Neomycins are aminocyclitol antibiotics belonging to a broad spectrum of highly toxic antimicrobials and in this case, are shown to be produced by Streptomyces rubrolavendulae. Neomycin exists in two active forms of stereoisomers: neomycin B and neomycin C and a relatively inactive degenerate form in small quantities: neomycin A. Among many of its uses, neomycin was used to treat the illness tuberculosis but was deemed too toxic in its display of side effect.; it is now generally used to control infection during intestinal surgery. This pathway shows the biosynthesis of the active forms of neomycin: neomycin C and neomycin B from D-glucose. While the initial section of this pathway resembles the use of enzymes in similar pathways like the paromamine biosynthesis I and ribostamycin biosynthesis, the enzymes that are specific to the biosynthesis of neomycin are those involved in the five final steps of the pathway starting from ribostamycin. As shown in the pathway, these include UDP-GlcNAc: ribostamycin N-acetylglucosaminyltransferase, 2'-N-acetylparomamine deacetylase, paromamine 6'-oxidase, neamine transaminase NeoN, and radical SAM superfamily protein. It should be noted that the stereoisomer neomycin C is made first from which neomycin B is synthesized and this is an example of an epimerization reaction at C-5'' of neomycin C to B.

Neomycin Biosynthesis References