Unraveling the link between adaptive evolution and hypermutability in Pseudomonas aeruginosa populations?

SMANIA AM

Mar del Plata

Simposio; LI Reunión Anual de La Sociedad Argentina de Bioqu{imica y Biolog{ia Molecular (SAIB); 2015

Pseudomonas aeruginosa is a remarkable versatile bacterial species that proliferates in diverse habitats, including thehuman body. It constitutes an important opportunistic pathogen, being the main cause of chronic airway infectionsand mortality in cystic fibrosis patients (CF). We are currently focused on understanding the molecular basisunderlying its adaptive capability. In this sense, we have long studied the systems by which cells can increase themutation rate and acquire hypermutator states. Our main interest is to decipher the role of hypermutability in theoccurrence of particular phenotypic switches related to chronic airway infections, as well as in more complexprocesses such as biofilm formation. In the last years, we unravelled the way in which the combined activities of themismatch 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 anincreased competitiveness. By carrying out a genomic approach we revealed the genetic evolution of mutators duringthe course of CF chronic infection, which showed an extensive within-patient diversification and populationsstructured in different coexisting subpopulations.