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The ether-cleaving methyltransferase of the strict anaerobe Acetobacterium dehalogenans: analysis of the zinc-binding site

2011; Oxford University Press; Volume: 318; Issue: 2 Linguagem: Inglês

10.1111/j.1574-6968.2011.02251.x

1574-6968

Sandra Studenik, Sandra Kreher, Gabriele Diekert,

Cassava research and cyanide

The anaerobic phenyl methyl ether cleavage in acetogenic bacteria is mediated by multicomponent enzyme systems designated O-demethylases. Depending on the growth substrate, different O-demethylases are induced in Acetobacterium dehalogenans. A vanillate- and a veratrol-O-demethylase of this organism have been described earlier. The methyltransferase I (MT I), a component of this enzyme system, catalyzes the ether cleavage and the transfer of the methyl group to a super-reduced corrinoid bound to a protein. The MT I of the vanillate- and veratrol-O-demethylase (MT Ivan and MT Iver) were found to be zinc-containing enzymes. By site-directed mutagenesis, putative zinc ligands were identified, from which the following unique zinc-binding motifs were derived: E-X14-E-X20-H for MT Ivan and D-X27-C-X39-C for MT Iver.