| Autor: |
Stack TMM; Carl R. Woese Institute for Genomic Biology , University of Illinois , Urbana , Illinois 61801 , United States., Morrison KN; Drury University , Springfield , Missouri 65802 , United States., Dettmer TM; Drury University , Springfield , Missouri 65802 , United States., Wille B; Department of Biological Sciences , Salisbury University , Salisbury , Maryland 21801 , United States., Kim C; Department of Biological Sciences , Salisbury University , Salisbury , Maryland 21801 , United States., Joyce R; Department of Biological Sciences , Salisbury University , Salisbury , Maryland 21801 , United States., Jermain M; Department of Biological Sciences , Salisbury University , Salisbury , Maryland 21801 , United States., Naing YT; Department of Biological Sciences , Salisbury University , Salisbury , Maryland 21801 , United States., Bhatti K; Department of Biological Sciences , Salisbury University , Salisbury , Maryland 21801 , United States., Francisco BS; Carl R. Woese Institute for Genomic Biology , University of Illinois , Urbana , Illinois 61801 , United States., Carter MS; 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., Gerlt JA; 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. |
| Abstrakt: |
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 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 b 561 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 . |
