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. Binds 1 zinc ion per subunit. Amino-acid biosynthesis; L-methionine biosynthesis via de novo pathway. Belongs to the archaeal MetE family.