9cgn

Structural highlights

Function

PIKA4_STRVZ 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).^{[1] [2] [3] [4] [5] [6] [7]}

References

1. ↑ Tang L, Fu H, Betlach MC, McDaniel R. Elucidating the mechanism of chain termination switching in the picromycin/methymycin polyketide synthase. Chem Biol. 1999 Aug;6(8):553-8. doi: 10.1016/S1074-5521(99)80087-8. PMID:10421766 doi:http://dx.doi.org/10.1016/S1074-5521(99)80087-8
2. ↑ Xue Y, Sherman DH. Alternative modular polyketide synthase expression controls macrolactone structure. Nature. 2000 Feb 3;403(6769):571-5. PMID:10676969 doi:10.1038/35000624
3. ↑ Lu H, Tsai SC, Khosla C, Cane DE. Expression, site-directed mutagenesis, and steady state kinetic analysis of the terminal thioesterase domain of the methymycin/picromycin polyketide synthase. Biochemistry. 2002 Oct 22;41(42):12590-7. PMID:12379101 doi:10.1021/bi026006d
4. ↑ Yin Y, Lu H, Khosla C, Cane DE. Expression and kinetic analysis of the substrate specificity of modules 5 and 6 of the picromycin/methymycin polyketide synthase. J Am Chem Soc. 2003 May 14;125(19):5671-6. PMID:12733905 doi:10.1021/ja034574q
5. ↑ Akey DL, Kittendorf JD, Giraldes JW, Fecik RA, Sherman DH, Smith JL. Structural basis for macrolactonization by the pikromycin thioesterase. Nat Chem Biol. 2006 Oct;2(10):537-42. Epub 2006 Sep 10. PMID:16969372 doi:10.1038/nchembio824
6. ↑ Kittendorf JD, Beck BJ, Buchholz TJ, Seufert W, Sherman DH. Interrogating the molecular basis for multiple macrolactone ring formation by the pikromycin polyketide synthase. Chem Biol. 2007 Aug;14(8):944-54. PMID:17719493 doi:10.1016/j.chembiol.2007.07.013
7. ↑ Kittendorf JD, Sherman DH. The methymycin/pikromycin pathway: a model for metabolic diversity in natural product biosynthesis. Bioorg Med Chem. 2009 Mar 15;17(6):2137-46. doi: 10.1016/j.bmc.2008.10.082. Epub , 2008 Nov 5. PMID:19027305 doi:http://dx.doi.org/10.1016/j.bmc.2008.10.082