TABLE 2.
Properties of FecA mutants
| Mutation | β-Galactosidase activity [Miller units (%)]a |
55Fe3+ transport rate (%)b
|
|
|---|---|---|---|
| Medium copy | Low copy | ||
| None (vector) | 12 (0.7) | 11 | 10 |
| None (wild type) | 1,898 (100) | 100 | 100 |
| ΔL3 (Δ313-328) | 15 (0.8) | 10 | ND |
| ΔL5 (Δ423-433) | 136 (7) | 23 | 16 |
| ΔL71 (Δ517-533) | 16 (0.9) | 7 | ND |
| ΔL72 (Δ519-533) | 15 (0.8) | 6 | ND |
| ΔL81 (Δ563-577) | 15 (0.8) | 7 | ND |
| ΔL82 (Δ568-577) | 15 (0.8) | 8 | ND |
| ΔL9 (Δ616-630) | 695 (37) | 74 | 76 |
| ΔL10 (Δ662-673) | 952 (50) | 48 | 33 |
| ΔL11 (Δ713-727) | 23 (1.2) | 16 | 8 |
| ΔL7ΔL8 (Δ517-533 Δ563-577) | 8 (0.4) | 9 | ND |
| T138A | 1,198 (63) | 46 | 58 |
| R365A | 28 (1.5) | 8 | ND |
| R380A | 15 (0.8) | 8 | ND |
| R438A | 797 (42) | 53 | 73 |
| Q570A | 13 (0.7) | 11 | ND |
| D573A | 1,177 (62) | 97 | 40 |
| K525A | 1,895 (100) | 94 | 126 |
| R578A | 1,556 (82) | 53 | 82 |
| E541A | 1,708 (90) | 112 | 81 |
| E541R | 1,594 (84) | 91 | 72 |
| E587A | 721 (38) | 85 | 87 |
| E587R | 626 (33) | 50 | 47 |
| R150A E541R | 285 (15) | 27 | 42 |
| R150A E587R | 76 (4) | 25 | 29 |
a
Transcription induction of fecA was measured in E. coli AA93 (Δfec pMMO1034 fecA-lacZ) grown in NB containing 1 mM citrate. The values are the averages of three independent experiments. The uninduced values (cells grown in NB lacking citrate) were between 8 (0.4%) and 18 (1%) Miller units.
b
Transport was determined in E. coli IS1031 (fecA) and in E. coli AA93. The transport rate was calculated by subtracting the values after a 1-min incubation from the values after a 16-min incubation; the values given are relative to the wild-type rate (100%). The values are the averages of two independent experiments.