title: The mycinose-biosynthetic genes of Streptomyces fradiae, producer of tylosin.
abstract: The tylE-J region of the tylosin-biosynthetic gene cluster of Streptomyces fradiae contains six open reading frames. The products of tylJ and tylD are nucleoside diphospho (NDP)-deoxyhexose 3-epimerase and NDP-deoxyhexose 4-ketoreductase, respectively, involved in the synthesis of NDP-6-deoxyallose from NDP-4-keto, 6-deoxyglucose. After incorporation of deoxyallose at C23-OH of the polyketide lactone, tylosin biosynthesis is completed by the products of tylE and tylF, which convert the deoxyallosyl moiety to mycinose via bis-O-methylation at 2-OH and 3-OH, respectively. Hydroxylation of the polyketide lactone at C23 is catalysed by the cytochrome P450 enzyme, TylHl. The product of tylHll is a ferredoxin of unknown specificity that could conceivably act together with TylHl.
authors.affiliation: Department of Biochemistry, University of Leicester, Leicester LE1 7RH, UK.
authors.initials: N
authors.lastname: Bate
authors.initials: E
authors.lastname: Cundliffe