TABLE 2.
A dnaN159 mutant strain requires the polymerase, but not the 5′ exonuclease activity of DNA polymerase I
| Straina |
polA allele located on:
|
No. of tnaA300::Tn10 transductants (Tcr CFU)b using:
|
||
|---|---|---|---|---|
| Chromosome | F factor | P1 vir (tnaA300::Tn10 dnaN+) | P1 vir (tnaA300::Tn10 dnaN159)c | |
| MG1655 | polA+ | None | 376 | 1,720 (18/20) |
| JW165 | polA+ | None | 12 | 307 (28/29) |
| JW164 | polA1 (polA 5′ exo) | None | 174 | 460 (0/12)d |
| CJ278 | ΔpolA::kan | None | 23 | 146 (0/60)d |
| CJ225 | ΔpolA::kan | polA+ | 2,744 | 6,456 (75/82) |
| CJ231 | ΔpolA::kan | polA1 (polA 5′ exo) | 760 | 318 (0/86) |
| CJ233 | ΔpolA::kan | polA Klenow | 2,106 | 9,744 (61/76) |
a
Strains are described in Table 1; JW165 and JW164 are isogenic with each other except at polA.
b
Tcr, tetracycline resistant.
c
Individual clones were picked and transferred (in duplicate) onto LB plates supplemented with tetracycline and incubated overnight at 30 or 42°C. Values in parentheses indicate the number of temperature-sensitive clones observed relative to the total number transferred.
d
Approximately 50% (10 of 22) of the JW164 dnaN159 transductants and approximately 20% (18 of 78) of the CJ278 dnaN159 transductants did not grow at either 30 or 42°C when transferred to LB plates.