Ribostamycin is an aminoglycoside-aminocyclitol antibiotic isolated from a streptomycete, Streptomyces ribosidificus, originally identified in a soil sample from Tsu City of Mie Prefecture in Japan.[1] It is made up of 3 ring subunits: 2-deoxystreptamine (DOS), neosamine C, and ribose.[2] Ribostamycin, along with other aminoglycosides with the DOS subunit, is an important broad-spectrum antibiotic with important use against human immunodeficiency virus and is considered a critically important antimicrobial by the World Health Organization.,[3] [4] Resistance against aminoglycoside antibiotics, such as ribostamycin, is a growing concern. The resistant bacteria contain enzymes that modify the structure through phosphorylation, adenylation, and acetylation and prevent the antibiotic from being able to interact with the bacterial ribosomal RNAs.[5]
The biosynthesis of ribostamycin begins with the sugar D-glucose, which is phosphorylated at the 6 position to form glucose-6-phosphate. The enzyme rbmA contains a genetic sequence that corresponds to NAD+ binding and catalyzes the formation of 2-deoxy-scyllo-inosose. The enzyme rmbB then catalyzes the transamination of 2-deoxy-scyllo-inosose to 2-deoxy-scyllo-inosamine with L-glutamine and pyridoxal phosphate (PLP). Enzyme rbmC oxidizes the ring to 2-deoxy-3-amino-scyllo-inosose, which is then transaminated by enzyme rmbB to DOS. DOS is then glycosylated by the glycosyltransferase rmbD with uridine diphosphate N-acetylglucosamine (UDP-Glc-NAc) to form 2’-N-acetylparomamine. The deacetylase removes the acetyl group and forms paromamine. Paromamine is oxidized by enzyme rbmG and then enzyme rmbH transaminates to produce neamine. Neamine is then ribosylated to form ribostamycin.