New Insights into the Mycolate-Containing Compound Biosynthesis and Transport in Mycobacteria.

Mycolic acids are extremely-long-chain fatty acids that compose a large family of mycolate-containing compounds, major envelope lipid components and critical pathogenicity factors of Mycobacterium tuberculosis. In recent years there have been major advances in understanding their metabolic pathway. Unknown enzymes of the fatty acid synthase type II elongation system and the condensation system that builds the mycolic acid scaffold were identified. Missing links with the mycolate-containing compound biosynthesis-such as the mechanisms of transfer onto trehalose and of translocation through the inner membrane-were deciphered, while recycling processes have emerged. Beyond the more accurate picture of the biosynthesis and translocation pathways dedicated to these unique molecules, major issues that should be addressed in the future are also discussed.