Data-Driven Prediction and Design of bZIP Coiled-Coil Interactions
Fig 4
Designed bZIP-binding peptides inhibit interactions of native bZIP dimers.
(A) JUN-d1 inhibits the interaction of 10 nM JUN with 50 nM FOS with an IC50 of 245 nM at 37°C. (B) XBP1-d1 inhibits the interaction of 10 nM XBP1 with 50 nM CREBZF with an IC50 of 136 nM at 23°C. (C) ATF4-d1 inhibits the interaction of 10 nM ATF4 with 200 nM FOS with an IC50 of 279 nM at 37°C. The dissociation constants at the indicated temperatures are Kd ≤ 1 nM for FOS-JUN, Kd ≤1 nM for XBP1-CREBZF, and Kd = 60 nM for ATF4-FOS, according to [18]. Fluorescence intensities were measured at both 37°C and 23°C, and the IC50 value was fit and reported for the highest temperature that gave a well-defined lower baseline. The target bZIP in each complex was labeled with the FRET donor (fluorescein), the partner was labeled with the TAMRA FRET acceptor, and the design was unlabeled. Fluorescence emission was monitored at 525 nm and is reported in relative fluorescence units.