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A Combined Computational–Experimental Study on the Substrate Binding and Reaction Mechanism of Salicylic Acid Decarboxylase. Catalysts 2022. [DOI: 10.3390/catal12121577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Salicylic acid decarboxylase (SDC) from the amidohydrolase superfamily (AHS) catalyzes the reversible decarboxylation of salicylic acid to form phenol. In this study, the substrate binding mode and reaction mechanism of SDC were investigated using computational and crystallographic methods. Quantum chemical calculations show that the enzyme follows the general mechanism of AHS decarboxylases. Namely, the reaction begins with proton transfer from a metal-coordinated aspartic acid residue (Asp298 in SDC) to the C1 of salicylic acid, which is followed by the C–C bond cleavage, to generate the phenol product and release CO2. Interestingly, the calculations show that SDC is a Mg-dependent enzyme rather than the previously proposed Zn-dependent, and the substrate is shown to be bidentately coordinated to the metal center in the catalysis, which is also different from the previous proposal. These predictions are corroborated by the crystal structure of SDC solved in complex with the substrate analogue 2-nitrophenol. The mechanistic insights into SDC in the present study provide important information for the rational design of the enzyme.
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Gao X, Wu M, Zhang W, Li C, Guo RT, Dai Y, Liu W, Mao S, Lu F, Qin HM. Structural Basis of Salicylic Acid Decarboxylase Reveals a Unique Substrate Recognition Mode and Access Channel. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2021; 69:11616-11625. [PMID: 34553918 DOI: 10.1021/acs.jafc.1c04091] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Salicylic acid (SA) decarboxylase from Trichosporon moniliiforme (TmSdc), which reversibly catalyses the decarboxylation of SA to yield phenol, is of significant interest because of its potential for the production of benzoic acid derivatives under environmentally friendly reaction conditions. TmSdc showed a preference for C2 hydroxybenzoate derivatives, with kcat/Km of SA being 3.2 × 103 M-1 s-1. Here, we presented the first crystal structures of TmSdc, including a complex with SA. The three conserved residues of Glu8, His169, and Asp298 are the catalytic residues within the TIM-barrel domain of TmSdc. Trp239 forms a unique hydrophobic recognition site by interacting with the phenyl ring of SA, while Arg235 is responsible for recognizing the hydroxyl group at the C2 of SA via hydrogen bond interactions. Using a semi-rational combinatorial active-site saturation test, we obtained the TmSdc mutant MT3 (Y64T/P191G/F195V/E302D), which exhibited a 26.4-fold increase in kcat/Km with SA, reaching 8.4 × 104 M-1 s-1. Steered molecular dynamics simulations suggested that the structural changes in MT3 relieved the steric hindrance within the substrate access channel and enlarged the substrate-binding pocket, leading to the increased activity by improving substrate access. Our data elucidate the unique substrate recognition mode and the substrate entrance tunnel of SA decarboxylase.
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Affiliation(s)
- Xin Gao
- Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, No. 29, 13th Avenue, Tianjin 300457, China
| | - Mian Wu
- Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, No. 29, 13th Avenue, Tianjin 300457, China
| | - Wei Zhang
- Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, No. 29, 13th Avenue, Tianjin 300457, China
| | - Chao Li
- Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, No. 29, 13th Avenue, Tianjin 300457, China
| | - Rey-Ting Guo
- State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan 430062, P. R. China
| | - Yujie Dai
- Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, No. 29, 13th Avenue, Tianjin 300457, China
| | - Weidong Liu
- Industrial Enzymes National Engineering Laboratory, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
| | - Shuhong Mao
- Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, No. 29, 13th Avenue, Tianjin 300457, China
| | - Fuping Lu
- Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, No. 29, 13th Avenue, Tianjin 300457, China
| | - Hui-Min Qin
- Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, No. 29, 13th Avenue, Tianjin 300457, China
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Sheng X, Himo F. Mechanisms of metal-dependent non-redox decarboxylases from quantum chemical calculations. Comput Struct Biotechnol J 2021; 19:3176-3186. [PMID: 34141138 PMCID: PMC8187880 DOI: 10.1016/j.csbj.2021.05.044] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 05/24/2021] [Accepted: 05/24/2021] [Indexed: 11/18/2022] Open
Abstract
Quantum chemical calculations are today an extremely valuable tool for studying enzymatic reaction mechanisms. In this mini-review, we summarize our recent work on several metal-dependent decarboxylases, where we used the so-called cluster approach to decipher the details of the reaction mechanisms, including elucidation of the identity of the metal cofactors and the origins of substrate specificity. Decarboxylases are of growing potential for biocatalytic applications, as they can be used in the synthesis of novel compounds of, e.g., pharmaceutical interest. They can also be employed in the reverse direction, providing a strategy to synthesize value‐added chemicals by CO2 fixation. A number of non-redox metal-dependent decarboxylases from the amidohydrolase superfamily have been demonstrated to have promiscuous carboxylation activities and have attracted great attention in the recent years. The computational mechanistic studies provide insights that are important for the further modification and utilization of these enzymes in industrial processes. The discussed enzymes are: 5‐carboxyvanillate decarboxylase, γ‐resorcylate decarboxylase, 2,3‐dihydroxybenzoic acid decarboxylase, and iso-orotate decarboxylase.
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Key Words
- 2,3-DHBD, 2,3‐dihydroxybenzoic acid decarboxylase
- 2,6-DHBD, 2,6‐dihydroxybenzoic acid decarboxylase
- 2-NR, 2-nitroresorcinol
- 5-CV, 5-carboxyvanillate
- 5-NV, 5-nitrovanillate
- 5caU, 5-carboxyuracil
- AHS, amidohydrolase superfamily
- Biocatalysis
- Decarboxylase
- Density functional theory
- IDCase, iso-orotate decarboxylase
- LigW, 5‐carboxyvanillate decarboxylase
- MIMS, membrane inlet mass spectrometry
- QM/MM, quantum mechanics/molecular mechanics
- Reaction mechanism
- Transition state
- γ-RS, γ-resorcylate
- γ-RSD, γ‐resorcylate decarboxylase
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Affiliation(s)
- Xiang Sheng
- National Engineering Laboratory for Industrial Enzymes and Tianjin Engineering Research Center of Biocatalytic Technology, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, and National Technology Innovation Center for Synthetic Biology, Tianjin 300308, PR China
| | - Fahmi Himo
- Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, SE-10691 Stockholm, Sweden
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