Overexpression of the coenzyme-F420-dependent N5,N10-methylenetetrahydromethanopterin dehydrogenase gene from the hyperthermophilic Methanopyrus kandleri.

The mtd gene encoding coenzyme-F420-dependent N5,N10-methylenetetrahydromethanopterin dehydrogenase (Mtd) in the hyperthermophilic Methanopyrus kandleri has been cloned, sequenced and functionally overexpressed in Escherichia coli. The overproduced enzyme was purified in a 90% yield to apparent homogeneity by means of only one chromatographic step. Its thermostability properties and most of its catalytic properties were the same as those of the native enzyme purified directly from M. kandleri. Only the dependence of the activity on the concentration of lyotropic salts differed slightly. Northern blot analysis revealed that in M. kandleri the mtd gene is monocistronically transcribed.