Figure 77.

Lattice reconfiguration behavior of disulfide-linked RhuA crystals. a) Dynamic, auxetic nature of ^C98RhuA crystals. From top: reconstructed 2D images of seven distinct conformational states of the 2D crystals (I-VII); Magnified views of states II, V and VII; structural models of conformations II, V and VII with unit cells and hinge angles (α) between RhuA molecules highlighted in black and red. b) Surface representation (top) of a ^CEERhuA tetramer with residues 98 and 57/66 colored in black and red, respectively. Illustration of ^CEERhuA lattice dynamics (middle) and ns-TEM images of lattices (bottom) with open and equilibrium states for ^CEERhuA and closed state for ^C98RhuA. c) Free-energy and solvent entropy profiles for ^CEERhuA (red and black lines) and ^C98RhuA (faint blue and grey lines). d) Chemical and mechanical reconfiguration behavior of ^CEERhuA lattices. e) While ^C98RhuA crystals exhibit only one mechanical reconfiguration mode, ^CEERhuA crystals have two modes of mechanical switching and an additional purely Ca²⁺-induced, chemical switching mode. (a) Adapted with permission from Ref.²²⁵. Copyright 2016 NPG. (b-e) Adapted with permission from Ref.²²⁶. Copyright 2018 NPG.