Involvement of error-prone DNA polymerase IV in stationary-phase mutagenesis in Pseudomonas putida.
In this work we studied involvement of DNA polymerase IV (Pol IV) (encoded by the dinB gene) in stationary-phase mutagenesis in Pseudomonas putida. For this purpose we constructed a novel set of assay systems that allowed detection of different types of mutations (e.g., 1-bp deletions and different base substitutions) separately. A significant effect of Pol IV became apparent when the frequency of accumulation of 1-bp deletion mutations was compared in the P. putida wild-type strain and its Pol IV-defective dinB knockout derivative. Pol IV-dependent mutagenesis caused a remarkable increase (approximately 10-fold) in the frequency of accumulation of 1-bp deletion mutations on selective plates in wild-type P. putida populations starved for more than 1 week. No effect of Pol IV on the frequency of accumulation of base substitution mutations in starving P. putida cells was observed. The occurrence of 1-bp deletions in P. putida cells did not require a functional RecA protein. RecA independence of Pol IV-associated mutagenesis was also supported by data showing that transcription from the promoter of the P. putida dinB gene was not significantly influenced by the DNA damage-inducing agent mitomycin C. Therefore, we hypothesize that mechanisms different from the classical RecA-dependent SOS response could elevate Pol IV-dependent mutagenesis in starving P. putida cells.
Tegova
Radi
R
Department of Genetics, Institute of Molecular and Cell Biology, Tartu University and Estonian Biocentre, 23 Riia Street, 51010 Tartu, Estonia.
Tover
Andres
A
Tarassova
Kairi
K
Tark
Mariliis
M
Kivisaar
Maia
M
D020137:Base Pair Mismatch; D001483:Base Sequence; D019951:DNA Polymerase beta / Q000502:physiology*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D016958:Pseudomonas putida / Q000235:genetics*; D011938:Rec A Recombinases / Q000378:metabolism; D013014:SOS Response, Genetics; D014158:Transcription, Genetic
D011938:Rec A Recombinases; D019951:DNA Polymerase beta