ROLE OF RadA FACTOR IN THE GENETIC RECOMBINATION OF Pseudomonas aeruginosa

MORO CAMILA; BORGOGNO MARÍA V; MONTI MARIELA R; ARGARAÑA CARLOS E

Congreso; LIV Reunión Anual de SAIB; 2018

Geneticrecombination in bacteria plays an important role in the repair of chromosomalDNA breaks and is one of the causes of resistance to the clastogenic effectproduced by some antibiotics. We have analyzed DNA recombination mechanisms inthe human opportunistic pathogen Pseudomonas aeruginosa, and found thecoexistence of both RecA dependent and independent pathways in this species. Inorder to determine the factors that mediate these mechanisms, we selected anumber of genes encoding proteins with known/suspected involvement in recombination,including the radA gene whose Archaea and E. coli homologues encode arecombinase and a helicase, respectively. Using a genetic system previouslydeveloped in our laboratory, we determined in vivo recombination rates forseveral mutant strains. In particular, a radA mutant showed recombination ratesas low as that observed in recA mutants (200-fold decrease compared to the WTstrain). Also, analysis of the b-galactosidasereporter present in our genetic system indicated that the loss of enzymeactivity (mutagenesis) previously detected in recombinant clones of WT andother strains is not observed in RadA deficient cells. Lastly, we found thatthe radA strain showed higher levels of cisplatin sensitivity than the WTstrain, consistent with the recombination rates measured for this strain. Inconclusion, we report here results indicate that RadA plays a key role in therecombination mechanisms of P. aeruginosa, not previously described. We arecurrently studying the in vitro activity of RadA; as well as its interplay withthe main recombination player, the RecA recombinase.