Research Article

Characterization of an l-Ascorbate Catabolic Pathway with Unprecedented Enzymatic Transformations

Published: 2020-1-29

Journal: Journal of the American Chemical Society

DOI: 10.1021/jacs.9b09863

Abstract

### Title Characterization of an l-Ascorbate Catabolic Pathway with Unprecedented Enzymatic Transformations ### Abstract l-Ascorbate (vitamin C) is ubiquitous in both our diet and the environment. Here we report that *Ralstonia eutropha* H16 (Cupriavidus necator ATCC 17699) uses l-ascorbate as a sole carbon source via a novel catabolic pathway. RNaseq identified eight candidate catabolic genes, sequence similarity networks, and genome neighborhood networks guided predictions for function of the encoded proteins, and the predictions were confirmed by in vitro assays and in vivo growth phenotypes of gene deletion mutants. l-Ascorbate, a lactone, is oxidized and ring-opened by enzymes in the cytochrome b561 and gluconolactonase families, respectively, to form 2,3-diketo-l-gulonate. A protein predicted to have a WD40-like fold catalyzes an unprecedented benzilic acid rearrangement involving migration of a carboxylate group to form 2-carboxy-l-lyxonolactone; the lactone is hydrolyzed by a member of the amidohydrolase superfamily to yield 2-carboxy-l-lyxonate. A member of the PdxA family of oxidative decarboxylases catalyzes a novel decarboxylation that uses NAD+ catalytically. The product, l-lyxonate, is catabolized to α-ketoglutarate by a previously characterized pathway. The pathway is found in hundreds of bacteria, including the pathogens *Pseudomonas aeruginosa* and *Acinetobacter baumannii*. ### Authors - Tyler M. M. Stack, Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois 61801, United States - Katelyn N. Morrison, Drury University, Springfield, Missouri 65802, United States - Thomas M. Dettmer, Drury University, Springfield, Missouri 65802, United States - Brendan Wille, Department of Biological Sciences, Salisbury University, Salisbury, Maryland 21801, United States - Chan Kim, Department of Biological Sciences, Salisbury University, Salisbury, Maryland 21801, United States - Ryan Joyce, Department of Biological Sciences, Salisbury University, Salisbury, Maryland 21801, United States - Madison Jermain, Department of Biological Sciences, Salisbury University, Salisbury, Maryland 21801, United States - Yadanar Than Naing, Department of Biological Sciences, Salisbury University, Salisbury, Maryland 21801, United States - Khadija Bhatti, Department of Biological Sciences, Salisbury University, Salisbury, Maryland 21801, United States - Brian San Francisco, Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois 61801, United States - Michael S. Carter, Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois 61801, United States; Department of Biological Sciences, Salisbury University, Salisbury, Maryland 21801, United States - John A. Gerlt, Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois 61801, United States; Departments of Biochemistry and Chemistry, University of Illinois, Urbana, Illinois 61801, United States ### Publication Details - **Journal:** Journal of the American Chemical Society - **Volume:** 142 - **Issue:** 4 - **Pages:** 1657–1661 - **Published on:** January 9, 2020 - **DOI:** [10.1021/jacs.9b09863](https://doi.org/10.1021/jacs.9b09863) ### Keywords - Lactones - Oxidation - Peptides and proteins - Rearrangement - Redox reactions ### Cited By This article is cited by 8 publications.

Faculty Members

  • Brian San Francisco - Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois 61801, United States
  • Brendan Wille - Department of Biological Sciences, Salisbury University, Salisbury, Maryland 21801, United States
  • Katelyn N. Morrison - Drury University, Springfield, Missouri 65802, United States
  • Madison Jermain - Department of Biological Sciences, Salisbury University, Salisbury, Maryland 21801, United States
  • Ryan Joyce - Department of Biological Sciences, Salisbury University, Salisbury, Maryland 21801, United States
  • Michael S. Carter - Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois 61801, United StatesDepartment of Biological Sciences, Salisbury University, Salisbury, Maryland 21801, United States
  • Chan Kim - Department of Biological Sciences, Salisbury University, Salisbury, Maryland 21801, United States
  • Khadija Bhatti - Department of Biological Sciences, Salisbury University, Salisbury, Maryland 21801, United States
  • Yadanar Than Naing - Department of Biological Sciences, Salisbury University, Salisbury, Maryland 21801, United States
  • Thomas M. Dettmer - Drury University, Springfield, Missouri 65802, United States
  • Tyler M. M. Stack - Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois 61801, United States
  • John A. Gerlt - Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois 61801, United StatesDepartments of Biochemistry and Chemistry, University of Illinois, Urbana, Illinois 61801, United States

Themes

  • Pathogen Biology
  • Enzymatic Transformations
  • Catabolism
  • Metabolic Pathways
  • Bacterial Metabolism

Categories

Download Article