The membrane-bound sorbosone dehydrogenase of Gluconacetobacter liquefaciens is a pyrroloquinoline quinone-dependent enzyme

Publication date: Available online 28 January 2020Source: Enzyme and Microbial TechnologyAuthor(s): Toshiharu Yakushi, Ryota Takahashi, Minenosuke Matsutani, Naoya Kataoka, Roque A. Hours, Yoshitaka Ano, Osao Adachi, Kazunobu MatsushitaAbstractMembrane-bound sorbosone dehydrogenase (SNDH) of Gluconacetobacter liquefaciens oxidizes L-sorbosone to 2-keto-L-gulonic acid (2KGLA), a key intermediate in vitamin C production. We constructed recombinant Escherichia coli and Gluconobacter strains harboring plasmids carrying the sndh gene from Ga. liquefaciens strain RCTMR10 to identify the prosthetic group of SNDH. The membranes of the recombinant E. coli showed L-sorbosone oxidation activity, only after the holo-enzyme formation with pyrroloquinoline quinone (PQQ), indicating that SNDH is a PQQ-dependent enzyme. The sorbosone-oxidizing respiratory chain was thus heterologously reconstituted in the E. coli membranes. The membranes that contained SNDH showed the activity of sorbosone : ubiquinone analogue oxidoreductase. These results suggest that the natural electron acceptor for SNDH is membranous ubiquinone, and it functions as the primary dehydrogenase in the sorbosone oxidation respiratory chain in Ga. liquefaciens. A biotransformation experiment showed L-sorbosone oxidation to 2KGLA in a nearly quantitative manner. Phylogenetic analysis for prokaryotic SNDH homologues revealed that they are found only in the Proteobacteria phylum and those of the Acetobacteraceae family are clust...
Source: Enzyme and Microbial Technology - Category: Biotechnology Source Type: research