Isolation and characterization of a veratrol : corrinoid protein methyl transferase from Acetobacterium dehalogenans

From 3-methoxyphenol-grown cells of Acetobacterium dehalogenans, an inducib le enzyme was purified that mediated the transfer of the methyl groups of v eratrol (1,2-dimethoxybenzene) to a corrinoid protein enriched from the sam e cells. In this reaction, veratrol was converted via 2-methoxyphenol to 1, 2-dihydroxybenzene. The veratrol:corrinoid protein methyl transferase, desi gnated MTIver, had an apparent molecular mass of about 32 kDa. With respect to the N-terminal amino acid sequence and other characteristics, MTIver is different from the vanillate:corrinoid protein methyl transferase (MTIvan) isolated earlier from the same bacterium. For the methyl transfer from ver atrol to tetrahydrofolate, two additional protein fractions were required, one of which contained a corrinoid protein. This protein was not identical with the corrinoid protein of the vanillate O-demethylase system. However, the latter corrinoid protein could also serve as methyl acceptor for the ve ratrol:corrinoid protein methyl transferase. MTIver catalyzed the demethyla tion of veratrol, 3,4-dimethoxybenzoate, 2-methoxyphenol, and 3-methoxyphen ol. Vanillate (3-methoxy-4-hydroxybenzoale), 2-methoxybenzoate, or 4-methox ybenzoate could not serve as substrates.