Functional and ligand binding studies of NAD(P)H hydrate dehydratase enzyme from vancomycin-resistant Staphylococcus aureus by NMR spectroscopic approach, including saturation transfer difference (STD-NMR) spectroscopy.

NADH and NADPH are labile coenzymes that undergo hydration by enzymatic reaction or by heat at 5,6 double bond, and convert into non-functional hydrates, NADHX and NADPHX, respectively. The NAD(P)H hydrate dehydratase enzyme catalyzes the dehydration of S-NADHX/S-NADPHX at the expense of ATP, and thus contributes in the nicotinamide nucleotide repair process. This enzyme is also known as "metabolite-proofreading enzyme". Herein, we report the molecular cloning and expression of this highly conserved enzyme of vancomycin-resistant Staphylococcus aureus (VRSA). Its functional and inhibition studies were performed for the first time by NMR spectroscopy. NMR studies showed the dehydration of S epimer of NADHX, in the presence of R-NADHX and cyc-NADHX, by NAD(P)H hydrate dehydratase. In addition, by employing the STD-NMR approach, a library of drugs and natural products (total 79) were evaluated for their binding interactions with the NAD(P)H hydrate dehydratase enzyme. Among them, seven compounds showed ligand-like interactions with the enzyme, and thus functional activity of the enzyme was again checked in the presence of each ligand. Compound 2 (Thiamine HCl) was found to fully inhibit the enzyme's function, and recognized as a potential inhibitor. Current study demonstrates that this enzyme deserves further studies as a potential drug target, as its inhibition can disrupt the normal metabolism of pathogenic VRSA.