TABLE 4.
Features of the purified PilF complexes and phenotypes of the T. thermophilus pilF mutants
NA, not applicable.
| Strain/protein | Zinc per hexamera | ATPase activityb | Complex formationc | Thermostabilityd |
Piliatione |
Adherencef |
Twitching motilityf |
Transformation frequencyg | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Unfolding (t1) | Unfolding (t2) | 55 °C | 64 °C | 72 °C | 55 °C | 64 °C | 72 °C | 55 °C | 64 °C | 72 °C | |||||
| milliunits/mg | °C | ||||||||||||||
| HB27 | NA | NA | NA | NA | NA | ++ | + | + | ++ | + | + | + | + | + | + |
| ΔpilF::bleo | NA | NA | NA | NA | NA | − | − | − | − | − | − | − | − | − | − |
| Wild type | 6.03 | 54.00 | + | 80.8 | 90.5 | ++ | + | + | ++ | + | + | + | + | + | + |
| C1A | 5.65 | 46.32 | + | 78.6 | 91.0 | +++ | +/− | − | + | +/− | − | + | +/− | − | + |
| C2A | 5.16 | 49.86 | + | 71.6 | 91.2 | ++ | + | − | + | + | − | + | + | − | + |
| HC2A | 5.28 | 49.27 | + | 72.8 | 90.8 | ++ | + | − | + | + | − | + | + | − | + |
| C3A | 5.67 | 46.84 | + | 73.9 | 90.6 | + | +/− | − | + | +/− | − | + | +/− | − | + |
| C4A | 4.73 | 52.62 | + | 70.0 | 90.9 | − | − | − | + | − | − | − | − | − | +++ |
| 2CysA | 1.26 | 53.16 | + | 65.4 | 90.6 | +++ | − | − | + | + | − | − | − | − | + |
| 3CysA | 0.86 | 46.84 | + | 65.5 | 90.3 | +++ | − | − | + | + | − | − | − | − | + |
| 4CysA | 0.28 | 48.25 | + | 66.3 | 90.7 | +++ | − | − | + | + | − | − | − | − | + |
a Zinc content was analyzed by ICP-MS.
b ATPase activity of PilF variants was analyzed by the method described by Heinonen and Lahti (21).
c Complex formation of purified PilF proteins was analyzed by calibrated size exclusion chromatography.
d Thermostability was measured via thermofluor assays.
e Piliation was analyzed by electron microscopy (250 cells).
f Adherence was measured in microtiter adhesion assays. Twitching motility was analyzed on MM containing 1% BSA.
g Transformation frequencies were calculated as transformants per living count. +, wild-type phenotype; ++, increase compared to the wild-type; +++, strong increase compared to the wild-type; +/−, decrease compared to the wild-type; −, lack of the analyzed feature.