Function of Coenzyme F(420) in Aerobic Catabolism of 2,4,6-Trinitrophenol and 2,4-Dinitrophenol by Nocardioides simplex FJ2-1A

2,4,6-Trinitrophenol (picric acid) and 2,4-dinitrophenol were readily biodegraded by the strain Nocardioides simplex FJ2-1A. Aerobic bacterial degradation of these π-electron-deficient aromatic compounds is initiated by hydrogenation at the aromatic ring. A two-component enzyme system was identified which catalyzes hydride transfer to picric acid and 2,4-dinitrophenol. Enzymatic activity was dependent on NADPH and coenzyme F(420). The latter could be replaced by an authentic preparation of coenzyme F(420) from Methanobacterium thermoautotrophicum. One of the protein components functions as a NADPH-dependent F(420) reductase. A second component is a hydride transferase which transfers hydride from reduced coenzyme F(420) to the aromatic system of the nitrophenols. The N-terminal sequence of the F(420) reductase showed high homology with an F(420)-dependent NADP reductase found in archaea. In contrast, no N-terminal similarity to any known protein was found for the hydride-transferring enzyme.