Role of RadA factor in the genetic recombination of Pseudomonas aeruginosa

Paraná, Entre Ríos

Congreso; LIV Reunión Anual de SAIB; 2018

Genetic recombination in bacteria plays an important role in the repair of chromosomal DNA breaks and is one of the causes of resistance to the clastogenic effect produced by some antibiotics. We have analyzed DNA recombination mechanisms in the human opportunistic pathogenPseudomonas aeruginosa, and found the coexistence of both RecA dependent and independent pathways in this species. In order to determine the factors that mediate these mechanisms, we selected a number of genes encoding proteins with known/suspected involvement in recombination, including theradAgene whoseArchaeaandE. colihomologues encode a recombinase and a helicase, respectively. Using a genetic system previously developed in our laboratory, we determined in vivo recombination rates for several mutant strains. In particular, aradAmutant showed recombination rates as low as that observed inrecAmutants (200-fold decrease compared to the WT strain). Also, analysis of the β-galactosidase reporter present in our genetic system indicated that the loss of enzyme activity (mutagenesis) previously detected in recombinant clones of WT and other strains is not observed in RadA deficient cells. Lastly, we found that the radA strain showed higher levels of cisplatin sensitivity than the WT strain, consistent with the recombination rates measured for this strain. In conclusion, we report here results indicate that RadA plays a key role in the recombination mechanisms of P. aeruginosa, not previously described. We are currently studying the in vitro activity of RadA; as well as its interplay with the main recombination player, the RecA recombinase.