Présentation sous forme d’affiche au congrès CSM (Canadian Society of Microbiology) à Laval le 26 mai 2003.

Paradis-Bleau, C., Boudreault, L., Zoeiby, A., Sanschagrin, F., and Levesque, R.C. 2003. Identification of peptide inhibitors of the Pseudomonas aeruginosa FtsZ GTPase activity using phage display. 53rd Annual Meeting of the Canadian Society for Microbiologists, Laval, Quebec. May 25 to 28, 2003.

The opportunistic pathogen Pseudomonas aeruginosa frequently infects cystic fibrosis patients and immuno-compromised individuals. The acute resistance of P. aeruginosa to most classes of antibiotics lowers the efficacy of treatment. We are using the bacterial cell division machinery as a tool to identify new antimicrobial agents. The essential and highly conserved protein FtsZ from P. aeruginosa was used to screen for GTPase peptide inhibitors with the phage display technique. We used a C-7-C and a 12-mer libraries containing 109 different peptide fusions. The specificity of the screening was done by 3 rounds of biopanning and each round specificity was raised by increasing the stringency of the wash and by decreasing the time of contact between the phage and FtsZ. A competitive elution was done with 1 mM GTP and 5’-guanylylimidodiphosphate (a non-hydrolysable analogue of GTP). Peptides were isolated as phages and DNA of 20 phages per screening were sequenced. We identified 3 interesting consensus peptides witch could be GTPase peptide inhibitors of FtsZ. The specificity of the interaction between each peptide and FtsZ was analysed by ELISA. FtsZ was coated in a microplate well and the phage clone containing the corresponding peptide fusion was added. Biotinylated anti-fd rabbit polyclonal antibodies, HRP-streptavidine and its substrate ABTS were used to estimate protein-protein interaction. The 3 promising peptides have been synthesized and were tested on the GTPase activity of FtsZ. The inhibition of FtsZ represents a crucial target because the constriction of the Z-ring is the most important step in prokaryotic cell division. The phage display technique was helpful in the discovery of new promising peptides for the development of new antimicrobial agents.