Identification of both neoQ and neoB gene products involved in the biosynthesis of neomycin in Streptomyces fradiae

Abstract

Neomycin is a 2-deoxystreptamine containing aminocyclitol aminoglycoside antibiotic produced by Streptomyces fradiae BUWKH 66278. In previous work, both neoQ and neoB genes putatively involved in the biosynthesis of neomycin were heterologously expressed in E. coli as soluble His-tagged proteins as determined by SDS-PAGE and Western blot assays. In this study, the biochemical activities of both gene products were investigated using spectrophotometery, TLC and HPLC. Both NeoQ and NeoB proteins were involved in the conversion of paromamine to neamine, the pseudodisaccharide intermediate in the biosynthesis of neomycin. Both NeoQ and NeoB were identified as paromamine 6'-dehydrogenase and 6'-dihydroparomamine aminotransferase, respectively. Results obtained from this study will contribute to clarify the complete biosynthetic pathway to neomycin and the related antibiotics such as ribostamycin and butirosins.