Fig. 7.

Distances between the Cα atoms of diagnostic, inter-helical cysteine pairs in chemoreceptor Trg as a function of ligand-induced conformational changes. Distances between Cα atoms of cysteine pairs in the model of the Trg periplasmic plus cytoplasmic domains were calculated at incremental steps of two ligand-induced conformational changes. (A) Transmembrane helix 1 (TM1)–transmembrane helix 2 (TM2) disulfides between the indicated positions over the course of sliding displacements of TM2 along its long axis. Ligand occupancy increased the rates of formation for two disulfides (incr) and decreased the rates for the other two (decr). (B) TM1-TM2 disulfides between the indicated positions over the course of rotation of one subunit from one to another orientation in the crystal structures of the periplasmic domain. (C) TM1-TM1` disulfides between the indicated positions over the course of sliding displacements of TM2 along its long axis. (D) TM1-TM1` disulfides between the indicated positions over the course of rotation of one subunit from one to another orientation in the crystal structures of the periplasmic domain. Labels as in Figure 5B ▶.