Biochemical and molecular characterization of 1-hydroxy-2-naphthoate dioxygenase from Nocardioides sp. KP7.
1-Hydroxy-2-naphthoate dioxygenase, which cleaves the singly hydroxylated aromatic ring, was purified from phenanthrene-degrading Nocardioides sp. strain KP7. The purified enzyme had a molecular mass of 45 kDa by SDS-polyacrylamide gel electrophoresis and 270 kDa by gel filtration chromatography. The apparent Km and kcat values of this enzyme for 1-hydroxy-2-naphthoate were 10 microM and 114 s-1, respectively. One mole of molecular oxygen was consumed when 1 mol of 1-hydroxy-2-naphthoate was oxidized. This enzyme contained 1 mol of Fe(II)/mol of the subunit and was inactivated by o-phenanthroline. The enzyme that had been inactivated by o-phenanthroline was reactivated by incubating with FeSO4 and ascorbic acid. Thus, Fe(II) was required for the enzyme to exhibit activity. The structural gene for this enzyme was screened from a cosmid library and then sequenced, the length of the 1-hydroxy-2-naphthoate gene being 1161 base pairs. The deduced amino acid sequence of this enzyme was different from those of other ring-cleaving dioxygenases that cleave the doubly hydroxylated aromatic ring.
Iwabuchi
T
T
Marine Biotechnology Institute, Kamaishi Laboratories, 3-75-1 Heita, Kamaishi, Iwate 026, Japan.
Harayama
S
S
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D003001:Cloning, Molecular; D049308:Dioxygenases; D004789:Enzyme Activation; D008969:Molecular Sequence Data; D009618:Nocardiaceae / Q000201:enzymology* / Q000235:genetics; D010105:Oxygenases / Q000235:genetics* / Q000378:metabolism*
D001426:Bacterial Proteins; D010105:Oxygenases; C111742:1-hydroxy-2-naphthoate dioxygenase; D049308:Dioxygenases