MTS Effects on the Conductance of Colicin Ia Cysteine-mutant Channels
| Percent Conductance Change . | . | . | . | . | . | . | . | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| . | MTSET . | . | MTSES . | . | MMTS . | . | MTS-glucose . | |||||||
| Mutant | Macroscopic | Single | Macroscopic | Single | Macroscopic | Single | Macroscopic | |||||||
| T573C | −47 ± 4 (3) | −58 ± 2 (6) | +2 ± 2 (2) | — | NE (2) | — | — | |||||||
| G577C | −48 ± 6 (2) | −82 ± 1 (3) | −29 ± 8 (3) | −45 ± 6 (26) | −29 ± 6 (3) | −33.7 ± 0.5 (3) | −74 ± 6 (2) | |||||||
| N578C | −8 ± 4 (2) | −56 ± 10 (4)* | +5 ± 2 (3)* | — | −6.5 ± 0.5 (2) | — | — | |||||||
| T581C | −62 ± 2 (3) | −75 ± 1 (5) | −20 ± 2 (2) | — | −16 ± 7 (4) | −12 ± 3 (4) | −28 ± 10 (3) | |||||||
| A582C | −5.5 ± 0.5 (2) | −25 ± 5 (3) | +4 ± 4 (3) | — | NE (3) | — | — | |||||||
| A585C | −7 ± 2 (3) | −11 ± 5 (10) | +23 ± 2 (3) | +31 ± 6 (28) | −4 ± 1 (4) | — | — | |||||||
| F588C | −23 ± 2 (6) | −25 ± 5 (9) | +12 ± 25 (3) | — | NE (4) | — | — | |||||||
| Y601C | +47 ± 3 (3) | +37 ± 5 (7) | +92 ± 2 (2) | +76 ± 3 (4) | +16 ± 2 (3) | — | — | |||||||
| M605C | −38 ± 13 (2) | −40 ± 6 (7) | +15 ± 2 (3) | — | −12 ± 7 (4) | — | — | |||||||
| G609C | −63 ± 3 (4) | −74 ± 6 (4) | −31 ± 6 (2) | −59 ± 2 (8) | −32 ± 7 (4) | −35 ± 4 (3) | −49.5 ± 0.5 (2) | |||||||
| I612C | −68 ± 10 (3) | −73 ± 10 (6) | +9.5 ± 0.5 (2) | — | NE (2) | — | — | |||||||
| Percent Conductance Change . | . | . | . | . | . | . | . | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| . | MTSET . | . | MTSES . | . | MMTS . | . | MTS-glucose . | |||||||
| Mutant | Macroscopic | Single | Macroscopic | Single | Macroscopic | Single | Macroscopic | |||||||
| T573C | −47 ± 4 (3) | −58 ± 2 (6) | +2 ± 2 (2) | — | NE (2) | — | — | |||||||
| G577C | −48 ± 6 (2) | −82 ± 1 (3) | −29 ± 8 (3) | −45 ± 6 (26) | −29 ± 6 (3) | −33.7 ± 0.5 (3) | −74 ± 6 (2) | |||||||
| N578C | −8 ± 4 (2) | −56 ± 10 (4)* | +5 ± 2 (3)* | — | −6.5 ± 0.5 (2) | — | — | |||||||
| T581C | −62 ± 2 (3) | −75 ± 1 (5) | −20 ± 2 (2) | — | −16 ± 7 (4) | −12 ± 3 (4) | −28 ± 10 (3) | |||||||
| A582C | −5.5 ± 0.5 (2) | −25 ± 5 (3) | +4 ± 4 (3) | — | NE (3) | — | — | |||||||
| A585C | −7 ± 2 (3) | −11 ± 5 (10) | +23 ± 2 (3) | +31 ± 6 (28) | −4 ± 1 (4) | — | — | |||||||
| F588C | −23 ± 2 (6) | −25 ± 5 (9) | +12 ± 25 (3) | — | NE (4) | — | — | |||||||
| Y601C | +47 ± 3 (3) | +37 ± 5 (7) | +92 ± 2 (2) | +76 ± 3 (4) | +16 ± 2 (3) | — | — | |||||||
| M605C | −38 ± 13 (2) | −40 ± 6 (7) | +15 ± 2 (3) | — | −12 ± 7 (4) | — | — | |||||||
| G609C | −63 ± 3 (4) | −74 ± 6 (4) | −31 ± 6 (2) | −59 ± 2 (8) | −32 ± 7 (4) | −35 ± 4 (3) | −49.5 ± 0.5 (2) | |||||||
| I612C | −68 ± 10 (3) | −73 ± 10 (6) | +9.5 ± 0.5 (2) | — | NE (2) | — | — | |||||||
Percent change in macroscopic and single-channel conductance of colicin Ia cysteine mutants due to reaction with MTS compounds. All results were obtained in 1 M KCl, pH 7.2 buffer, except those marked with an asterisk, which were in 100 mM KCl buffer. MTS reagents were added to the cis compartment for T573C and I612C and to the trans compartment for all of the other mutants. The percent change in conductance is given as the mean ± standard deviation, with n (the number of macroscopic experiments or the number of single-channel reaction events) in parentheses. NE means no effect. The holding potential during MTS addition was in the range of 20–80 mV.