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Dulchavsky M, Mitra R, Wu K, Li J, Boer K, Liu X, Zhang Z, Vasquez C, Clark CT, Funckes K, Shankar K, Bonnet-Zahedi S, Siddiq M, Sepulveda Y, Suhandynata RT, Momper JD, Calabrese AN, George O, Stull F, Bardwell JCA. Directed evolution unlocks oxygen reactivity for a nicotine-degrading flavoenzyme. Nat Chem Biol 2023; 19:1406-1414. [PMID: 37770699 PMCID: PMC10611581 DOI: 10.1038/s41589-023-01426-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 08/23/2023] [Indexed: 09/30/2023]
Abstract
The flavoenzyme nicotine oxidoreductase (NicA2) is a promising injectable treatment to aid in the cessation of smoking, a behavior responsible for one in ten deaths worldwide. NicA2 acts by degrading nicotine in the bloodstream before it reaches the brain. Clinical use of NicA2 is limited by its poor catalytic activity in the absence of its natural electron acceptor CycN. Without CycN, NicA2 is instead oxidized slowly by dioxygen (O2), necessitating unfeasibly large doses in a therapeutic setting. Here, we report a genetic selection strategy that directly links CycN-independent activity of NicA2 to growth of Pseudomonas putida S16. This selection enabled us to evolve NicA2 variants with substantial improvement in their rate of oxidation by O2. The encoded mutations cluster around a putative O2 tunnel, increasing flexibility and accessibility to O2 in this region. These mutations further confer desirable clinical properties. A variant form of NicA2 is tenfold more effective than the wild type at degrading nicotine in the bloodstream of rats.
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Affiliation(s)
- Mark Dulchavsky
- Howard Hughes Medical Institute and Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
- Cellular and Molecular Biology Program, University of Michigan, Ann Arbor, MI, USA
| | - Rishav Mitra
- Howard Hughes Medical Institute and Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Kevin Wu
- Howard Hughes Medical Institute and Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Joshua Li
- Howard Hughes Medical Institute and Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Karli Boer
- Department of Chemistry, Western Michigan University, Kalamazoo, MI, USA
| | - Xiaomeng Liu
- Howard Hughes Medical Institute and Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Zhiyao Zhang
- Department of Chemistry, Western Michigan University, Kalamazoo, MI, USA
| | - Cristian Vasquez
- Department of Chemistry, Western Michigan University, Kalamazoo, MI, USA
| | | | - Kaitrin Funckes
- Department of Chemistry, Western Michigan University, Kalamazoo, MI, USA
| | - Kokila Shankar
- Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA
| | - Selene Bonnet-Zahedi
- Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA
| | - Mohammad Siddiq
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
| | - Yadira Sepulveda
- School of Pharmacy and Pharmaceutical Science, University of California, San Diego, La Jolla, CA, USA
| | - Raymond T Suhandynata
- School of Pharmacy and Pharmaceutical Science, University of California, San Diego, La Jolla, CA, USA
- Department of Pathology, University of California, San Diego, La Jolla, CA, USA
| | - Jeremiah D Momper
- School of Pharmacy and Pharmaceutical Science, University of California, San Diego, La Jolla, CA, USA
| | - Antonio N Calabrese
- Astbury Centre for Structural Molecular Biology, S chool of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, UK
| | - Olivier George
- Department of Psychiatry, University of California, San Diego, La Jolla, CA, USA
| | - Frederick Stull
- Department of Chemistry, Western Michigan University, Kalamazoo, MI, USA
| | - James C A Bardwell
- Howard Hughes Medical Institute and Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA.
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Mumby EJ, Willoughby JA, Vasquez C, Delavari N, Zhang Z, Clark CT, Stull F. Binding Interface and Electron Transfer Between Nicotine Oxidoreductase and Its Cytochrome c Electron Acceptor. Biochemistry 2022; 61:2182-2187. [PMID: 36154019 PMCID: PMC10163435 DOI: 10.1021/acs.biochem.2c00472] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The enzyme nicotine oxidoreductase (NicA2) is a member of the flavoprotein amine oxidase family that uses a cytochrome c protein (CycN) as its oxidant instead of dioxygen, which is the oxidant used by most other members of this enzyme family. We recently identified a potential binding site for CycN on the surface of NicA2 through rigid body docking [J. Biol. Chem. 2022, 298 (8), 102251]. However, this potential binding interface has not been experimentally validated. In this paper, we used unnatural amino acid incorporation to probe the binding interface between NicA2 and CycN. Our results are consistent with a structural model of the NicA2-CycN complex predicted by protein-protein docking and AlphaFold, suggesting that this is the binding site for CycN on NicA2's surface. Based on additional mutagenesis of potentially redox active residues in NicA2, we propose that electron transfer from NicA2's flavin to CycN's heme occurs without the assistance of a protein-derived wire.
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Affiliation(s)
- Elizabeth J Mumby
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan 49008, United States
| | - Jamin A Willoughby
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan 49008, United States
| | - Cristian Vasquez
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan 49008, United States
| | - Niusha Delavari
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan 49008, United States
| | - Zhiyao Zhang
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan 49008, United States
| | - Christopher T Clark
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan 49008, United States
| | - Frederick Stull
- Department of Chemistry, Western Michigan University, Kalamazoo, Michigan 49008, United States
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