Table 1.
Effect of the sulfhydryl reagent MTSES on leukocidin pores with cysteine-substituted subunits: single-channel and macroscopic currents
| Pore | LukF-S124C/WT LukS | WT LukF/LukS-A122C |
| Isa | 145 ± 6 | 154 ± 6 |
| ΔIs(1)b | 3.0 ± 0.7 | 2.8 ± 0.6 |
| ΔIs(2)b | 3.3 ± 0.5 | 3.1 ± 0.5 |
| ΔIs(3)b | 3.7 ± 0.4 | 3.5 ± 0.4 |
| ΔIs(4)b | 4.3 ± 0.6 | 4.0 ± 0.5 |
| ΔIs*(4)c | 4.4 ± 0.6 | 4.1 ± 0.6 |
| ΔIs*(3)c | 3.7 ± 0.3 | 3.3 ± 0.5 |
| ΔIs*(2)c | 3.2 ± 0.5 | 3.2 ± 0.4 |
| ΔIs*(1)c | 3.1 ± 0.8 | 2.8 ± 0.5 |
| ΣΔIs/Isd | 10 ± 1 | 8.8 ± 0.6 |
| ΔIm/Ime | 9.9 ± 1.2 | 8.5 ± 0.7 |
a Mean single-channel current in pA (± SD) at −60 mV.
b Mean blockade in pA (± SD) after each modification step with MTSES. The numbering of the four steps is the same as shown in Figure 3 ▶. All experiments showed four steps except one with Luk F-S124C/WT LukS, in which three steps were seen in 1 of 12 experiments. In the latter experiment, three steps were also seen during the reversal by DTT. For wild-type LukF/LukS-A122C, 9 experiments were done.
c Mean increase in current in pA (± SD) after each reversal step by DTT. The numbering of the four steps is the same as shown in Figure 3 ▶.
d Mean total extent of blockade (% ± SD) in the single-channel experiments after completion of the reaction with MTSES.
e Mean total extent of blockade (% ± SD) in the macroscopic current experiments after completion of the reaction with MTSES (for details, see Figure 4 ▶).