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. Author manuscript; available in PMC: 2011 May 11.
Published in final edited form as: Biochemistry. 2010 May 11;49(18):3824–3841. doi: 10.1021/bi100055m

FIGURE 9. Incorporation of the PDS ternary complex into an MCP membrane array.

FIGURE 9

(A) Spacing of the transmembrane MCP trimers observed by cryo-EM (70–78 Å) taken with the PDS structure suggest that the P3 domain could bridge adjacent receptor trimers. If PDS orientation A is superimposed on a single dimer within the trimer, the receptor from orientation B overlaps with the position and an adjacent dimer within the trimer. CheW and P5 domains associated with the same CheA subunit are also spaced appropriately to bridge adjacent trimers with similar interaction surfaces (red and yellow). In left view, no P4 domains are shown, in right view, only one. Receptor trimers were generated from the coordinates of the Tsr cytoplasmic domain (39), adjusted to fit EM reconstruction envelopes (57). (B) Schematic diagram for how edge positioning of the CheA P3 domain could be elaborated into a hexagonal lattice of chemoreceptors. Domain sizes and edge spacings are roughly to scale and thus, only alternating edges could accommodate a P3 domain and still allow the associated P5 and CheW domains to fit within a hexagon.