alpha,alpha'-Trehalose-6,6'-bismycolate

Trehalose 6,6' dimycolate (TDM) or cord factor, is a glycolipid molecule found in the cell wall of Mycobacterium tuberculosis and similar species. It is the primary lipid found on the exterior of M. tuberculosis cells. Cord factor influences the arrangement of M. tuberculosis cells into long and slender formations in the ability of Mycobacterium tuberculosis to persist in such lesions without producing inflammation. TDM is unique in that it has three distinct sets of biologic activities depending on its physical conformation. As a single molecule, TDM stimulates macrophage C-type lectin receptors including Mincle. TDM can also form three crystal like structures, cylindrical micelles, intercalated bilayer and monolayer, that have distinct non receptor driven activities that depend on modulation of interactions with water. In the monolayer form, TDM is highly toxic and destroys cells in minutes upon contact. Mycobacterium tuberculosis antigen 85 mycolyl transferases catalyze transfer of the fatty acid mycolate from one trehalose monomycolate to another, resulting in trehalose dimycolate and free trehalose, thus helping to build the bacterial cell wall.