Structures of the mycobacterial membrane protein MmpL3 reveal its mechanism of lipid transport
Fig 2
Structures of MmpL3-TMM I and MmpL3-TMM II.
(a) Side view of the surface representation of MmpL3-TMM I. The narrowest region of the channel created by the MmpL3 membrane protein, measured between the Cα atoms of residues S423 and N524 (red triangles), is 10.5 Å. (b) Side view of the surface representation of MmpL3-GDN. The narrowest region of the channel created by the MmpL3 membrane protein, measured between the Cα atoms of residues S423 and N524 (red triangles), is 12.0 Å. (c) Ribbon diagram of MmpL3-TMM I viewed in the membrane plane. (d) Ribbon diagram of MmpL3-TMM II viewed in the membrane plane. (e) Superimposition of the structures of MmpL3-TMM I and MmpL3-TMM II. This superimposition suggests that there is a drastic change in conformation of the transmembrane helices, including TMs 7 and 10, in addition to the rigid body movement of subdomain PD2. MmpL3, mycobacterial membrane protein large 3; MmpL3-GDN, MmpL3-glycol-diosgenin; MmpL3-TMM, MmpL3-trehalose monomycolate; TM, transmembrane.