ID   2.3.1.290
DE   spectinabilin polyketide synthase system.
AN   spectinabilin polyketide synthase complex.
CA   6 (S)-methylmalonyl-CoA + 4-nitrobenzoyl-CoA + 12 H(+) + malonyl-CoA +
CA   6 NADPH = 7 CO2 + 8 CoA + demethyldeoxyspectinabilin + 5 H2O + 6 NADP(+).
CC   -!- This polyketide synthase, characterized from the bacteria
CC       Streptomyces orinoci and Streptomyces spectabilis, generates the
CC       backbone of the antibiotic spectinabilin.
CC   -!- It is composed of 6 modules that total 28 domains and is encoded by
CC       four genes.
CC   -!- The enzyme accepts the unusual starter unit 4-nitrobenzoyl-CoA and
CC       extends it by 6 molecules of (S)-methylmalonyl-CoA and a single
CC       molecule of malonyl-CoA.
CC   -!- The first module (encoded by norA) is used twice in an iterative
CC       fashion, so that the seven Claisen condensation reactions are
CC       catalyzed by only six modules.
CC   -!- The iteration becomes possible by the transfer of the [acp]-bound
CC       polyketide intermediate back to the ketosynthase (KS) domain on the
CC       opposite polyketide synthase strand (polyketides are homodimeric).
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