Structural highlights
Function
[ARAA_AZOBR] Catalyzes the NAD(P)(+)-dependent conversion of L-arabinose to L-arabino-gamma-lactone. Is involved in a degradation pathway of L-arabinose that allows A.brasilense to grow on L-arabinose as a sole carbon source. Prefers NADP(+) to NAD(+) as electron acceptor. Displays high catalytic efficiency for both L-arabinose and D-galactose in vitro. However, the enzyme appears to be involved in the metabolism of L-arabinose but not D-galactose in vivo. To a lesser extent, is also active on D-talose and D-xylose as substrates in vitro, but not with D-arabinose, D-glucose, D-ribose, L-xylose, L-mannose, L-lyxose, and D-fructose.[1]
Publication Abstract from PubMed
In Azospirillum brasilense, a gram-negative nitrogen-fixing bacterium, l-arabinose is converted to alpha-ketoglutarate through a nonphosphorylative metabolic pathway. In the first step in the pathway, l-arabinose is oxidized to l-arabino-gamma-lactone by NAD(P)-dependent l-arabinose 1-dehydrogenase (AraDH) belonging to the glucose-fructose oxidoreductase/inositol dehydrogenase/rhizopine catabolism protein (Gfo/Idh/MocA) family. Here, we determined the crystal structures of apo- and NADP-bound AraDH at 1.5 and 2.2 A resolutions, respectively. A docking model of l-arabinose and NADP-bound AraDH and structure-based mutational analyses suggest that Lys91 or Asp169 serves as a catalytic base and that Glu147, His153, and Asn173 are responsible for substrate recognition. In particular, Asn173 may play a role in the discrimination between l-arabinose and d-xylose, the C4 epimer of l-arabinose.
Structural insights into the catalytic and substrate recognition mechanisms of bacterial l-arabinose 1-dehydrogenase.,Watanabe Y, Iga C, Watanabe Y, Watanabe S FEBS Lett. 2019 May 6. doi: 10.1002/1873-3468.13424. PMID:31058311[2]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Watanabe S, Kodaki T, Makino K. Cloning, expression, and characterization of bacterial L-arabinose 1-dehydrogenase involved in an alternative pathway of L-arabinose metabolism. J Biol Chem. 2006 Feb 3;281(5):2612-23. Epub 2005 Dec 2. PMID:16326697 doi:http://dx.doi.org/M506477200
- ↑ Watanabe Y, Iga C, Watanabe Y, Watanabe S. Structural insights into the catalytic and substrate recognition mechanisms of bacterial l-arabinose 1-dehydrogenase. FEBS Lett. 2019 May 6. doi: 10.1002/1873-3468.13424. PMID:31058311 doi:http://dx.doi.org/10.1002/1873-3468.13424
