FIGURE 2.

Representative single-channel electrical recordings with the wild-type (WT-FhuA) and single-deletion mutants of FhuA protein. A, WT-FhuA; B, FhuAΔ1–160; C, FhuAΔ335–355. The dashed lines indicate the current levels for the open (S₂) and gated (S₁) sub-states in B and C. Right panels show all-point current amplitude Gaussian histograms with the most probable sub-states of the channels. The expanded trace illustrates the last 60 ms of the trace from B at a greater time resolution. The dashed lines were assigned based upon the peaks from the all-points current amplitude Gaussian histograms from the right panels of B and C. The buffer solution was 1 m KCl, 10 mm potassium phosphate, pH 7.4. The transmembrane potential was +40 mV. Single-channel electrical traces were filtered at 1 kHz.