Required for the import of both fatty acids and cholesterol during growth in macrophages and in axenic culture. Facilitates the uptake of these lipids by stabilizing protein subunits of the Mce1 and Mce4 multi-subunit transporters, which transport fatty acids and cholesterol, respectively. Required for full virulence in vivo. Interacts with the Mce1 and Mce4 accessory subunits Rv0199/OmamA, Rv0177/Mam1C and Rv3492c/Mam4B. Mutant is unable to utilize both fatty acids and cholesterol during infection in macrophages.