TABLE 2.
Complementation test in E. coli of plasmids expressing modified versions of S. typhimurium hemA
| Plasmid | Construct | Hem phenotypea
|
|
|---|---|---|---|
| Uninduced | Induced | ||
| pTE570 | PBAD vector | − | − |
| pTE694 | PBAD-hemA[WT] | + | ++++ |
| pTE713 | PBAD-hemA[KK] | ++++ | ++++b |
| pTE714 | PBAD-hemA[DE]c | − | ++ |
| pTE715 | PBAD-hemA[−L] | − | − |
| pTE717 | PBAD-hemA[N-myc] | + | ++++ |
| pTE739 | PBAD-hemA[AA] | + | ++++ |
Cultures of strain TE7054 (E. coli K-12 hemA Δara) carrying the indicated plasmids were grown to saturation in LB plus ampicillin (100 μg/ml) and ALA (150 μM). After dilution in phosphate-buffered saline, about 500 CFU was then plated on each of two NB-ampicillin plates (NB medium is selective for the Hem+ phenotype). A disc was placed in the center of one plate, and 10 μl of 20% arabinose was pipetted onto the disc. Colony size (diameter) was scored after 16 h. +, <0.5 mm; ++, ≈1 mm; ++++, ≈2 mm.
Colonies were large at the edge of the plate and smaller close to the disc where the inducer was applied.
See the legend to Fig. 1 for a description of this construct.