Characterization of a heme-dependent catalase from Methanobrevibacter arboriphilus

Recently it was reported that methanogens of the genus Methanobrevibacter e xhibit catalase activity. This was surprising, since Methanobrevibacter spe cies belong to the order Methanobacteriales, which are known not to contain cytochromes and to lack the ability to synthesize heme, We report here tha t Methanobrevibacter arboriphilus strains AZ and DH1 contained catalase act ivity only when the growth medium was supplemented with hemin. The heme cat alase was purified and characterized, and the encoding gene was cloned. The amino acid sequence of the catalase from the methanogens is most similar t o that of Methanosarcina barkeri.