Fig. 3: Adhesion of Fap2 to Gal-GalNAc-Thr and hTIGIT.
a Concentration-dependent binding of fluorescently labeled Gal-GalNAc-Thr to Fap2-expressing E. coli and to control E. coli that express pAIDA without the Fap2-ECD. Data points represent individual measurements per concentration and dashed lines indicate the mean values. Data analysis and visualization was carried out in R using the ggplot2 package83. b Fluorescence micrographs that show cancer cell binding (HT-29) of Fap2-expressing E. coli. Less binding is observed with control E. coli (left panel. Cell binding is reduced in the presence of excess GalNAc (right panel). The images are representatives of data sets of 36, 48, and 41 micrographs for Fap2-expressing E. coli, control E. coli, and Fap2-expressing E. coli with GalNAc, respectively. Red: E. coli labeled with CellBrite Fix 555, green: Actin labeled with Phalloidin-iFluor 488. Scale bar: 50 µm. Note the unequal distribution of E. coli on HT-29 cells. c Quantification of experiments as in (b), with average integrated fluorescence signal of E. coli bound to HT-29. The number of micrographs (n) is indicated. The mean is shown as red dot and the boxes represent the interquartile range, with the median shown as horizontal line within the box. The distribution of data points is visually represented by violin plots. Statistical evaluation was done using the Games-Howell post-hoc test from the ggstatsplot package82 in R. d Quantification of Fap2-ECD binding to hTIGIT-ECD using surface plasmon resonance. A global fit according to a 1:1 binding model (black solid lines) reveals a KD of ~0.6 µM (Supplementary Table 3). Lower panel: residuals of fit.
