1. Mutation rates are difficult to measure in riboviruses, the largest class of human pathogens. In particular, the question of whether riboviruses share a common genomic mutation rate has resisted resolution. After many efforts, we established a model system using the phage Q growing on the bacterium Escherichia coli. As expected from a ribovirus, mutation rates are very high, about 0.04 per genome replication. The ratios of different kinds of mutations differ from those seen in most other organisms, with a particularly high ratio of transition to transversion base substitutions and with very few indels with a bias towards single-base insertions. We were also able to test the hypothesis that riboviruses replication by a stamping-machine process rather than by exponential replication, with the stamping-machine hypothesis supported. 2. In recent years, several groups have characterized spontaneous mutations using whole-genome DNA sequencing. The methods have potential pitfalls and the results sometimes appear to contradict previous reports using more fully established methods. An example of such a contradiction was described and attributed to the unrealized loss of mutations during the passage of the cultures.

Project Start
Project End
Budget Start
Budget End
Support Year
13
Fiscal Year
2012
Total Cost
$765,897
Indirect Cost
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Drake, John W (2012) Contrasting mutation rates from specific-locus and long-term mutation-accumulation procedures. G3 (Bethesda) 2:483-5
García-Villada, Libertad; Drake, John W (2012) The three faces of riboviral spontaneous mutation: spectrum, mode of genome replication, and mutation rate. PLoS Genet 8:e1002832
Burch, Lauranell H; Zhang, Leilei; Chao, Frank G et al. (2011) The bacteriophage T4 rapid-lysis genes and their mutational proclivities. J Bacteriol 193:3537-45
García-Villada, Libertad; Drake, John W (2010) Mutational clusters generated by non-processive polymerases: A case study using DNA polymerase betain vitro. DNA Repair (Amst) 9:871-8
Drake, John W (2009) Avoiding dangerous missense: thermophiles display especially low mutation rates. PLoS Genet 5:e1000520
Mackwan, Reena R; Carver, Geraldine T; Kissling, Grace E et al. (2008) The rate and character of spontaneous mutation in Thermus thermophilus. Genetics 180:17-25