FEATURES

DESCRIPTION

Also known as PIKA4_STRVZ, pikAIV. Involved in the biosynthesis of 12- and 14-membered ring macrolactone antibiotics such as methymycin and neomethymycin, and pikromycin and narbomycin, respectively. Component of the pikromycin PKS which catalyzes the biosynthesis of both precursors 10-deoxymethynolide (12-membered ring macrolactone) and narbonolide (14-membered ring macrolactone). Chain elongation through PikAI, PikAII and PikAIII followed by thioesterase catalyzed termination results in the production of 10-deoxymethynolide, while continued elongation through PikAIV, followed by thioesterase (TE) catalyzed cyclization results in the biosynthesis of the narbonolide. The thioesterase can use a series of diketide-N-acetylcysteamine (SNAC) thioesters, but has a strong preference for the 2-methyl-3-ketopentanoyl-SNAC over the stereoisomers of 2-methyl-3-hydroxyacyl-SNAC (PubMed:12379101, PubMed:12733905). Homodimer (PubMed:12379102, PubMed:16969373, PubMed:16969372, PubMed:19146481). Pikromycin PKS consists of a combination of multimodular (PikAI and PikAII) and monomodular (PikAIII and PikAIV) polypeptides each coding for a functional synthase subunit which participates in 1 (monomodular) or 2 (multimodular) of the six FAS-like elongation steps required for formation of the polyketide. Module 1, 2, 3, 4, 5, and 6 participating in biosynthesis steps 1, 2, 3, 4, 5, and 6, respectively.

EXTERNAL LINKS

pikAIV

Narbonolide/10-deoxymethynolide synthase PikA4, module 6

pikAIV

Molecular Synopsis