title: Epimerization at C-3'' in butirosin biosynthesis by an NAD(+) -dependent dehydrogenase BtrE and an NADPH-dependent reductase BtrF.
abstract: Butirosin is an aminoglycoside antibiotic consisting two epimers at C-3'' of ribostamycin/xylostasin with a unique 4-amino-2-hydroxybutyrate moiety at C-1 of the aminocyclitol 2-deoxystreptamine (2DOS). To date, most of the enzymes encoded in the biosynthetic gene cluster for butirosin, from the producing strain Bacillus circulans, have been characterized. A few unknown functional proteins, including nicotinamide adenine dinucleotide cofactor-dependent dehydrogenase/reductase (BtrE and BtrF), are supposed to be involved in the epimerization at C-3'' of butirosin B/ribostamycin but remain to be characterized. Herein, the conversion of ribostamycin to xylsostasin by BtrE and BtrF in the presence of NAD(+) and NADPH was demonstrated. BtrE oxidized the C-3'' of ribostamycin with NAD(+) to yield 3''-oxoribostamycin. BtrF then reduced the generated 3''-oxoribostamycin with NADPH to produce xylostasin. This reaction step was the last piece of butirosin biosynthesis to be described.
authors.affiliation: Department of Chemistry, Tokyo Institute of Technology, Okayama, Meguro-ku, Tokyo 152-8551 (Japan).
authors.forename: Ryohei
authors.initials: R
authors.lastname: Takeishi
authors.forename: Fumitaka
authors.initials: F
authors.lastname: Kudo
authors.forename: Mario
authors.initials: M
authors.lastname: Numakura
authors.forename: Tadashi
authors.initials: T
authors.lastname: Eguchi
mesh_terms: D000429:Alcohol Oxidoreductases / Q000737:chemistry / Q000378:metabolism*; D001407:Bacillus / Q000201:enzymology / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D002076:Butirosin Sulfate / Q000096:biosynthesis* / Q000737:chemistry*; D015394:Molecular Structure; D009243:NAD / Q000378:metabolism; D009249:NADP / Q000378:metabolism; D010088:Oxidoreductases / Q000737:chemistry / Q000378:metabolism*; D012271:Ribostamycin / Q000031:analogs & derivatives / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D009243:NAD; D012271:Ribostamycin; D002076:Butirosin Sulfate; D009249:NADP; D010088:Oxidoreductases; D000429:Alcohol Oxidoreductases
keywords: aminoglycosides; biosynthesis; butirosin; epimerization; natural products; ribostamycin