Isolation of C 55 -isoprenylpyrophosphate from micrococcus lysodeikticus.

The peptidoglycan of bacterial cell walls is biosynthesized in a complex reaction cycle in which lipid intermediates serve as carriers of activated sugar fragments (1). The lipid intermediates (e.g., lipid-P-P-disaccharide-pentapeptide) have been identified as derivatives of an acyclic isoprenoid alcohol which has a chain length of 11 isoprene units (2, 3). In the cyclic reaction, the disaccharide-pentapeptide moiety of the lipid intermediate is transferred to an acceptor with the liberation of lipid pyrophosphate. The latter is then rapidly dephosphorylated to regenerate lipid phosphate, the lipid component which is required to initiate the cycle. The steady state concentration of lipid pyrophosphate in the various organisms which have been examined so far is exceedingly low, and its occurrence as an intermediate in the reaction cycle was shown only after inhibition of the cycle with bacitracin (4). This antibiotic inhibits the dephosphorylation of lipid pyrophosphate which therefore accumulates. The lipid pyrophosphate intermediate has previously been obtained in relatively small amounts by inhibiting cell-free enzyme preparations which would otherwise be capable of converting radioactive UDP-N-acetylmuramylpentapeptide to peptidoglycan (4). In the present paper, a large scale isolation of lipid pyrophosphate has been carried out, making use of its accumulation in intact cells of bacteria inhibited by bacitracin.