Crystal structure of a methyltransferase involved in the biosynthesis of gentamicin in complex with (1R,2S,3S,4R,6S)-4,6-diamino-3-{[3-deoxy-3-(methylamino)-alpha-D-glucopyranosyl]oxy}-2-hydroxycyclohexyl 2,6-diamino-2,6-dideoxy-alpha-D-glucopyranoside
