Study of the role of PolIV in Pseudomonas aeruginosa lasR mutagenesis

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)

High prevalence of lasR-deficient Pseudomonas aeruginosaoccurring naturally in Cystic Fibrosis chronic lung infections hasbeen shown. However, mutational mechanisms acting on LasRinactivation remain poorly investigated. We previously linked theMismatch Repair System-deficiency with the emergence of lasRmutants, showing that lasR variants reproducibly emerge at a highfrequency from a hypermutator mutS strain. Here, we explored theinvolvement of transient hypermutability in lasR mutagenesis bystudying the role of the error-prone DNA polymerase PolIV (dinB).A dinB null mutant derived from a mutS strain was constructed andthe emergence of lasR variants was analyzed. Notably, dinBdisruption in a hypermutator background (mutSdinB) resulted in 3fold increase (P=0.04) in the lasR emergence frequency respect tothe mutS strain. Furthermore, over-expression of PolIV in themutSdinB strain resulted in 16 fold decrease (P=0.04) in lasRemergence. Analysis of the lasR mutational spectra in lasR variantsderived from the mutS strain, displayed that lasR inactivation wasentirely due to base substitutions (80% C-T transitions). In contrast,20% of lasR variants emerged from the mutSdinB strain contained -1frameshift and 80% base substitutions with only 38% being C-Ttransitions. These results suggest that Pol IV could play anantimutator role in lasR mutagenesis.