The ATP-dependent synthesis of factor 390 by cell-free extracts of Methanobacterium thermoautotrophicum (strain ΔH)

Cell-free extracts of Methanobacterium thermoautotrophicum (strain ΔH) converted the 8-OH-5-deazaflavin coenzyme F420 to factor 390, a 8-adenylyl derivative (F420-AMP). Activity was only observed upon exposure of the crude cell-free extract to oxygen. The ability to synthesize F390 was lost when crude cell-free extract was subsequently brought to an anaerobic reducing environment. The enzymatic reaction used ATP and oxidized coenzyme F420 as substrates and inorganic pyrophosphate was formed next to F390. GTP could be used instead of ATP resulting in a guanylylated derivative. The crude cell-free extract showed Km values of 154 μM for coenzyme F420 and 2.4 mM for ATP. A partially purified enzyme preparation exhibited a Keq of 0.32. In accordance, coenzyme F420 and ATP could be synthesized from F390 and PPi by the reverse reaction.