Figure 5. XaxAB heterodimer interactions in the pore complex.

(a) Overview of interaction interfaces between XaxA and XaxB. (b–c) Network of putative hydrogen bonds between the tail domains. (d) Putative salt bridges in the junction connecting the neck and head domains. (e) The hydrophobic head domains of XaxA and XaxB are stabilized by a cluster of aromatic amino acids. (f) Hydrophobic interface between the transmembrane domain of XaxA and XaxB in one subunit of the pore. Left: XaxB is depicted in ribbon and XaxA in surface representation colored by hydrophobicity. Right: XaxA is depicted in ribbon representation and XaxB in surface representation colored by hydrophobicity. Protomers of XaxA and XaxB are depicted in green and yellow, respectively. Helices not involved in the interaction are shown in a lighter color for visualization purposes.