title: Biosynthesis of a novel 3-oxo-2-tetradecyloctadecanoate-containing phospholipid by a cell-free extract of Corynebacterium diphtheriae.
abstract: We have isolated, purified, and identified by chemical analyses and mass spectrometry, a novel 3-oxo-2-tetradecyloctadecanoate (dehydrocorynomycolate)-containing phospholipid (PL-1) from the chloroform-methanol extract of Corynebacterium diphtheriae. This phospholipid was separated from all of the other known dehydrocorynomycolate and 3-hydroxy-2-tetradecyloctadecanoate (corynomycolate)-containing lipids and found to be unstable even at -20 degrees C. It was present in trace amounts as a homologous series (molecular weights of 1400 and 1404 as the methyl esters) and composed of a dehydrocorynomycolate, a phosphate group, a diacylglycerol, and an unidentified amine-containing component. Because of the complexity of these phospholipids, their complete structural determination is yet to be completed. A cell-free extract of C. diphtheriae catalyzed the incorporation of radiolabel from [14C]palmitic acid into PL-1. This incorporation was ATP-dependent, and the rate was linear with respect to both time and protein concentration. The radiolabel was incorporated primarily into the dehydrocorynomycoloyl moiety of PL-1. While avidin did not show any significant effect, cerulenin showed a marked inhibition of this reaction. Based on these results, we suggest that this dehydrocorynomycolate-containing PL-1 may be the long-sought acyl carrier-containing product of a Claisen-type condensation.
authors.affiliation: Mycobacteriology Research Laboratory, William S. Middleton Memorial Veterans Hospital, Madison, WI 53705.
authors.forename: A K
authors.initials: AK
authors.lastname: Datta
authors.forename: K
authors.initials: K
authors.lastname: Takayama
mesh_terms: D001360:Avidin; D002250:Carbon Radioisotopes; D002474:Cell-Free System; D002569:Cerulenin; D003353:Corynebacterium diphtheriae / Q000378:metabolism*; D009171:Mycolic Acids / Q000032:analysis*; D010168:Palmitates / Q000032:analysis; D010743:Phospholipids / Q000096:biosynthesis* / Q000737:chemistry / Q000302:isolation & purification; D013228:Stearates / Q000032:analysis*
chemical_list: D002250:Carbon Radioisotopes; D009171:Mycolic Acids; D010168:Palmitates; D010743:Phospholipids; D013228:Stearates; D001360:Avidin; D002569:Cerulenin; C082548:3-oxo-2-tetradecyloctadecanoic acid