Structure, mechanism, and evolution of the last step in vitamin C biosynthesis

• Published in: Nature communications 2024-05, Vol.15 (1), p.4158-4158, Article 4158
• Main Authors: Boverio, Alessandro, Jamil, Neelam, Mannucci, Barbara, Mascotti, Maria Laura, Fraaije, Marco W., Mattevi, Andrea
• Format: Article
• Language: English
• Subjects: 631/45/607/1168; 631/535/1266; 631/92/60; 82/16; 82/80; 82/83; Amino acids; Animals; Ascorbic acid; Ascorbic Acid - biosynthesis; Ascorbic Acid - metabolism; Biosynthesis; Catalytic Domain; Crystallography; Crystallography, X-Ray; Evolution; Evolution, Molecular; Flavin; Fungi; Humanities and Social Sciences; Kinetics; Models, Molecular; multidisciplinary; Mutagenesis; Oxidation; Oxidation-Reduction; Oxidoreductases - chemistry; Oxidoreductases - genetics; Oxidoreductases - metabolism; Photosynthesis; Phylogeny; Science; Science (multidisciplinary); Stereoselectivity; Substrate preferences; Substrate Specificity; Substrates; Vitamin C
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-48410-1

Photosynthetic organisms, fungi, and animals comprise distinct pathways for vitamin C biosynthesis. Besides this diversity, the final biosynthetic step consistently involves an oxidation reaction carried out by the aldonolactone oxidoreductases. Here, we study the origin and evolution of the diversified activities and substrate preferences featured by these flavoenzymes using molecular phylogeny, kinetics, mutagenesis, and crystallographic experiments. We find clear evidence that they share a common ancestor. A flavin-interacting amino acid modulates the reactivity with the electron acceptors, including oxygen, and determines whether an enzyme functions as an oxidase or a dehydrogenase. We show that a few side chains in the catalytic cavity impart the reaction stereoselectivity. Ancestral sequence reconstruction outlines how these critical positions were affixed to specific amino acids along the evolution of the major eukaryotic clades. During Eukarya evolution, the aldonolactone oxidoreductases adapted to the varying metabolic demands while retaining their overarching vitamin C-generating function. Photosynthetic organisms, fungi, and animals contain distinct pathways for vitamin C biosynthesis, but the final biosynthetic step consistently involves an oxidation reaction catalysed by the aldonolactone oxidoreductases. Here, the authors investigate the origin and evolution of the diversified activities and substrate preferences featured by these enzymes using different methods and find evidence that they share a common ancestor.