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Publication Abstract from PubMed

N-hydroxylating monooxygenases (NMOs) are involved in the biosynthesis of iron-chelating hydroxamate-containing siderophores that play a role in microbial virulence. These flavoenzymes catalyze the NADPH- and oxygen-dependent hydroxylation of amines, such as those found on the side chains of lysine and ornithine. In this work we report the biochemical and structural characterization of Nocardia farcinica Lys-monooxygenase (NbtG), which has similar biochemical properties to mycobacterial homologs. NbtG is also active on D-Lys although it binds L-Lys with a higher affinity. Differently from the ornithine monooxygenases PvdA, SidA and KtzI, NbtG can use both NADH and NADPH and is highly uncoupled, producing more superoxide and hydrogen peroxide than hydroxylated Lys. The crystal structure of NbtG solved at 2.4 A resolution revealed an unexpected protein conformation with a 30 degrees rotation of the NAD(P)H domain with respect to the FAD domain that precludes binding of the nicotinamide cofactor. This occluded structure may explain the biochemical properties of NbtG, specifically with regard to the substantial uncoupling and limited stabilization of the C4a-hydroperoxyflavin intermediate. Biological implications of these findings are discussed.

An Unprecedented NADPH Domain Conformation in Lysine Monooxygenase NbtG Provides Insights Into Uncoupling of Oxygen Consumption From Substrate Hydroxylation.,Binda C, Robinson RM, Martin Del Campo JS, Keul ND, Rodriguez PJ, Robinson HH, Mattevi A, Sobrado P J Biol Chem. 2015 Mar 23. pii: jbc.M114.629485. PMID:25802330^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.