TABLE 1.
Relative activities of ColE1, Col10, Col10, and mutagenized ColE1 on E. coli in the absence of immunity protein or on E. coli expressing Imm or Cti
| Section | Colicin
|
Relative activities on E. coli expressinga:
|
|||
|---|---|---|---|---|---|
| Wild type | Mutation result | No protein | Imm | Cti | |
| A | |||||
| ColE1 | 4 (5)∗ | Im | 1∗∗ | ||
| Col10 | 4 (5) | 4 (5) | Im | ||
| ColE1-Col10(419–503) | 3 (5) | 3 (4) | Im | ||
| ColE1 mutants | |||||
| B | 419 VK--Db | IT--E | 4 (5) | Im | 1 (2) |
| 429 DQFAKY | EKISRA | 4 (5) | Im | 1 | |
| 437 I--HV | V--YL | 4 (5) | Im | 1 (2) | |
| 448 VSDI | WDGT | 4 (5) | 2 | (1)c | |
| 448 VSDI--IKD | WDGT--GLK | 4 (5) | 2 | (1) | |
| 454 IKD | GLK | 4 (5) | Im | 1 | |
| 465 L----K-A-A | V----S-V-F | 4 (5) | Im | (1) | |
| 470 K-A-A | S-V-F | 4 (5) | Im | (1) | |
| 477 S-Y-V | A-K-I | 4 (5) | Im | 1 (2) | |
| 483 L--LLA-TT--I | M--FIV-AP--F | 4 | Im | 1 | |
| 486 LLA-TT--I-----V | FIV-AP--F-----I | 4 | Im | 1 | |
| C | 448 V | W | 4 (5) | 2 | 1 |
| 449 S | D | 4 (5) | Im | 1 | |
| 450 D | G | 4 (5) | Im | 1 | |
| 451 I | T | 4 (5) | Im | 1 | |
| 449 SDI--IKD | DGT--GLK | 4 (5) | Im | (1) | |
| D | 448 V | Y | 4 (5) | 2 | (1) |
| 448 V | R | 4 (5) | 2 | 2 (3) | |
| E | 448 VSDI--IKD/ | WDGT--GLK/ | 4 | 2 | (1) |
| 419 VK--D | IT--E | ||||
| 448 VSDI--IKD/ | WDGT--GLK/ | 3 (4) | 1 (2) | Im | |
| 429 DQFAKY | EKISRA | ||||
| 448 VSDI--IKD/ | WDGT--GLK/ | 4 | 1 | Im | |
| 437 I--HV | V--YL | ||||
| 448 VSDI--IKD/ | WDGT--GLK/ | 4 | 2 | Im | |
| 470 K-A-A | S-V-F | ||||
| 448 VSDI--IKD/ | WDGT--GLK/ | 4 (5) | 2 | (1) | |
| 486 LLA-TT--I | FIV-AP--F | ||||
The amount of protein used for each assay was adjusted to yield similar levels of activity toward E. coli pT7-7, although the cytotoxicity per milligram of protein varied. The ColE1-Col10(419–503) mutant exhibited a 20-fold reduction relative to wild-type ColE1 and Col10. The mutants listed in sections B, C, D, and E exhibited reductions in cytotoxicity relative to the wild type of 2- to 5-fold, 0, 0, and 7- to 10-fold, respectively. ∗ and ∗∗, 104-fold-diluted (105-fold-diluted in parentheses) and 10-fold-diluted, respectively, colicin samples yielded a clear (slightly turbid) zone on indicator plates; Im, immune phenotype in which no indication of zone clearing with undiluted colicin was detected.
The residue number of the first mutagenized amino acid in each series is indicated on the left. The locations of unmutagenized amino acids are indicated by hyphens.
The sample yielded slightly turbid spots at 0- and 10-fold dilutions.