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Vargas JA, Sculaccio SA, Pinto APA, Pereira HD, Mendes LFS, Flores JF, Cobos M, Castro JC, Garratt RC, Leonardo DA. Structural insights into the Smirnoff-Wheeler pathway for vitamin C production in the Amazon fruit camu-camu. J Exp Bot 2024; 75:2754-2771. [PMID: 38224521 DOI: 10.1093/jxb/erae016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 01/12/2024] [Indexed: 01/17/2024]
Abstract
l-Ascorbic acid (AsA, vitamin C) is a pivotal dietary nutrient with multifaceted importance in living organisms. In plants, the Smirnoff-Wheeler pathway is the primary route for AsA biosynthesis, and understanding the mechanistic details behind its component enzymes has implications for plant biology, nutritional science, and biotechnology. As part of an initiative to determine the structures of all six core enzymes of the pathway, the present study focuses on three of them in the model species Myrciaria dubia (camu-camu): GDP-d-mannose 3',5'-epimerase (GME), l-galactose dehydrogenase (l-GalDH), and l-galactono-1,4-lactone dehydrogenase (l-GalLDH). We provide insights into substrate and cofactor binding and the conformational changes they induce. The MdGME structure reveals a distorted substrate in the active site, pertinent to the catalytic mechanism. Mdl-GalDH shows that the way in which NAD+ association affects loop structure over the active site is not conserved when compared with its homologue in spinach. Finally, the structure of Mdl-GalLDH is described for the first time. This allows for the rationalization of previously identified residues which play important roles in the active site or in the formation of the covalent bond with FAD. In conclusion, this study enhances our understanding of AsA biosynthesis in plants, and the information provided should prove useful for biotechnological applications.
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Affiliation(s)
- Jhon A Vargas
- São Carlos Institute of Physics, University of São Paulo, Avenida João Dagnone 1100, São Carlos, SP 13563-120, Brazil
| | - Susana A Sculaccio
- São Carlos Institute of Physics, University of São Paulo, Avenida João Dagnone 1100, São Carlos, SP 13563-120, Brazil
| | - Andressa P A Pinto
- São Carlos Institute of Physics, University of São Paulo, Avenida João Dagnone 1100, São Carlos, SP 13563-120, Brazil
| | - Humberto D'Muniz Pereira
- São Carlos Institute of Physics, University of São Paulo, Avenida João Dagnone 1100, São Carlos, SP 13563-120, Brazil
| | - Luis F S Mendes
- São Carlos Institute of Physics, University of São Paulo, Avenida João Dagnone 1100, São Carlos, SP 13563-120, Brazil
| | - Jhoao F Flores
- Institute of Biology, State University of Campinas, Rua Monteiro Lobato 255, Campinas, SP 13083-862, Brazil
| | - Marianela Cobos
- Unidad Especializada del Laboratorio de Investigación en Biotecnología (UELIB), Centro de Investigaciones de Recursos Naturales de la UNAP (CIRNA), Universidad Nacional de la Amazonia Peruana (UNAP), Psje. Los Paujiles S/N, 1600, Iquitos, Peru
- Departamento de Ciencias Biomédicas y Biotecnología, Facultad de Ciencias Biológicas, Universidad Nacional de la Amazonia Peruana (UNAP), Zungarococha, Ciudad Universitaria. Iquitos, Perú
| | - Juan C Castro
- Unidad Especializada del Laboratorio de Investigación en Biotecnología (UELIB), Centro de Investigaciones de Recursos Naturales de la UNAP (CIRNA), Universidad Nacional de la Amazonia Peruana (UNAP), Psje. Los Paujiles S/N, 1600, Iquitos, Peru
- Departamento de Ciencias Biomédicas y Biotecnología, Facultad de Ciencias Biológicas, Universidad Nacional de la Amazonia Peruana (UNAP), Zungarococha, Ciudad Universitaria. Iquitos, Perú
| | - Richard C Garratt
- São Carlos Institute of Physics, University of São Paulo, Avenida João Dagnone 1100, São Carlos, SP 13563-120, Brazil
| | - Diego A Leonardo
- São Carlos Institute of Physics, University of São Paulo, Avenida João Dagnone 1100, São Carlos, SP 13563-120, Brazil
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