CLONING, SEQUENCING AND EXPRESSION OF THE GENES ENCODING THE SODIUM TRANSLOCATING N-5-METHYLTETRAHYDROMETHANOPTERIN-COENZYME-M METHYLTRANSFERASE OF THE METHYLOTROPHIC ARCHAEON METHANOSARCINA-MAZEI GO1

The N-5-methyltetrahydromethanopterin:coenzyme M methyltransferase of Methanosarcina mazei Go1 is a membrane-associated, corrinoid-containin g protein that uses a transmethylation reaction to drive an energy-con serving sodium ion pump. The eight open reading frames encoding the ei ght different subunits of the methyltransferase were identified and se quenced. All of these subunits are shown to be heterologously expresse d in minicells of the Escherichia coli mutant DK6. Sequence comparison s with the methyltransferases of thermophilic and hypothermophilic met hanogenic archaea are presented. The participation of the gene product of mtrD in sodium ion translocation as well as a consensus sequence o f a corrinoid binding motif in MtrA are discussed. (C) 1998 Federation of European Biochemical Societies.