Table 1. Effect of amino acid changes in Mlh1 and Pms1 on spontaneous mutagenesis.
| Genotype | Lys+ reversion | His+ reversion | Canr mutation | |||
|---|---|---|---|---|---|---|
| Reversion rate (×10–6) | Fold increase | Reversion rate (×10–8) | Fold increase | Mutation rate (×10–8) | Fold increase | |
| Wild-type | 0.19 (0.15–0.21) | 1 | 1.0 (0.59–1.3) | 1.0 | 25 (18–31) | 1.0 |
| pms1Δ | 1400 (1000–2000) | 7500 | 61 (48–92) | 63 | 370 (300–960) | 15 |
| pms1-K328E | 11 (8.3–19) | 60 | 3.4 (3.0–7.9) | 3.5 | 25 (20–28) | 1.0 |
| mlh1Δ | 1500 (1200–2100) | 7800 | 74 (65–85) | 76 | 500 (460–870) | 20 |
| mlh1-R274E | 320 (280–370) | 1700 | 6.7 (5.4–8.1) | 6.9 | 88 (76–230) | 3.5 |
| mlh1-R273E,R274E | 2200 (1900–2700) | 12000 | 58 (46–140) | 60 | 430 (360–630) | 17 |
Mutation rates were measured for haploid strains with mutations in the chromosomal MLH1 or PMS1 genes and in the isogenic wild-type strain E134 (25). Rates are given as medians for at least nine independent cultures, with 95% confidence limits in parentheses. The fold increase is relative to the wild-type mutation rate.