INHIBITION OF MYCOLIC ACID BIOSYNTHESIS IN A CELL-WALL PREPARATION FROM MYCOBACTERIUM-SMEGMATIS BY METHYL 4-(2-OCTADECYLCYLOPROPEN-1-YL) BUTANOATE, A STRUCTURAL ANALOG OF A KEY PRECURSOR

[C-14]acetate was incorporated into mycolic acids by a cell-free, cell -wall fraction from Mycobacterium smegmatis. This activity was inhibit ed by methyl 4-(2-octadecylcyclopropen-1-yl) butanoate which was desig ned as a structural analogue of cis-tetracos-5-enoate, a precursor of mycolic acid biosynthesis. Other fatty acids and their methyl esters f ailed to inhibit mycolic acid biosynthesis at the concentration 1-2 mg ml-1, at which methyl 4-(2-octadecylcyclopropen-1-yl) butanoate was e ffective. Thus a novel agent was shown to act against an enzyme activi ty or target involved specifically in biosynthesis of a characteristic , mycobacterial, cell-wall component.