Role of PolIV, ImuB and DnaE2 DNA polymerases in Pseudomonas aeruginosa stress-induced mutagenesis

FELIZIANI, SOFIA; LUJAN, ADELA M; MOYANO, ALEJANDRO J; SMANIA, ANDREA M

Tucuman

Congreso; 45 Annual Meeting Argentine Society for Biochemistry and Molecular Biology; 2009

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB)

Here, we studied the role of PolIV, ImuB and DnaE2 inPseudomonas aeruginosa (PA) stress-induced mutagenesis. Weconstructed PAO1 dinB, imuB and dnaE2 mutants and analyzedtheir role in UV-induced mutagenesis. After UV irradiation, PAO1showed a 2.6 fold increase (P=0.038) in the mutation frequencyconfirming that PA displays a subtle UV-induced mutatorphenotype. PolIV deficiency resulted in levels of UV-inducedmutagenesis similar to the wild type strain (ratio 3.6; P=0.019). Incontrast, imuB (ratio 0.83, P=0.09) and dnaE2 (ratio 0.72, P=0.2)showed no increase in the mutation frequencies after induction,indicating that UV-induced mutagenesis in PA might depend onImuB and DnaE2 but not on PolIV. We further investigated the roleof these DNA polymerases in stationary-phase mutagenesis using aplasmid-based test system that allows the detection of -1 deletionsand substitutions. These plasmids contain the reporter gene pheAharboring loss-of-function mutations that produce phenolmonooxygenase inactivation, but whose reversion allows bacteriato grow using phenol as the sole carbon source. Results obtainedfrom the incubation of PAO1 carrying the plasmids on phenolselective plates showed that PA displays stationary-phasemutagenesis. We are currently analyizing dinB, imuB and dnaE2strains in order to study the role of these DNA polymerases instationary-phase mutagenesis.