Octaketide chain

Abe I, Oguro S, Utsumi Y, Sano Y, Noguchi H (2005) Engineered biosynthesis of plant polyketides chain length control in an octaketide-producing plant Type III polyketide synthase. J Am Chem Soc 127 12709-12716... 

MAT has stringent specificity toward malonyl-CoA, which is reflected in the exclusive utilization of malonyl extender units by Type n PKS 7 Together, these four enzymes consist of the smallest set of enzymes required for the synthesis of a complete polyketide chain. For example, the minimal PKS from the actinorhodin (act) biosynthetic pathway synthesizes an octaketide (Cjg) backbone from eight malonyl-CoA equivalents, the tetracenomycin (tan) minimal PKS synthesizes a decaketide (C20) backbone from ten equivalents of malonyl-CoA (Figure 8A), and the pradimycin (pms) minimal PKS synthesizes a dodecaketide (C24) backbone from twelve equivalents of malonyl-CoA. ... 

The Cj symmetrical macrodiolide elaiophylin (41) consists of two identical polyketide chains which are linked to a deoxyfucose at C-13 [83]. Here, it was assumed that macrodilactone formation is the last biosynthetic step, and only one glycosyl transfer step is necessary prior to lactonization. However, incorporation experiments with the complete (glycosylated) octaketide half 42 failed. Later, after changing the fermentation parameters, the asymmetrical mono-glycosyl derivative 43 was isolated, indicating that the two glycosyl transfer steps take place after generation of the macrodiolide 44 [83-85] (Scheme 16). 

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