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. 2009 Apr 3;106(16):6644–6649. doi: 10.1073/pnas.0810663106

Fig. 1.

Fig. 1.

Crystal structure of FL KcsA in complex with Fab2. (A) CDR sequences of the 3 Fabs selected against FL KcsA from a “reduced genetic code” phage display library. Numbering is according to the Kabat definition (36). Gly is green; Tyr, yellow, Ser, red; and nondiversified positions, gray. (B) Crystal packing of the KcsA–Fab2 complex at 3.8 Å. KcsA is in orange, and the light and heavy chains of the Fab are in cyan (light chain) and magenta (heavy chain). (C) Simulated annealing composite-omit 2Fo-Fc map (contoured at 1σ) of FL KcsA. The red trace shows the fitted model as Cα tracing. (D) The final model of the KcsA–Fab complex. Three regions distinguished by the level of symmetry are highlighted: the fourfold TM segments (blue color; residues 22–117), the twofold bulge helix (red color; residues 118–135), and the fourfold distal C-terminal bundle (gray color; residues 136–158). (E and F) Experimental (E) EPR mobility and (F) NiEdda accessibility parameters (11) from membrane-reconstituted FL KcsA, mapped on the crystal model of FL KcsA. The scales represent a linear increase in local dynamics (E) and accessibility to the aqueous media (F).