Fig. 5.

Binding mode of SspB₂ to ZBD trimer of dimers. (A–D) Shown are the different possible modes of binding between two C-terminal tails of SspB₂ and the ZBD trimer of dimers shown in surface representation. ZBD residues implicated in interacting with SspB C terminus by NMR and mutagenesis are in a darker color. The AAA⁺ ring of ClpX is assumed to be below the ZBD trimer of dimers. Arrowheads represent the N termini of the tails of SspB₂ and point toward the rest of SspB₂ body, whereas the slashes represent the C termini of the tails. Tails in dashes and in solid colors are below and above the plane of the ZBD oligomer, respectively. The three ZBD dimers might be in a more open and less planar configuration than shown.