|Hedges JB, Kuatsjah E, Du YL, Eltis LD, Ryan KS.
|Snapshots of the catalytic cycle of an O2, pyridoxal phosphate-dependent hydroxylase.
|ACS Chem Biol
|Enzymes that catalyze hydroxylation of unactivated carbons normally contain heme- and non-heme iron cofactors. By contrast, how a pyridoxal phosphate (PLP)-dependent enzyme could catalyze such a hydroxylation was unknown. Here, we investigate RohP, a PLP-dependent enzyme that converts L-arginine to (S)-4-hydroxy-2-ketoarginine. We determine that the RohP reaction consumes oxygen, with stoichiometric release of H2O2. To understand this unusual chemistry, we obtain ~1.5 Å resolution structures that capture intermediates along the catalytic cycle. Our data suggest that RohP carries out a four-electron oxidation and a stereospecific alkene hydration to give the (S)-configured product. Together with our earlier studies on an O2, PLP-dependent L-arginine oxidase, our work suggests that there is a shared pathway leading to both oxidized and hydroxylated products from L-arginine.