Mupirocin - Wikipedia, the free encyclopedia9-[(E)-4-[(2S,3R,4R,5S)-3,4-dihydroxy-5-[[(2S,3S)-3- [(2S,3S)-3-hydroxybutan-2-yl]oxiran-2-yl]methyl] oxan-2-yl]-3-methylbut-2-enoyl]oxynonanoic acid Mupirocin is a mixture of several pseudomonic acids, with pseudomonic acid A (PA-A) constituting greater than 90% of the mixture. Also present in mupirocin are pseudomonic acid B with an additional hydroxyl group at C8, One of the AT domains from MmpC may transfer an activated acetyl group from acetyl-Coenzyme A (CoA) to the first ACP domain. The chain is extended by malonyl-CoA, followed by a SAM-dependent methylation at C12 (see Figure 1 for PA-A numbering) and reduction of the B-keto group to an alcohol. The dehydration (DH) domain in module 1 is predicted to be non-functional due to a mutation in the conserved active site region. Module 2 adds another two carbons by malonyl-CoA extender unit, followed by ketoreduction (KR) and dehydration. Module three adds a malonyl-CoA extender unit, followed by SAM-dependent methylation at C8, ketoreduction, and dehydration. Module 4 extends the molecule with a malonyl-CoA unit followed by ketoreduction.
