Table 4.
Comparison of the pore forming properties of different RTX toxins in lipid bilayer membranes.
| Toxin | SCC | IS | VG | PD |
|---|---|---|---|---|
| RtxA K. kingae | 400 pS (0.1 M KCl)* | Cation select PK/PCl = 3.5* | 30–40 mV* | 1.9 nm (a)* |
| HylA E. coli | 500 pS (0.15 M KCl) [46] | Cation select [46] PK/PCl = 9 | <100 mV [46] | 1.4–3 nm [68] (b) |
| EHEC-Hly E. coli EHEC | 500 pS (0.15 M KCl) [57] | Cation select [57] PK/PCl = 13 | No data | 2.6 nm [57] (b,c) |
| ApxI A. pleuropneumoniae | 540 pS (0.15 M KCl) [56] | Cation select [56] PK/PCl = 5.7 | No data | 2.4 nm [56] (c) |
| ApxII A. pleuropneumoniae | 620 pS (0.15 M KCl) [56] | Cation select [56] PK/PCl = No data | No data | 2.5 nm [56] (c) |
| ApxIII A. pleuropneumoniae | 95 pS (0.15 M KCl) [56] | Cation select [56] PK/PCl = 9.6 | No data | 1.8 nm [56] (c) |
| CyaA B. pertussis | 27 pS (1M KCl) [29] | Cation select [29] PK/PCl= 9–11 | No data | 0.6–0.8 nm [29, 78] (b,c) |
| Rtx P. vulgaris | 500 pS (0.15 M KCl) [45] | Cation select [45] (PK/PCl = 9.5) | ≥ 40 mV [45] | > 1 nm [45] (c) |
| Rtx M. morganii | 500 pS (0.15 M KCl) [45] | Cation select [45] (PK/PCl = 10) | ≥ 40 mV [45] | > 1 nm [45] (c) |
| Lkt A. actinomycetemcomitans | 406 pS (0.14 M NaCl, 0.01 M CaCl2) [58] | No data | No data | No data |
The biophysical properties such as single channel conductance (SCC), ion selectivity (IS), voltage-dependent gating (VG), and the pore diameter (PD) were compared for several RTX toxins. The references to the original studies are included, while the results included in this study are marked with an asterisk (*). The SCC showed in the Table refers to the open state of the pore with higher conductance. The PK/PCl values shown in the Table are referred to experiments performed in KCl solutions. The values for the pore diameter were obtained using the following methods; (a) partition experiments with NEs, (b) Osmotic protection experiments and (c) mobility sequence of different cations.