UNRAVELLING THE LINKAGE BETWEEN ADAPTIVE EVOLUTION AND HYPERMUTABILITY IN Pseudomonas aeruginosa

SMANIA AM

Mar del Plata

Simposio; LI Reunión Anual de la Sociedad Argentina de Bioquímica y Biología Molecular; 2015

Pseudomonas aeruginosa is a remarkable versatile bacterial species that proliferates in diverse habitats, including the human body. It constitutes an important opportunistic pathogen, being the main cause of chronic airway infections and mortality in cystic fibrosis patients (CF). We are currently focused on understanding the molecular basis underlying its adaptive capability. In this sense, we have long studied the systems by which cells can increase the mutation rate and acquire hypermutator states. Our main interest is to decipher the role of hypermutability in the occurrence of particular phenotypic switches related to chronic airway infections, as well as in more complex processes such as biofilm formation. In the last years, we unravelled the way in which the combined activities of the mismatch repair protein MutS with the error-prone DNA polymerase IV (Pol IV) and DNA simple sequence repeats (SSRs) can drive the mutagenesis of genes underlying specific adaptive processes. Moreover, we observed that P. aeruginosa mutators exhibit an enhanced morphotypical diversification in biofilms which correlates with an increased competitiveness. By carrying out a genomic approach we revealed the genetic evolution of mutators during the course of CF chronic infection, which showed an extensive within-patient diversification and populations structured in different coexisting subpopulations.