(A) Binding of peptide 1 and 2 to heterologously expressed AliD as analyzed by microscale thermophoresis (MST). The concentration of NHS-RED-labeled AliD was kept constant (20 nM), while the concentration of the non-labeled peptides ranged between 7.63x10-6–0.125 mM. Samples were measured using the Monolith NT.115 (NanoTemper Technologies) at 40% LED power and medium MST power at 25° C. The Kd was calculated from three independent measurements, error bars represent the standard deviation. (B) Structural superposition of the two peptide 1 molecules (depicted as capped sticks) bound to AliD monomers A (gray) and B (yellow). The sequence of peptide 1 (FPPQSV) is indicated and numbered. N-term, amino-terminus; C-term, C-terminus. (C) Atomic B factors for peptide 1 as observed in the AliD:peptide 1 complex (monomer B). The Ligand is represented as capped sticks and colored based on the B-factor distribution, ranging from low (blue) to high (red) values. (D) Electron-density map (2mFo-DFc map contoured at 1.0 σ) for each of the two peptide 1 molecules (in green caped sticks) observed in the AliD:peptide 1 complex. The position of each peptide residue is numbered.

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