Structure-based design of LC1 Mutants. The mean LC1 ribbon structure (Protein Data Bank accession no. 1M9L; left) and three views of the van der Waals molecular surface (right) are shown. The LRR region forms two β sheets and a helical face. The larger β sheet face (left, magenta) contains a single hydrophobic patch (green) centered on W99 that is predicted to bind the γ HC. The C-terminal portion of LC1 consists of a helical region, the orientation of which is controlled by two residues (M182 [yellow] and D185 [blue]) that show high backbone dynamics. The terminal α9 helix likely protrudes into the AAA⁺ domain and contains two Arg residues (R189 and R196; pink) that potentially make ionic contacts with the motor domain and/or nucleotide.