Structures of the <i>M</i>. <i>smegmatis</i> MmpL3 transporter.

(a) Side view of the surface representation of MmpL3-ND. 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 8.6 Å. (b) Ribbon diagram of MmpL3-ND viewed in the membrane plane. (c) 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 11.5 Å. (d) Ribbon diagram of MmpL3-GDN viewed in the membrane plane. (e) Superimposition of the structures of MmpL3-ND and MmpL3-GDN. This superimposition suggests that the major difference between these 2 structures is the location of PD2, which rotates by approximately 6° in a rigid body fashion (red arrow) when compared the MmpL3-GDN structure to that of MmpL3-ND. MmpL3, mycobacterial membrane protein large 3; MmpL3-GDN, MmpL3-glycol-diosgenin; MmpL3-ND, MmpL3-nanodisc.