Fig. 7.

Residue rearrangement and potential substrate-binding cavity along the translocation pathway. (A) Movement of TM3 and TM4 of the MetI subunits form a small cavity (shown in Fig. 5A), whose boundary is defined by residues Y160 and F103 along the translocation pathway. (B) Superposition of MetI subunits in the OWF and IWF conformation reveals a rearrangement of a potential selectivity filter, M-Ω-Ω-M (Ω, aromatic ring residues), along the translocation pathway of the OWF MetNIQ. Side chains in the OWF and IWF conformations are colored cyan and black, respectively.