Biosynthesis of aromatic polyketides

Aromatic polyketides differ from other polyketides by their characteristic polycyclic aromatic structures. These polyketides are widely distributed in bacteria, fungi, and plants, and many of them are clinically valuable agen ts or exhibit other fascinating biological activities. Analogous to fatty a cids and reduced polyketide biosynthesis, aromatic polyketide biosynthesis is accomplished by the polyketide synthases that catalyze sequential decarb oxylative condensation between the starter and extender units to yield a li near poly-beta-ketone intermediate. The latter undergoes regiospecific redu ction, aromatization, or cyclization to furnish the polycyclic aromatic str uctures, which are further modified by tailoring enzymes to imbue them with various biological activities. This review begins with a brief discussion on the architectural organizations among Various polyketide synthase genes and genetic contributions to understanding polyketide synthases. It then pr esents a comprehensive account of the most recent advances in the biochemis try and enzymology of bacterial, fungal, and plant polyketide synthases, wi th emphasis on in vitro studies. It concludes with a cautious summary of th e so-called design-rules to guide rational engineering of polyketide syntha ses for the synthesis of novel aromatic polyketides.