The spectrum of acridine resistant mutants of bacteriophage T4 reveals cryptic effects of the tsL141 DNA polymerase allele on spontaneous mutagenesis.

Genetics (1998), Volume 148, Page 1655


Mutations in the ac gene of bacteriophage T4 confer resistance to acridine-inhibition of phage development. Previous studies had localized the ac gene region; we show that inactivation of T4 Open Reading Frame 52.2 confers the Acr phenotype. Thus, 52.2 is ac. The resistance mechanism is unknown. The ac gene provides a convenient forward mutagenesis assay. Its compact size (156 bp) simplifies mutant sequencing and diverse mutant types are found: base substitutions leading to missense or nonsense codons, in-frame deletions or duplications within the coding sequence, deletion or duplication frameshifts, insertions, complex mutations, and large deletions extending into neighboring sequences. Comparisons of spontaneous mutagenesis between phages bearing the wild-type or tsL141 alleles of DNA polymerase demonstrate that the impact of the mutant polymerase is cryptic when total spontaneous mutant frequencies are compared, but the DNA sequences of the ac mutants reveal a substantial alteration of fidelity by the mutant polymerase. The patterns of base substitution mutagenesis suggest that some site-specific mutation rate effects may reflect hotspots for mutagenesis arising by different mechanisms. A new class of spontaneous duplication mutations, having sequences inconsistent with misaligned pairing models, but consistent with nick-processing errors, has been identified at a hotspot in ac.



Fidelity, Mutational Analysis, Methods

One line summary:

Wild type and antimutator T4 DNA polymerases display similar mutation frequencies for resistance to acriflavin but the types of mutations made are different. This paper describes a forward mutation assay.


new topics/pols set partial results complete validated


Polymerase Reference Property Result Context
T4 A737V Wang FJ1998 Overall Error Rate 1 Mutation frequency (relative to WT) Technique: Sequencing

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