TABLE 2.
Effects of an fnr null allele on activity of the K. pneumoniae NifL protein in different E. coli backgrounds
| Strain | Relevant genotypea | Presence of oxygen | Expression of nifH′-′lacZ (U/ml/OD600 U)b | Doubling time (h) |
|---|---|---|---|---|
| NCM1528 | Wild type/Ptac-nifLA | − | 3,000 ± 100 | 5.0 |
| NCM1528 | Wild type/Ptac-nifLA | + | 60 ± 5 | 2.0 |
| NCM1527 | Wild type/Ptac-nifA | − | 5,300 ± 200 | 4.8 |
| NCM1527 | Wild type/Ptac-nifA | + | 5,118c | 2.1 |
| RAS2 | Wild type/Ptac-nifL mutant nifA | − | 2,950 ± 120 | 5.2 |
| RAS2 | Wild type/Ptac-nifL mutant nifA | + | 2,900 ± 50 | 2.0 |
| RAS8d | fnr mutant/Ptac-nifA | − | 4,800 ± 100 | 4.9 |
| RAS8d | fnr mutant/Ptac-nifA | + | 5,200 ± 200 | 2.2 |
| RAS6d | fnr mutant/Ptac-nifL mutant nifA | − | 2,800 ± 100 | 5.0 |
| RAS6d | fnr mutant/Ptac-nifL mutant nifA | + | 3,000 ± 200 | 2.0 |
| RAS7d | fnr mutant/Ptac-nifLA | − | 100 ± 10 | 5.0 |
| RAS7d | fnr mutant/Ptac-nifLA | + | 30 ± 3 | 2.0 |
| RAS9d | fnr mutant/Ptac-nifLA/Plac fnr | − | 3,000 ± 100 | 5.2 |
| RAS10d | fnr mutant/Ptac-nifLA/Ptet fnr | − | 2,870 ± 70 | 5.2 |
| RAS11d | fnr mutant/Ptac-nifLA/pMCL210 | − | 66 ± 5 | 5.5 |
| RAS12d | fnr mutant/Ptac-nifLA/pACYC184 | − | 70 ± 6 | 5.5 |
| RAS22 | Wild type/Ptac-nifLA | − | 3,500 ± 80 | 5.0 |
| RAS22 | Wild type/Ptac-nifLA | + | 70 ± 5 | 2.2 |
| RAS23 | Wild type/Ptac-nifA | − | 5,900 ± 250 | 5.1 |
| RAS23 | Wild type/Ptac-nifA | + | 5,725 ± 150 | 2.2 |
| RAS24 | Wild type/Ptac-nifL mutant nifA | − | 3,400 ± 200 | 4.9 |
| RAS24 | Wild type/Ptac-nifL mutant nifA | + | 2,800 ± 150 | 2.1 |
| RAS15e | fnr mutant/Ptac-nifA | − | 5,300 ± 200 | 5.6 |
| RAS15e | fnr mutant/Ptac-nifA | + | 5,130 ± 150 | 2.1 |
| RAS25e | fnr mutant/Ptac-nifL mutant nifA | − | 3,200 ± 200 | 5.0 |
| RAS25e | fnr mutant/Ptac-nifL mutant nifA | + | 3,400 ± 100 | 2.2 |
| RAS14e | fnr mutant/Ptac-nifLA | − | 160 ± 10 | 5.3 |
| RAS14e | fnr mutant/Ptac-nifLA | + | 40 ± 5 | 2.0 |
| RAS16e | fnr mutant/Ptac-nifLA/Ptet-fnr | − | 3,200 ± 100 | 5.2 |
| RAS17e | fnr mutant/Ptac-nifLA/pACYC184 | − | 190 ± 10 | 5.4 |
a
nifL mutant nifA, nifLC184S/C187SnifA (see Materials and Methods); Plac, Ptac, or Ptet, under the control of the lac, tac, or tet promoter, respectively.
b
Data are presented as mean values (± standard errors) of three independent experiments.
c
Determined by He et al. (9).
d
Strain contains the fnr null allele from M182 (fnr::Tn10) (16).
e
Strain contains the fnr null allele from RM101 (30).