6jnj
From Proteopedia
Crystal structure of Azospirillum brasilense L-arabinose 1-dehydrogenase (apo-form)
Structural highlights
FunctionARAA_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 PubMedIn 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
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