Agmenellum quadruplicatum M.AquI, a novel modification methylase.

The complete type II modification methylase of Agmenellum quadruplicatum was cloned in Escherichia coli as an R.Sau3A fragment of approximately 4.5 kilobases. The coding sequence was contained in a stretch of 1,156 base pairs which was organized into two parallel, partly overlapping open reading frames of 248 and 139 codons. In vivo complementation experiments showed that the synthesis of both predicted peptides was required for full methylase activity. The amino acid sequences were considerably similar to regions of other deoxycytidylate methylases.