庆大霉素生物合成中4〞-C甲基形成过程的研究

Gentamicin is widely used in clinic, which contains four major components differing from methyl groups. The methyl groups have a significant impact on antibiotic activity and toxicity of gentamicin. However, gene encoding methyltransferse that acts on C-4'' of gentamicin remains obscure. Sequence analysis has predicted that genN was a methyltransferase in gentamicin biosynthetic pathway. To study the function of genN, it was disrupted in the gentamicin producers M. echinospora. In genN disrupting strains, the production of gentamicin C complex was abolished and 4''-demethyl-gentamicin C complex was obtained. The restoration of gentamicin by self complementation suggested that there was no polar effect in the mutants. These gene inactivation and complementation studies suggested that GenN is C-methyltransferase that acts on C-4'' in gentamicin biosynthesis.