MDP1 binds to the cell wall of BCG. (A to C) BCG was incubated with FLUOS-labeled MDP1 (A), egg white lysozyme (B), and bovine histone H1 (C). Bacteria were viewed with a confocal scanning laser microscope. (D) ELISA to detect MDP1-lipid or -glycolipid interactions. Mycolic acids (bar b, alpha-MAME; bar c, methoxy-MAME; bar d, keto-MAME) and glycolipids (bar e, TMM; bar f, TDM) were immobilized on an ELISA plate and reacted with MDP1, and the level of binding was detected with anti-MDP1 MAb 3A. Bar a shows the results for a negative control without immobilization of either lipids or glycolipids. OD492, optical density at 492 nm. (E) Immunoprecipitation assay to detect physiological interaction of MDP1 and glycolipid. Cell wall derived from BCG was incubated with anti-MDP1 MAb 3A or control mouse IgG in the presence of protein G-coated Sepharose. Samples were spotted on a TLC plate and developed with the chloroform-methanol-acetone-acetic acid (80:20:6:1, vol/vol/vol/vol) solvent system.