Investigation of lysine: N-hydroxylation in the biosynthesis of the siderophore aerobactin

N-Ethylmaleimide was found to inhibit both pyruvate oxidation and lysine: N6-hydroxylation catalyzed by an enzyme system derived from Aerobacter aerogenes 62-1. Studies of pyruvate utilization in the presence and absence of lysine indicated a 1:1 stoichiometric relationship between consumption of pyruvate and production of N6-hydroxylation. Similar studies with an Escherichia coli mutant enzyme system revealed a 2:1 stoichiometric relationship between the above-mentioned processes. The formation of a nitrone derivative by interaction of N6-hydroxylysine with pyruvate has been suggested to provide the basis for the consumption of an additional mole of pyruvate in the E. coli enzyme system. Phenylhydrazine and 6-diazo-5-oxo-l-norleucine, the former after standing for appropriate periods, have been found to inhibit lysine: N6-hydroxylation reaction. The implications of these observations to the mechanism(s) operative in lysine: N6-hydroxylation are discussed.