Fig. 3.

Mutant PYR1 receptor–ligand interactions can be mapped using large-scale sensor screens. (A) Screening outcomes: ligand hits per receptor sequence, number of receptors identified per hit ligand, and the minimum dose–response of receptor hits during validation (each sensor strain was tested for ligand-dependent growth on 1, 10, 100 µM ligand). (B) Sensor mutations are broadly distributed throughout the PYR1 binding pocket; the top panel shows mutations per binding pocket residue, and the bottom panel maps the frequency of specific mutations per residue for the 553 receptors isolated. (C) Selected binding-pocket sequences for ligands that yielded ≥ 4 receptor hits. WT residues are shown at the top; colored boxes denote basic (blue), hydrophobic (green), polar (orange), and aromatic (gray) substitutions. (D) Sensor-binding-pocket mutations are tailored to their target ligands. Selection for mutational bias in each sensor–ligand set was quantified by calculating the Shannon diversity of mutation counts per position across receptors, with lower values indicating more positionally clustered mutational patterns (i.e., sensors for a ligand tend to have mutations in the same binding pocket locations). The analysis was performed for the 66 ligands with four or more sensors isolated (n = 502 receptor–ligand interactions). The null model shows Shannon diversity values calculated from randomly permuted receptor–ligand assignments (P < 6.4 × 10⁻¹³; two-sided Wilcoxon rank-sum test). R code is available at https://github.com/cutlersr/PYR1_sensor_screen.