Paulina Jęcz

Interactions between parS(/i), centromere-like sequences, and their cognate protein ParB in Pseudomonas aeruginosa PAO1161

Paulina Jęcz, IBB PAS ,
Supervisors: prof. Grażyna Jagura-Burdzy, IBB PAS

Pseudomonas aeruginosa is an opportunistic pathogen causing fatal nosocomial infections in immunocompromised patients. The currently available antibiotic treatments are ineffective due to the intrinsic multidrug resistance of P. aeruginosa strains. The research is focused on the crucial biological processes as possible targets of antibacterial therapy. One of the mechanisms of P. aeruginosa chromosome segregation is its partitioning system comprising of three players: ParA protein, Walker-type ATPase, DNA binding protein ParB and ten cis-acting parS (centromere-like) sequences.
The aim of our study is to establish the role of multiple parSs scattered around the genome and dissect the ParB- parS interactions. The particular mutated parS sequences have been introduced into P. aeruginosa chromosome by reverse genetics thus the collection of mutants deprived of single or multiple parS sequences has been obtained. The mutants analysis based on the growth characteristics, motility assays, nucleoid condensation/ number of anucleate cells (DAPI staining) and ParB localization (FITC assay) was combined with the transcriptome analysis by use of microarrays. The preliminary results suggest that only modifications of all 10 parS binding sites (parSnull mutant) lead to the defects observed previously in parA and parB deletion mutants. The presence of the single parS sequence in the genome is sufficient for correct chromosome segregation in P. aeruginosa although even mutated one out of ten parS sequences has a strong regulatory effect on gene expression.

Discussion