TABLE 5.
Expression and export of SOD from M. smegmatis and M. tuberculosis
| Species and strain | SODa | %
Extracellularb
|
Relative
amountc
|
||
|---|---|---|---|---|---|
| Activity gel | SDS-PAGE | Activity gel | SDS-PAGE | ||
| M. smegmatis | |||||
| pNBV1 | M. smegmatis SodA | 10 | 12 | 1.0 | 1.0 |
| sodA pNBV1 | M. smegmatis SodX | 6 | —d | 0.3 | — |
| sodA pNBV1-MsSODA | M. smegmatisSodA | 8 | 4 | 1.1 | 5.6 |
| sodA pNBV1-MtbSodA | M. tuberculosis SodA | 7 | 4 | 1.4 | 1.7 |
| sodA pNBV1-BsSODA | M. smegmatis SodX | 7 | — | 0.3 | — |
| B. subtilis SodA | 6 | 5 | 0.6 | 0.7 | |
| pNBV1-BsSODA | M. smegmatisSodA | 9 | |||
| B. subtilis SodA | 9 | 11 | 0.5 | — | |
| sodA pNBV1-EcSODA | M. smegmatis SodX | 7 | — | 0.2 | — |
| E. coli SodA | 4 | 7 | 1.1 | 1.6 | |
| pNBV1-EcSODA | M. smegmatis SodA | 12 | 14 | ||
| E. coli SodA | 7 | 14 | 1.0 | 2.4 | |
| sodA pNBV1-EcSODX | M. smegmatis SodX | 6 | — | 0.3 | — |
| E. coli SodB | 5 | 3 | 0.9 | 0.8 | |
| pNBV1-EcSODB | M. smegmatis SodA | 10 | 13 | ||
| E. coli SodB | 12 | 15 | 0.8 | 1.0 | |
| M. tuberculosis | |||||
| pNBV1 | M. tuberculosis SodA | 15 | 20 | 1.0 | 1.0 |
| pNBV1-MsSODA | M. tuberculosis SodA | 15 | 23 | ||
| M. smegmatis SodA | 20 | 20 | 3.2 | 7.9 | |
| pNBV1-EcSODB | M. tuberculosis SodA | 14 | 20 | ||
| E. coli SodB | 16 | 19 | 0.5 | 2.2 | |
Many of the strains have two SOD activities which often could be analyzed separately. The SOD activity present in the M. smegmatis sodA mutant, which was not evident in the wild-type strain, is designated SodX.
The percentages of extracellular SOD, from both SOD activity gels and SDS-polyacrylamide gels (Fig. 7), were determined with NIH Image software (version 1.62). Because B. subtilis SodA and M. smegmatis SodA have nearly identical mobilities on SDS-polyacrylamide gels, the extracellular percentage is based on the combination of the two SODs.
For M. tuberculosis and M. smegmatis wild-type strains, relative amount refers to the amount of recombinant SOD compared with the endogenous M. tuberculosis or M. smegmatis SodA, respectively (i.e., an internal comparison). For the M. smegmatis sodA strains, “relative amount” refers to the amount of recombinant SOD compared with the amount of M. smegmatis SodA produced by a culture of the M. smegmatis pNBV1 wild-type strain grown under the same conditions.
—, unable to analyze because a band could not be identified or was not clearly resolved.