Overall topology of . (A) Ribbon representation of the asymmetric unit. CheX is cyan and CheY3 is green. CheY3 Asp79 (orange), (purple), CheX Glu96 (red, Upper), and CheX Asn99 (red, Lower) are in stick representation. Mg2+ is a magenta sphere. (B).Overlay of B. burgdorferi CheX (cyan) and T. maritima CheX chain B (pdb 1XKO, tan). Regions of B. burgdorferi CheX with high disorder (Cα thermal B-factors > 70) are blue. B. burgdorferi CheX residues 37–40 are sketched as blue dots. T. maritima CheX residues corresponding to the disordered regions of B. burgdorferi CheX are red.