Functional Analyses of Oxygenases in Jadomycin Biosynthesis and Identification of JadH as a Bifunctional Oxygenase/Dehydrase

Abstract

A novel angucycline metabolite, 2,3-dehydro-UWM6, was identified in a jadH mutant of Streptomyces venezuelae ISP5230. Both UWM6 and 2,3-dehydro-UWM6 could be converted to jadomycin A or B by a ketosynthase ␣ (jadA) mutant of S. venezuelae. These angucycline intermediates were also converted to jadomycin A by transformant of the heterologous host Streptomyces lividans expressing the jadFGH oxygenases in vivo and by its cell-free extracts in vitro; thus the three gene products JadFGH are implicated in catalysis of the postpolyketide synthase biosynthetic reactions converting UWM6 to jadomycin aglycone. Genetic and biochemical analyses indicate that JadH possesses dehydrase activity, not previously associated with polyketide-modifying oxygenase. Since the formation of aromatic polyketides often requires multiple dehydration steps, bifunctionality of oxygenases modifying aromatic polyketides may be a general phenomenon.

Evaluation of the cytotoxic activity of new jadomycin derivatives reveals the potential to improve its selectivity against tumor cells

“…Three oxygenases, JadF, JadG and JadH, have been implicated in the ring cleavage and amino-acid insertion process. [10][11][12][13] JadH was shown to be a FAD-dependent bifunctional hydroxylase/dehydrase in vitro, 10,14 catalyzing C-12 monooxygenation and 4a,12b-dehydration of 2,3-dehydro-UWM6, whereas the functions of JadF and JadG are still not clear.…”

Cloning and Characterization of a Gene Cluster for Hatomarubigin Biosynthesis in Streptomyces sp. Strain 2238-SVT4

“…5). PCR primers were designed from the conserved amino acid sequences of the aromatase (lanL, jadD, and urdL) and cyclase (lanF, jadI, and urdF) genes in the landomycin producer S. cyanogenus S136 (19), the jadomycin producer S. venezuelae ISP5230 (3,7), and the urdamycin producer S. fradiae Tü2717 (4,6). PCR amplification of Streptomyces sp.…”

Über das Acceptorsubstrat der C‐Glycosyltransferase UrdGT2: drei Prejadomycin‐C‐glycoside aus einer konstruierten Mutante von Streptomyces globisporus 1912 ΔlndE(urdGT2)

“…Der Befund, dass eine Verbindung ohne 3-OH-Gruppe, nämlich 6, früher in der Landomycin-Biosynthese auftreten soll als zwei Verbindungen mit 3-OH-Gruppen, nämlich 11 und 12, erscheint widersprüchlich. In Versuchen mit der überexprimierten Oxygenase JadH, die im Jadomycin-Weg die 12-Oxygenierung bewirkt, [25,26] wurde Prejadomycin (6) jedoch teilweise direkt in Rabelomycin (12) umgewandelt, was nur durch eine Umlagerung zu erklären ist, die mit einer Michael-Addition der 4a-OH-Gruppe an 3-Position beginnt. [31] Eine solche Umlagerung wurde schon von Hutchinson et al beobachtet, aber nicht erklärt.…”