Table 1. Ndt80 mutations and their effect in vitro and in vivo.
| Mutant | MSE DNA contacta | DNA-binding affinityb (%) | Meiosisc (%) | Dityrosined | Activitye (%) |
|---|---|---|---|---|---|
| WT | 100 | 70 | + | 100 | |
| K50A | T9 bb | 30 | 41 | +/– | 88 |
| K54A | G8 bb | 50 | 24 | +/– | 100 |
| I55A | T9,G10 bb | 100 | 54 | +/– | ND |
| P57A | T11 vdw | 35 | <1 | – | 28 |
| R58A | T12 A14 bs /A15 bb | 35 | <1 | – | 25 |
| S59A | LR | 14 | <1 | – | 80 |
| T60A | A13 A14 bb | 100 | 20 | + | ND |
| R97A | G10 bb | 33 | <1 | – | 20 |
| K110A | C5 bb | 100 | 10 | – | ND |
| R111A | G8 bs / G10 bb | 5 | <1 | – | 20 |
| N112A | T9 bb | 100 | <1 | – | ND |
| Y113F | T11 G10 bb | 20 | <1 | – | ND |
| K176A | T12 T13 bb | 50 | 27 | + | ND |
| R177A | G10 bs / G10 bb | 4 | <1 | – | 15 |
| R202A | A15 bb | 100 | 5 | – | 128 |
| E203A | A15 bb | 100 | 52 | + | ND |
| S205A | A15 bb | 100 | 42 | + | ND |
| N206A | T11 T12 A15 bb | 100 | 5 | – | 70 |
| R208A | C16 bb | 50 | <1 | – | 27 |
| N209A | C16 bb | 100 | 47 | + | ND |
| K212A | C16 bb | 100 | 7 | – | 89 |
| R254A | T11 bb | 7 | <1 | – | ND |
| S259A | G6 bb | 100 | 44 | + | 79 |
| S260A | LR | 100 | 43 | + | ND |
| R326A | G6 T7 bs/C5 bb | 50 | <1 | – | 30 |
| Y331A | T9 bb | 100 | 38 | + | 172 |
aContacts with the MSE are given with the base number corresponding to the schematic in Figure 2. The symbols bs, bb, and vdw represent base-specific, backbone contacts and van der Waals contacts, respectively. The interactions designated by bs or bb are direct hydrogen bonds or water-mediated hydrogen bonds (refer to Fig. 2).
bDNA-binding affinity of the mutants in comparison to wild-type protein.
cPercentage of cells containing two or more DAPI-staining foci after 24 h in sporulation media.
dCells were monitored for the presence of dityrosine fluorescence after 24 h in sporulation media. ‘+’ wild-type levels of fluorescence, ‘+/–’ low but detectable levels of fluorescence, ‘–’ no fluorescence.
eTranscriptional activation of a MSE-regulated promoter in comparison to the wild-type protein. ND indicates that the specified mutant was not tested in this assay.