FIG. 5.

Discrete conformational states in the functional pathways of Spo0F and CheY. (a) Conformational fluctuations of Spo0F in the phosphotransfer pathway visualized in terms of closed and open states. (I) Unphosphorylated state; (II) Spo0F interacting with KinA-P; (III) phosphorylated state; (IV) Spo0F-P interacting with Spo0B. (b) The two conformational states of CheY. (Top) The external orientation of Y106 favors interaction with P2 domain; (bottom) the internal orientation of Y106 paves the way for FliM to associate with CheY. The phosphoryl moiety and the repositioned residues are shown in red.