Function of coenzyme F420 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 pi-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.