Extended Data Figure 8. Sequence alignment of KdpA from a diverse group of bacteria.

Selection of the sequences was done with the divblast server⁴⁹ and alignment using clustal omega⁴⁸. Secondary structure corresponds to that observed for KdpA (Fig. 1). Pink stars indicate residues reported by Buurman et al.⁵ and pink diamonds indicate residues reported by Dorus et al.⁶ to increase the apparent K_d for K⁺ to 0.3 mM or higher. Red triangles indicate residues implicated in coupling with KdpB, namely the Glu370 and Arg393 at the cytoplasmic end of the selectivity filter (Fig. 2c) and Arg400 that forms a salt bridge to the P-domain of KdpB (Fig. 3b). Blue triangles indicate residues forming H-bonds to the periplasmic domain of KdpC.