(A) Schematic representation of the AVR-PikD/Pikp-HMA(monomer), highlighting interfacing residues. The effector is shown in green cartoon, with side chains as sticks and green carbon atoms (no surface). The Pikp-HMA is shown in blue cartoon, with side chains as sticks and blue carbon atoms; the molecular surface of this protein is also depicted. Effector residues selected for mutation are labelled, as are important interface residues of Pikp-HMA discussed in the text. Hydrogen bonds/salt-bridges are shown as dashed lines and the di-sulphide bond as yellow bars. (B) Buried surface areas of AVR-PikD (left, purple) and Pikp-HMA (right, brown) separated and shown from the perspective of the partner molecule. Cartoon and amino acid side chains shown are as for panel (A). (C) Comparison of the Pikp-HMA (monomer, blue) with yeast Ccc2A (wheat) showing the conservation of the HMA fold. The copper ion bound to Ccc2a is shown as a red sphere. (D) Comparison of AVR-PikD (green) and AVR-Piz-t (pink) structures showing the conservation of the β-sandwich structure, and the N-terminal extension of AVR-PikD.