Biosynthesis of antibiotic 1233A (F-244) and preparation of [14C]1233A.

The biosynthesis of antibiotic 1233A (F-244) was studied by feeding 13C-labeled precursors to the producing organism, Scopulariopsis sp. F-244. 13C NMR spectroscopy established that 1233A is derived from 4 methionines and 7 acetates. Seven acetates are condensed to form a hexaketide and 4 methyl residues from methionine are introduced into the main skeleton. The beta-lactone is derived from the alpha-carboxylic acid of the hexaketide. Since methionine was efficiently incorporated into 1233A, radiolabeled 1233A was prepared biosynthetically by feeding [14C]methionine to the producer. As a result, [14C]1233A was obtained with high specific radioactivity (27.2 muCi/mumols).