Highly mutagenic replication by DNA polymerase V (UmuC) provides a mechanistic basis for SOS untargeted mutagenesis.

Abstract:

When challenged by DNA-damaging agents, Escherichia coli cells respond by inducing the SOS stress response, which leads to an increase in mutation frequency by two mechanisms: translesion replication, a process that causes mutations because of misinsertion opposite the lesions, and an inducible mutator activity, which acts at undamaged sites. Here we report that DNA polymerase V (pol V; UmuC), which previously has been shown to be a lesion-bypass DNA polymerase, was highly mutagenic during in vitro gap-filling replication of a gapped plasmid carrying the cro reporter gene. This reaction required, in addition to pol V, UmuD', RecA, and single-stranded DNA (ssDNA)-binding protein. pol V produced point mutations at a frequency of 2.1 x 10(-4) per nucleotide (2.1% per cro gene), 41-fold higher than DNA polymerase III holoenzyme. The mutational spectrum of pol V was dominated by transversions (53%), which were formed at a frequency of 1.3 x 10(-4) per nucleotide (1. 1% per cro gene), 74-fold higher than with pol III holoenzyme. The prevalence of transversions and the protein requirements of this system are similar to those of in vivo untargeted mutagenesis (SOS mutator activity). This finding suggests that replication by pol V, in the presence of UmuD', RecA, and ssDNA-binding protein, is the basis of chromosomal SOS untargeted mutagenesis.

Polymerases:

Topics:

Fidelity, Accessory Proteins/Complexes, Nucleotide Incorporation

Status:

new topics/pols set partial results complete validated

Results:

Polymerase Reference Property Result Context
Eco Pol V Maor-Shoshani A2000 Tagged Yes
Eco Pol V Maor-Shoshani A2000 Frameshift Error Rate 2.3E-05 errors/bp
Eco Pol V Maor-Shoshani A2000 Tag Name MBP
Eco Pol V Maor-Shoshani A2000 Overall Error Rate 0.02325 errors/bp
Eco Pol V Maor-Shoshani A2000 Nucleotide Substitution Rate 0.00019 errors/bp
Eco Pol V Maor-Shoshani A2000 Full length or truncated Full length
Eco Pol V Maor-Shoshani A2000 Other accessory protein(s) UmuD′, RecA, and SSB
Eco Pol V Maor-Shoshani A2000 Gap Filling Yes
Eco Pol III Maor-Shoshani A2000 Frameshift Error Rate 1.4E-06 errors/bp
Eco Pol III Maor-Shoshani A2000 Overall Error Rate 0.00098 errors/bp
Eco Pol III Maor-Shoshani A2000 Overall Error Rate 0.00081 errors/bp
Eco Pol III Maor-Shoshani A2000 Nucleotide Substitution Rate 3.8E-06 errors/bp
Eco Pol I Maor-Shoshani A2000 Overall Error Rate 0.00138 errors/bp
Eco Pol I Maor-Shoshani A2000 Overall Error Rate 0.00078 errors/bp
Eco Pol II Maor-Shoshani A2000 Overall Error Rate 0.00148 errors/bp
Eco Pol II Maor-Shoshani A2000 Overall Error Rate 0.00065 errors/bp

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