OVEREXPRESSION OF THE COENZYME-F-420-DEPENDENT N-5,N-10-METHYLENETETRAHYDROMETHANOPTERIN DEHYDROGENASE GENE FROM THE HYPERTHERMOPHILIC METHANOPYRUS-KANDLERI

The mtd gene encoding coenzyme-F-420-dependent N-5,N-10-methylenetetra hydromethanopterin dehydrogenase (Mtd) in the hyperthermophilic Methan opyrus kandleri has been cloned, sequenced and functionally overexpres sed in Escherichia cell. The overproduced enzyme was purified in a 90% yield to apparent homogeneity by means of only one chromatographic st ep. Its thermostability properties and most of its catalytic propertie s 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.