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J. Microbiol. Biotechnol. 2007; 17(5): 830-839

Published online May 28, 2007

Copyright © The Korean Society for Microbiology and Biotechnology.

Cloning, Sequencing, and Characterization of the Pradimicin Biosynthetic Gene Cluster of Actinomadura hibisca P157-2

Kim, Byung Chul , Jung Min Lee , Jong Seog Ahn 1 and Beom Seok Kim 1*

Division of Biotechnology, College of Life Sciences & Biotechnology, Korea University, Seoul 136-713, Korea, 1Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-806, Korea

Abstract

Pradimicins are potent antifungal antibiotics having an unusual dihydrobenzo[$\alpha$]naphthacenequinone aglycone substituted with D-alanine and sugars. Pradimicins are polyketide antibiotics produced by Actinomadura hibisca P157-2. The gene cluster involved in the biosynthesis of pradimicins was cloned and sequenced. The pradimicin gene cluster was localized to a 39-kb DNA segment and its involvement in the biosynthesis of pradimicin was proven by gene inactivation of prmA and prmB(ketosynthases $\alpha\;and\;\beta$). The pradimicin gene cluster consists of 28 open reading frames(ORFs), encoding a type II polyketide synthase(PKS), the enzymes involved in sugar biosynthesis and tailoring enzymes as well as two resistance proteins. The deduced proteins showed strong similarities to the previously validated gene clusters of angucyclic polyketides such as rubromycin, griseorhodin, and fredericamycin. From the pradimicin gene cluster, prmP3 encoding a component of the acetyl-CoA carboxylase complex was disrupted. The production levels of pradimicins of the resulting mutants decreased to 62% of the level produced by the wild-type strain, which indicate that the acetyl-CoA carboxylase gene would have a significant role in the production of pradimicins through supplying the extender unit precursor, malonyl-CoA.

Keywords: Actinomadura hibisca, pradimicin, type II polyketide synthase, polyketide biosynthesis