title: Elucidation of post-PKS tailoring steps involved in landomycin biosynthesis.
abstract: The functional roles of all proposed enzymes involved in the post-PKS redox reactions of the biosynthesis of various landomycin aglycones were thoroughly studied, both in vivo and in vitro. The results revealed that LanM2 acts as a dehydratase and is responsible for concomitant release of the last PKS-tethered intermediate to yield prejadomycin (10). Prejadomycin (10) was confirmed to be a general pathway intermediate of the biosynthesis. Oxygenase LanE and the reductase LanV are sufficient to convert 10 into 11-deoxylandomycinone (5) in the presence of NADH. LanZ4 is a reductase providing reduced flavin (FMNH) co-factor to the partner enzyme LanZ5, which controls all remaining steps. LanZ5, a bifunctional oxygenase-dehydratase, is a key enzyme directing landomycin biosynthesis. It catalyzes hydroxylation at the 11-position preferentially only after the first glycosylation step, and requires the presence of LanZ4. In the absence of such a glycosylation, LanZ5 catalyzes C5,6-dehydration, leading to the production of anhydrolandomycinone (8) or tetrangulol (9). The overall results provided a revised pathway for the biosynthesis of the four aglycones that are found in various congeners of the landomycin group.
authors.affiliation: Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, 789 South Limestone Street, Lexington, KY 40536-0596, USA.
authors.forename: Madan K
authors.initials: MK
authors.lastname: Kharel
authors.forename: Pallab
authors.initials: P
authors.lastname: Pahari
authors.forename: Khaled A
authors.initials: KA
authors.lastname: Shaaban
authors.forename: Guojun
authors.initials: G
authors.lastname: Wang
authors.forename: Caleb
authors.initials: C
authors.lastname: Morris
authors.forename: Jürgen
authors.initials: J
authors.lastname: Rohr
mesh_terms: D000617:Aminoglycosides / Q000096:biosynthesis*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001551:Benz(a)Anthracenes / Q000378:metabolism; D003001:Cloning, Molecular; D004926:Escherichia coli; D006836:Hydro-Lyases / Q000235:genetics / Q000378:metabolism; D007546:Isoquinolines / Q000378:metabolism; D009243:NAD / Q000378:metabolism; D009285:Naphthoquinones / Q000378:metabolism; D009844:Oligosaccharides / Q000378:metabolism; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D010105:Oxygenases / Q000235:genetics / Q000378:metabolism; D048630:Polyketide Synthases / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013302:Streptomyces / Q000737:chemistry* / Q000201:enzymology / Q000235:genetics
chemical_list: D000617:Aminoglycosides; D001426:Bacterial Proteins; D001551:Benz(a)Anthracenes; D007546:Isoquinolines; D009285:Naphthoquinones; D009844:Oligosaccharides; D011994:Recombinant Proteins; C490012:anhydrolandomycinone; C113593:landomycin E; C493498:landomycin F; C520603:prejadomycin; D009243:NAD; C064648:landomycin A; C103670:tetrangulol; D048630:Polyketide Synthases; D010088:Oxidoreductases; D010105:Oxygenases; D006836:Hydro-Lyases