TABLE 3.
Strain | Sp act (pmol mg−1 min−1) of enzyme:
|
|
---|---|---|
WS | DGAT | |
E. coli BL21(DE3) | ||
pET23a | 0.4 ± 0.1 | 0.2 ± 0.0 |
pET23a::atfA1 | 308.2 ± 37.9 | 131.7 ± 4.3 |
pET23a::atfA2 | 237.0 ± 30.5 | 4.6 ± 0.8 |
pET23a::atfA1ΩKm | 1.0 ± 0.5 | 0.3 ± 0.1 |
pET23a::atfA2ΩSm | 4.9 ± 0.3 | 0.3 ± 0.1 |
A. borkumensis | ||
SK2 | 64.0 ± 8.1 | 17.2 ± 0.3 |
atfA1ΩKm | 11.3 ± 1.4 | 2.5 ± 0.2 |
atfA2ΩSm | 38.5 ± 1.2 | 10.1 ± 1.6 |
atfA1ΩKmatfA2ΩSm | 0.4 ± 0.2 | 1.6 ± 0.8 |
Assays were done employing crude extracts corresponding to 50 μg total protein for recombinant E. coli strains or 100 μg total protein for pyruvate-grown A. borkumensis strains. Data are mean values ± standard deviations from experiments done in triplicate. Control experiments without addition of acyl acceptor substrates revealed WS activities of 14.5 and 6.4 pmol mg−1 min−1 and DGAT activities of 10.3 and 0.3 pmol mg−1 min−1 for E. coli strains expressing atfA1 and atfA2, respectively. One picomole per milligram per minute corresponds to 117.66 and 235.32 cpm for E. coli and A. borkumensis strains, respectively.