1
|
Li RN, Chen SL. Recent Insights into the Reaction Mechanisms of Non-Heme Diiron Enzymes Containing Oxoiron(IV) Complexes. Chembiochem 2024:e202400788. [PMID: 39508533 DOI: 10.1002/cbic.202400788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2024] [Revised: 11/05/2024] [Accepted: 11/06/2024] [Indexed: 11/15/2024]
Abstract
Oxoiron(IV) complexes are key intermediates in the catalytic reactions of some non-heme diiron enzymes. These enzymes, across various subfamilies, activate dioxygen to generate high-valent diiron-oxo species, which, in turn, drive the activation of substrates and mediate a variety of challenging oxidative transformations. In this review, we summarize the structures, formation mechanisms, and functions of high-valent diiron-oxo intermediates in eight representative diiron enzymes (sMMO, RNR, ToMO, MIOX, PhnZ, SCD1, AlkB, and SznF) spanning five subfamilies. We also categorize and analyze the structural and mechanistic differences among these enzymes.
Collapse
Affiliation(s)
- Rui-Ning Li
- Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, China
| | - Shi-Lu Chen
- Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, China
| |
Collapse
|
2
|
de Visser SP, Wong HPH, Zhang Y, Yadav R, Sastri CV. Tutorial Review on the Set-Up and Running of Quantum Mechanical Cluster Models for Enzymatic Reaction Mechanisms. Chemistry 2024; 30:e202402468. [PMID: 39109881 DOI: 10.1002/chem.202402468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2024] [Accepted: 08/07/2024] [Indexed: 10/09/2024]
Abstract
Enzymes turnover substrates into products with amazing efficiency and selectivity and as such have great potential for use in biotechnology and pharmaceutical applications. However, details of their catalytic cycles and the origins surrounding the regio- and chemoselectivity of enzymatic reaction processes remain unknown, which makes the engineering of enzymes and their use in biotechnology challenging. Computational modelling can assist experimental work in the field and establish the factors that influence the reaction rates and the product distributions. A popular approach in modelling is the use of quantum mechanical cluster models of enzymes that take the first- and second coordination sphere of the enzyme active site into consideration. These QM cluster models are widely applied but often the results obtained are dependent on model choice and model selection. Herein, we show that QM cluster models can give highly accurate results that reproduce experimental product distributions and free energies of activation within several kcal mol-1, regarded that large cluster models with >300 atoms are used that include key hydrogen bonding interactions and charged residues. In this tutorial review, we give general guidelines on the set-up and applications of the QM cluster method and discuss its accuracy and reproducibility. Finally, several representative QM cluster model examples on metal-containing enzymes are presented, which highlight the strength of the approach.
Collapse
Affiliation(s)
- Sam P de Visser
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom
- Department of Chemical Engineering, The University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom
- Department of Chemistry, Indian Institute of Technology Guwahati, Assam, 781039, India
| | - Henrik P H Wong
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom
- Department of Chemical Engineering, The University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom
| | - Yi Zhang
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom
- Department of Chemical Engineering, The University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom
| | - Rolly Yadav
- Department of Chemistry, Indian Institute of Technology Guwahati, Assam, 781039, India
| | - Chivukula V Sastri
- Department of Chemistry, Indian Institute of Technology Guwahati, Assam, 781039, India
| |
Collapse
|
3
|
Ali HS, de Visser SP. QM/MM Study Into the Mechanism of Oxidative C=C Double Bond Cleavage by Lignostilbene-α,β-Dioxygenase. Chemistry 2024; 30:e202304172. [PMID: 38373118 DOI: 10.1002/chem.202304172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 01/29/2024] [Accepted: 02/19/2024] [Indexed: 02/21/2024]
Abstract
The enzymatic biosynthesis of fragrance molecules from lignin fragments is an important reaction in biotechnology for the sustainable production of fine chemicals. In this work we investigated the biosynthesis of vanillin from lignostilbene by a nonheme iron dioxygenase using QM/MM and tested several suggested proposals via either an epoxide or dioxetane intermediate. Binding of dioxygen to the active site of the protein results in the formation of an iron(II)-superoxo species with lignostilbene cation radical. The dioxygenase mechanism starts with electrophilic attack of the terminal oxygen atom of the superoxo group on the central C=C bond of lignostilbene, and the second-coordination sphere effects in the substrate binding pocket guide the reaction towards dioxetane formation. The computed mechanism is rationalized with thermochemical cycles and valence bond schemes that explain the electron transfer processes during the reaction mechanism. Particularly, the polarity of the protein and the local electric field and dipole moments enable a facile electron transfer and an exergonic dioxetane formation pathway.
Collapse
Affiliation(s)
- Hafiz Saqib Ali
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom
- Department of Chemical Engineering, The University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom
| | - Sam P de Visser
- Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Street, Manchester, M1 7DN, United Kingdom
- Department of Chemical Engineering, The University of Manchester, Oxford Road, Manchester, M13 9PL, United Kingdom
| |
Collapse
|
4
|
Li RN, Chen SL. Mechanistic Insights into the N-Hydroxylations Catalyzed by the Binuclear Iron Domain of SznF Enzyme: Key Piece in the Synthesis of Streptozotocin. Chemistry 2024; 30:e202303845. [PMID: 38212866 DOI: 10.1002/chem.202303845] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2023] [Revised: 01/10/2024] [Accepted: 01/11/2024] [Indexed: 01/13/2024]
Abstract
SznF, a member of the emerging family of heme-oxygenase-like (HO-like) di-iron oxidases and oxygenases, employs two distinct domains to catalyze the conversion of Nω-methyl-L-arginine (L-NMA) into N-nitroso-containing product, which can subsequently be transformed into streptozotocin. Using unrestricted density functional theory (UDFT) with the hybrid functional B3LYP, we have mechanistically investigated the two sequential hydroxylations of L-NMA catalyzed by SznF's binuclear iron central domain. Mechanism B primarily involves the O-O bond dissociation, forming Fe(IV)=O, induced by the H+/e- introduction to the FeA side of μ-1,2-peroxo-Fe2(III/III), the substrate hydrogen abstraction by Fe(IV)=O, and the hydroxyl rebound to the substrate N radical. The stochastic addition of H+/e- to the FeB side (mechanism C) can transition to mechanism B, thereby preventing enzyme deactivation. Two other competing mechanisms, involving the direct O-O bond dissociation (mechanism A) and the addition of H2O as a co-substrate (mechanism D), have been ruled out.
Collapse
Affiliation(s)
- Rui-Ning Li
- Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, China
| | - Shi-Lu Chen
- Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, 100081, China
| |
Collapse
|
5
|
Ushimaru R, Abe I. Unusual Dioxygen-Dependent Reactions Catalyzed by Nonheme Iron Enzymes in Natural Product Biosynthesis. ACS Catal 2022. [DOI: 10.1021/acscatal.2c05247] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Richiro Ushimaru
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
- ACT-X, Japan Science and Technology Agency (JST), Honcho, Kawaguchi, Saitama 332-0012, Japan
| | - Ikuro Abe
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
- Collaborative Research Institute for Innovative Microbiology, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
| |
Collapse
|
6
|
Wang Y, Dong L, Su H, Liu Y. Dioxygen Activation and N δ,N ε-Dihydroxylation Mechanism Involved in the Formation of N-Nitrosourea Pharmacophore in Streptozotocin Catalyzed by Nonheme Diiron Enzyme SznF. Inorg Chem 2022; 61:15721-15734. [PMID: 36148800 DOI: 10.1021/acs.inorgchem.2c02814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
SznF is a nonheme diiron-dependent enzyme that catalyzes the critical N-nitrosation involved in the formation of the N-nitrosourea moiety in the pancreatic cancer drug streptozotocin. The N-nitrosation contains two successive N-hydroxylation and N-nitrosation steps, which are carried out by two separate active sites, namely, the central domain and cupin domain. Recently, the crystal structure of SznF was obtained, and the central domain was proved to contain a diiron cofactor to catalyze the N-hydroxylation. In this work, to gain insights into the O2 activation and the successive N-hydroxylation mechanism, on the basis of the high-resolution crystal structure, the enzyme-substrate complex models were constructed, and a series of combined QM/MM calculations were performed. Based on our calculations, the activation of O2 starts from the diiron(II,III)-superoxo (S) to generate the diiron(IV)-oxo species (Q) via a diiron(III,III)-peroxo (P)-like transition state or unstable intermediate (P'), and species P' can be described as a hybridization of diiron(IV)-oxo species and diiron(III,III)-peroxo (P) owing to the long distances of Fe1-Fe2 (4.22 Å) and O1-O2 (1.89 Å), which is different from those of other nonheme diiron enzymes. In the following hydroxylation of Nδ and Nε, the Nδ-hydroxylation was confirmed to occur first, agreeing with the experimental observations. Because the diiron(IV)-oxo species (Q) is responsible for hydroxylation, the reaction follows the H-abstraction/OH rebound mechanism, and the first abstraction occurs on the Nδ-H rather than Nε-H, which may be attributed to the different orientation of Fe(IV)-oxo relative to N-H as well as the bond dissociation enthalpies of two N-H bonds. The hydroxylation of N-methyl-L-arginine does not employ the diiron(III,III)-hydroperoxo (P″) to trigger the electrophilic attack of the guanidine to directly form the N-O bond, as previously suggested. In addition, our calculations also revealed that the direct attack of the Fe(IV)═O unit to the Nδ of the substrate corresponds to a higher barrier than that in the H-abstraction/OH rebound mechanism. These results may provide useful information for understanding the formation of the di-hydroxylation intermediate involved in the biosynthesis of N-nitrosation.
Collapse
Affiliation(s)
- Yijing Wang
- School of Chemistry and Chemical Engineering, Shandong University, Jinan, Shandong 250100, China
| | - Lihua Dong
- School of Chemistry and Chemical Engineering, Qilu Normal University, Jinan, Shandong 250013, China
| | - Hao Su
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Science, Tianjin 300308, China
| | - Yongjun Liu
- School of Chemistry and Chemical Engineering, Shandong University, Jinan, Shandong 250100, China
| |
Collapse
|