Unusual NADPH conformation in the crystal structure of a cinnamyl alcohol dehydrogenase from Helicobacter pylori in complex with NADP(H) and substrate docking analysis

Cinnamyl alcohol dehydrogenase is a zinc- and NADPH-dependent dehydrogenase catalyzing the reversible conversion of p-hydroxycinnamaldehydes to their corresponding hydroxycinnamyl alcohols. A CAD homolog from Helicobacter pylori (HpCAD) possesses broad substrate specificities like the plant CADs and additionally a dismutation activity converting benzaldehyde to benzyl alcohol and benzoic acid. We have determined the crystal structure of HpCAD complexed with NADP(H) at 2.18 Å resolution to get a better understanding of this class of CAD outside of plants. The structure of HpCAD is highly homologous to the sinapyl alcohol dehydrogenase and the plant CAD with well-conserved residues involved in catalysis and zinc binding. However, the NADP(H) binding mode of the HpCAD has been found to be significantly different from those of plant CADs.Structured summary of protein interactionsHpCAD and HpCADbind by x-ray crystallography (View interaction)

► The binary structure of HpCAD complex NADP(H) is solved at 2.18 Å. ► An unusual conformation of the 2′phosphate group of the NADPH, not seen in other CAD structures, was found. ► Docking calculations showed that the substrate is stacked between the aromatic side chains of Tyr116 and Phe114.