Catalyzes the transfer of a methyl group to L-homocysteine resulting in methionine formation. Can use methylcobalamin and methylcobinamide as methyl donors, but methylcobalamin is not considered to be the physiological substrate. It was proposed that, in vivo, a so-far-unidentified enzyme catalyzes methyltransfer from 5-methyltetrahydromethanopterin (5-CH3-H4MPT) to a corrinoid protein, and that the MetE gene product catalyzes the further transfer to L-homocysteine. Is not active with L-cysteine, coenzyme M, coenzyme B, glutathione or dithiothreitol as substrate. Binds 1 zinc ion per subunit. Is activated by phosphates. Optimum pH is 7.0-8.0. Optimum temperature is 65 degrees Celsius. At this temperature, the enzyme is rapidly inactivated. Amino-acid biosynthesis; L-methionine biosynthesis via de novo pathway. Belongs to the archaeal MetE family. Extended N-terminus.