Table 3. Rates of spontaneous CAN1 mutations in pol2-4,eex msh6Δ strains.
|
pol2-4,eex msh6Δ |
||||||
|---|---|---|---|---|---|---|
| pol2-4 msh6Δ | G435C | V522A | T850M | K966Q | A1153D | |
| Transitionsa | ||||||
| G→A (C•dATP) | 360 (1.0) | 150 (0.4) | 20 (0.06) | 18 (0.05) | 120 (0.3) | 25 (0.07) |
| C→T (G•dTTP) | 90 (1.0) | ∼32 (∼0.4) | 16 (0.2) | ∼3 (∼0.04) | 27 (0.3) | ∼5 (∼0.05) |
| Transversionsa | ||||||
| G→T (C•dTTP) | 380 (1.0) | 180 (0.5) | 58 (0.2) | 5 (0.01) | 55 (0.1) | 22 (0.06) |
| C→A (G•dATP) | ∼18 (1.0) | <8 (ND) | <2 (ND) | 7 (ND) | ∼18 (ND) | ∼1 (ND) |
| Frameshifts | ||||||
| +1 | 160 (1.0) | <8 (<0.05) | ∼6 (∼0.04) | ∼3 (∼0.02) | ∼9 (∼0.06) | ∼4 (∼0.02) |
| −1 | <18 (1.0) | <8 (ND) | ∼4 (ND) | 4 (ND) | <5 (ND) | ∼1 (ND) |
| Overall | 1001 (1.0) | 365 (0.36) | 104 (0.10) | 43 (0.04) | 247 (0.25) | 60 (0.06) |
Expressed as the number of Canr mutants per cell division (×10−7). Rates for individual mutation types were calculated by multiplying the overall Canr mutation rate of a strain (last row of table) by the percentage of the corresponding mutation in the CAN1 mutation spectrum from that strain (Table 2). Rates relative to those in pol2-4 msh6Δ are in parentheses. Values were calculated to three decimal places and then rounded to one or two significant figures. < or ∼: incidence values (Table 2) were zero or not significantly different from zero, respectively (P > 0.05, Fisher’s exact test). ND: relative rates could not be reliably determined because mutations of this type were not detected at significant levels in the pol2-4 msh6Δ strain (Table 2).
Base changes in the CAN1 coding sequence are shown with presumed causal mispairs in parentheses (template base•incoming dNTP), if Pol ε catalyzes leading-strand DNA synthesis (Pursell et al. 2007; Kunkel and Burgers 2008; Pavlov and Shcherbakova 2010) initiated from the ARS507 origin of replication (Raghuraman et al. 2001; Yabuki et al. 2002; Kumar et al. 2011; Siow et al. 2012).