (NMR), and computational studies. Steady-state kinetics studies showed that the mutation of Glu64 causes a dramatic decrease in k(cat) and a dramatic increase in K(m), indicating Glu64 is important for both binding and catalysis in the activation of 5FC. (19)F NMR experiments showed that binding of the inhibitor 5-fluoro-1H-pyrimidin-2-one (5FPy) to the wild-type yCD causes an upfield shift, indicating that the bound inhibitor is in the hydrated form, mimicking the transition state or the tetrahedral intermediate in the activation of 5FC. However, binding of 5FPy to the E64A mutant enzyme causes a downfield shift, indicating that the bound 5FPy remains in an unhydrated form in the complex with the mutant enzyme. (1)H and (15)N NMR analysis revealed trans-hydrogen bond D/H isotope effects on the hydrogen of the amide of Glu64, indicating that the carboxylate of Glu64 forms two hydrogen bonds with the hydrated 5FPy. ONIOM calculations showed that the wild-type yCD complex with the hydrated form of the inhibitor 1H-pyrimidin-2-one is more stable than the initial binding complex, and in contrast, with the E64A mutant enzyme, the hydrated inhibitor is no longer favored and the conversion has a higher activation energy, as well. The hydrated inhibitor is stabilized in the wild-type yCD by two hydrogen bonds between it and the carboxylate of Glu64 as revealed by (1)H and (15)N NMR analysis. To explore the functional role of Glu64 in catalysis, we investigated the deamination of cytosine catalyzed by the E64A mutant by ONIOM calculations. The results showed that without the assistance of Glu64, both proton transfers before and after the formation of the tetrahedral reaction intermediate become partially rate-limiting steps. The results of the experimental and computational studies together indicate that Glu64 plays a critical role in both the binding and the chemical transformation in the conversion of the prodrug 5FC to the anticancer drug 5-fluorouracil.
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Affiliation(s)
- Jifeng Wang
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan 48824, United States
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15
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Das B, Baruah JB. Assemblies of cytosine within H-bonded network of adipic acid and citric acid. J Mol Struct 2011. [DOI: 10.1016/j.molstruc.2011.06.029] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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16
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Molecular Dynamics Simulations: Difficulties, Solutions and Strategies for Treating Metalloenzymes. CHALLENGES AND ADVANCES IN COMPUTATIONAL CHEMISTRY AND PHYSICS 2010. [DOI: 10.1007/978-90-481-3034-4_11] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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17
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Liu A, Wang J, Lu Z, Yao L, Li Y, Yan H. Hydrogen-bond detection, configuration assignment and rotamer correction of side-chain amides in large proteins by NMR spectroscopy through protium/deuterium isotope effects. Chembiochem 2009; 9:2860-71. [PMID: 18973166 DOI: 10.1002/cbic.200800467] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The configuration and hydrogen-bonding network of side-chain amides in a 35 kDa protein were determined by measuring differential and trans-hydrogen-bond H/D isotope effects by using the isotopomer-selective (IS)-TROSY technique, which leads to a reliable recognition and correction of erroneous rotamers that are frequently found in protein structures. First, the differential two-bond isotope effects on carbonyl (13)C' shifts, which are defined as Delta(2)Delta(13)C'(ND) = (2)Delta(13)C'(ND(E))-(2)Delta(13)C'(ND(Z)), provide a reliable means for the configuration assignment for side-chain amides, because environmental effects (hydrogen bonds and charges, etc.) are greatly attenuated over the two bonds that separate the carbon and hydrogen atoms, and the isotope effects fall into a narrow range of positive values. Second and more importantly, the significant variations in the differential one-bond isotope effects on (15)N chemical shifts, which are defined as Delta(1)Delta(15)N(D) = (1)Delta(15)N(D(E))-(1)Delta(15)N(D(Z)) can be correlated with hydrogen-bonding interactions, particularly those involving charged acceptors. The differential one-bond isotope effects are additive, with major contributions from intrinsic differential conjugative interactions between the E and Z configurations, H-bonding interactions, and charge effects. Furthermore, the pattern of trans-H-bond H/D isotope effects can be mapped onto more complicated hydrogen-bonding networks that involve bifurcated hydrogen-bonds. Third, the correlations between Delta(1)Delta(15)N(D) and hydrogen-bonding interactions afford an effective means for the correction of erroneous rotamer assignments of side-chain amides. Rotamer correction by differential isotope effects is not only robust, but also simple and can be applied to large proteins.
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Affiliation(s)
- Aizhuo Liu
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA.
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18
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Sousa SF, Fernandes PA, Ramos MJ. Enzyme Flexibility and the Catalytic Mechanism of Farnesyltransferase: Targeting the Relation. J Phys Chem B 2008; 112:8681-91. [DOI: 10.1021/jp711214j] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sérgio F. Sousa
- REQUIMTE, Departamento de Química, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto, Portugal
| | - Pedro A. Fernandes
- REQUIMTE, Departamento de Química, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto, Portugal
| | - Maria João Ramos
- REQUIMTE, Departamento de Química, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto, Portugal
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Yao L, Cukier RI, Yan H. Catalytic mechanism of guanine deaminase: an ONIOM and molecular dynamics study. J Phys Chem B 2007; 111:4200-10. [PMID: 17394305 DOI: 10.1021/jp0673056] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The catalytic mechanism of Bacillus subtilis guanine deaminase (bGD), a Zn metalloenzyme, has been investigated by a combination of quantum mechanical calculations using the multilayered ONIOM method and molecular dynamics simulations. In contrast to a previously proposed catalytic mechanism, which requires the bound guanine to assume a rare tautomeric state, the ONIOM calculations showed that the active-site residues of the enzyme do not affect the tautomeric state of guanine, and consequently the bound guanine is a tautomer that is the most abundant in aqueous solution. Two residues, Glutamate 55 and Aspartate 114, were found to play important roles in proton shuttling in the reaction. The proposed reaction path is initiated by proton transfer from a Zn-bound water to protonate Asp114. This process may be quite complex and rather dynamic in nature, as revealed by the molecular dynamics (MD) simulations, whereby another water may bridge the Zn-bound water and Asp114, which then is eliminated by positioning of guanine in the active site. The binding of guanine stabilizes protonated Asp114 by hydrogen bond formation. Asp114 can then transfer its proton to the N3 of the bound guanine, facilitating the nucleophilic attack on C2 of the guanine by the Zn-bound hydroxide to form a tetrahedral intermediate. This occurs with a rather low barrier. Glu55 then transfers a proton from the Zn-hydroxide to the amino group of the reaction intermediate and, at this point, the C2-N2 bond has lengthened by 0.2 A compared to guanine, making C2-N2 bond cleavage more facile. The C2-N2 bond breaks forming ammonia, with an energy barrier of approximately 8.8 kcal/mol. Ammonia leaves the active site, and xanthine is freed by the cleavage of the Zn-O2 bond, with a barrier approximately 8.4 kcal/mol. Along this reaction path, the highest barrier comes from C2-N2 bond cleavage, while the barrier from the cleavage of the Zn-O2 bond is slightly smaller. The Zn-O2 bond can be broken without the assistance of water during the release of xanthine.
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Affiliation(s)
- Lishan Yao
- Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA
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Yao L, Yan H, Cukier RI. A molecular dynamics study of the ligand release path in yeast cytosine deaminase. Biophys J 2007; 92:2301-10. [PMID: 17218460 PMCID: PMC1864842 DOI: 10.1529/biophysj.106.098921] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Yeast cytosine deaminase, a zinc metalloenzyme, catalyzes the deamination of cytosine to uracil. Experimental and computational evidence indicates that the rate-limiting step is product release, instead of the chemical reaction step. In this work, we use molecular dynamics to suggest ligand exit paths. Simulation at 300 K shows that the active site is well protected by the C-terminal helix (residues 150-158) and F-114 loop (residues 111-117) and that on the molecular dynamics timescale water does not flow in or out of the active site. In contrast, simulation at 320 K shows a significant increase in flexibility of the C-terminal helix and F-114 loop. The motions of these two regions at 320 K open the active site and permit water molecules to diffuse into and out of the active site through two paths with one much more favored than the other. Cytosine is pushed out of the active site by a restraint method in two directions specified by these two paths. In path 1 the required motion of the protein is local-involving only the C-terminal helix and F-114 loop-and two residues, F-114 and I-156, are identified that have to be moved away to let cytosine out; whereas in path 2, the protein has to rearrange itself much more extensively, and the changes are also much larger compared to the path 1 simulation.
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Affiliation(s)
- Lishan Yao
- Department of Chemistry, Michigan State University Center for Biological Modeling, East Lansing, Michigan 48824, USA
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Yao L, Yan H, Cukier RI. A Combined ONIOM Quantum Chemical−Molecular Dynamics Study of Zinc−Uracil Bond Breaking in Yeast Cytosine Deaminase. J Phys Chem B 2006; 110:26320-6. [PMID: 17181291 DOI: 10.1021/jp064301s] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A QM/MM method that combines ONIOM quantum chemistry and molecular dynamics is developed and applied to a step in the deamination of cytosine to uracil in yeast cytosine deaminase (yCD). A two-layer ONIOM calculation is used for the reaction complex, with an inner part treated at a high level for the chemical reaction (bond breaking) and a middle part treated at a lower level for relevant protein residues that are frozen in the quantum optimization. An outer layer (protein and solvent) is treated using MD. Configurations for the entire system are generated using MD and optimized with ONIOM. The method permits the use of high-level quantum calculations along with sufficient configurational sampling to approximate the potential of mean force for certain bond-breaking reactions. A previously proposed reaction mechanism for deamination (Sklenak, S.; Yao, L. S.; Cukier, R. I.; Yan, H. G. J. Am. Chem. Soc. 2004, 126, 14879) requires breaking the bond between a catalytic zinc and the O4 of uracil in order to permit product release. Using an ONIOM approach, direct bond cleavage was found to be energetically unfavorable. In the work presented here, the combined ONIOM MD method is used to show that the barrier for bond cleavage is small, approximately 3 kcal/mol, and, consequently, should not be the rate-limiting step in the reaction.
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Affiliation(s)
- Lishan Yao
- Department of Chemistry, and MSU Center for Biological Modeling, Michigan State University, East Lansing, Michigan 48824, USA
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Sousa SF, Fernandes PA, Ramos MJ. Effective tailor-made force field parameterization of the several Zn coordination environments in the puzzling FTase enzyme: opening the door to the full understanding of its elusive catalytic mechanism. Theor Chem Acc 2006. [DOI: 10.1007/s00214-006-0170-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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