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Characterizing a Novel L‐Ascorbate Metabolic Pathway in Bacteria
Author(s) -
Jermain Madison Danielle
Publication year - 2020
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2020.34.s1.07042
Subject(s) - cupriavidus necator , biochemistry , catabolism , enzyme , metabolic pathway , ralstonia , bacteria , chemistry , ascorbic acid , gene , biology , genetics , food science , polyhydroxyalkanoates
L‐Ascorbate, commonly known as Vitamin C, is a naturally abundant carbon source produced in high quantities by plants. The involvement of L‐ascorbate as an antioxidant in processes within the body systems of mammals is well studied, yet L‐ascorbate can also function as a carbon source for some bacterial species. Ralstonia eutropha H16 ( Cupriavidus necator H16) is a soil bacterium that stores excess carbon in bioplastic granules and catabolizes L‐ascorbate via a previously unknown metabolic pathway. Transcripts for eight genes were upregulated >50‐fold in R. eutropha cells grown with L‐ascorbate compared to fructose or succinate. Three encode homologs of enzymes in L‐lyxonate catabolism to α‐ketoglutarate. Based on annotated functions of the five remaining enzymes, a predicated pathway was hypothesized to generate a‐ketoglutarate from L‐ascorbate. Enzymes not homologous to the L‐lyxonate pathway enzymes were purified and characterized in vitro by collaborators. Mutant R. eutropha strains were generated, each lacking one of the eight genes, and displayed significant growth defects when grown with L‐ascorbate. Support for a novel pathway for L‐ascorbate catabolism increases our knowledge of related enzyme functions and the involvement of L‐ascorbate in the carbon cycle.