Fig. 3: PVC-mediated protein delivery is highly specific.
From: Programmable protein delivery with a bacterial contractile injection system
a,b, Specificity assay for PVCs based on artificial receptors. a, Schematic of the experiment. A panel of epitope tags was inserted into the distal binding ___domain of the tail fibre (amino acids 403–476 of Pvc13), and a panel of the associated receptors (anti-epitope tag antibodies) was displayed on the surface of HEK 293FT cells. As in Figs. 1g and 2a, PVC activity was measured as GFP expression following delivery of Cre into cells harbouring loxP-GFP. b, Only correct epitope–antibody pairings resulted in efficient PVC-mediated delivery of Cre, indicating that PVC activity requires a specific interaction between the tail fibre and the target cell. Scale bar, 500 μm. c, Specificity assay for PVCs based on an endogenous receptor. Right, PVCs loaded with Pdp1 and Pnf were retargeted towards human EGFR (with Pvc13–E01-DARPin, as in Fig. 2a) and administered to EGFR+ (A431 and A549) and EGFR− (Jurkat and 3T3) cell lines. Cytotoxicity was observed only in the EGFR+ cell lines, and only when Pvc13 contained the anti-EGFR DARPin. No cytotoxicity was observed with PVCs harbouring truncated Pvc13 lacking a binding ___domain (amino acids 403–476) (left). d, Display of a target receptor is sufficient to sensitize cells to PVCs. A cell line (3T3) immune to PVC delivery (c) was transfected with a plasmid containing human EGFR and was exposed to EGFR-targeting PVCs; this time, the cells exhibited a loss of viability. Data are mean (b,c) or mean ± s.d. (d) with n = 2 (b,c) or n = 3 (d) biological replicates; two-way ANOVA with Bonferroni post hoc test. NS, not significant.
