Extended Data Fig. 8. Mutational analysis of the Vs.4:cGAMP complex.
a, Isothermal calorimetry (ITC) data from titrating cGAMP into a solution of the indicated Vs.4 mutant. Each experiment was performed at least twice and global analysis was used to determine KD, ΔH, and ΔS. Analysis of the F33A mutant indicated high incompetent fraction (0.496), as indicated with an *. Cases where no binding was observed are denoted as having no signal (n.s). b, Representative examples of raw titration traces (top) and integrated data (bottom, data points depict integrated heat of injection and error bars depict the weighted rmsd of the difference between predicted and measured values) of two independent ITC experiments reported in a. Titration data for WT Vs.4 is shown in Fig. 3b. c, Analytical ultracentrifugation of Vs.4 mutants. Vs.4 (WT) forms a hexamer that is stable on the time scale of the sedimentation experiment at 15 μM with a sedimentation coefficient of 4.3 and an estimated MW of 59 kDa (61.8 kDa expected). Mutations to the hexamerization interface causes dramatically reduced sedimentation coefficients, consistent with disruption of the quaternary structure.