Nonprotein Structures from Mycobacteria: Emerging Actors for Tuberculosis Control

Figure 1

Proposed ultrastructural array of M. tuberculosis cell wall. Cell wall includes a great variety of lipids (depicted in brown, with polar functional groups in blue) and sugars (schematized by hexagons and pentagons in different colors). Surrounding the plasma membrane, cell-wall peptidoglycan is attached to another polysaccharide, the arabinogalactan. Long-chain fatty acids, the mycolic acids, are attached to arabinogalactan through ester linkages. An outer lipid bilayer called mycomembrane is formed by mycolic acids and free amphipathic lipids. Finally, some strains display free saccharides, such as glucan, at the outermost layer. GMM, glucose monomycolate; PIM, phosphatidylinositol mannoside; SL, sulfatide; TDM, trehalose dimycolate or cord factor. Cell-wall proteins are depicted in arbitrary positions. Figure is out of scale.