Biosynthetic studies on the antibiotics PF1140: a novel pathway for a 2-pyridone framework

Incorporation of labeled acetate and l-serine into PF1140 in Eupenicillium sp. indicated that the skeleton of PF1140 is derived from five acetates and a l-serine. Upon administration of [1,3-13C2]glycerol, a precursor of biotransformation into l-[1,3-13C2]serine, the isotopic labels became contiguous in the resultant 2-pyridone of PF1140. Based on the feeding experiments, a novel and potentially general biosynthetic pathway for a 2-pyridone framework has been proposed, in which an acyl tetramic acid precursor could be converted via a ring expansion with loss of the hydroxyl group.