(A) Schematic representation of the structure of ancHMALVKIE complexed with the AVR-PikD effector. The molecules are shown as ribbons with selected side chains presented as sticks and labelled; the colours of the residue labels match the colours of the respective molecules. The molecular surfaces of AVR-PikD (pink) and LVKIE residues (blue) within ancHMALVKIE are also shown. Dashed lines represent hydrogen bonds or salt bridges formed between the two molecules. (B) Superimposition of the ancHMALVKIE structure and the ancHMA homology model (grey) in complex with AVR-PikD. (C) Close-up views of the IAQVV/LVKIE region of ancHMALVKIE (green and blue) and ancHMA (green) showcasing differences in binding to AVR-PikD (pink). The selected residues involved in binding are labelled with labels matching the colours of the corresponding molecules. The LVKIE residues are labelled with single-letter amino acid symbols—Ile/Leu-221 (I/L), Ala/Val-222 (A/V), Gln/Lys-228 (Q/K), Val/Ile-229 (V/I), Val/Glu-230 (V/E) for ancHMA/ancHMALVKIE; and Ile-222 (I), Ala-223 (A), Gln-231 (Q), Val-232 (V), Val-233 (V) for Pikm-HMA. Dashed lines represent hydrogen bonds or salt bridges formed between the two molecules.