Peptide inhibitors of the essential cell division protein FtsA

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Abstract
The revolutionary era of antibiotics has been overwhelmed by the evolutionary capacity of microorganisms such as Pseudomonas aeruginosa to develop resistance to all classes of antibiotics. In the perspective of identifying new antimicrobials using novel strategies, we targeted the essential and highly conserved FtsA protein from the bacterial cell division machinery of P.aeruginosa. In a series of experiments we cloned, overproduced and purified the FtsA and FtsZ proteins. Expression of FtsA into Escherichia coli cells led to its accumulation in inclusion bodies. We developed a protocol permitting the purification and refolding of enzymatically active FtsA hydrolysing ATP. The purified enzyme was used to screen for peptide inhibitors of ATPase activity using phage display. Selective biopanning assays were done and phages were eluted using ATP, a non-hydrolysable ATP analogue and the protein FtsZ known to interact with FtsA in the divisome during the process of bacterial cell division. We identified two consensus peptide sequences interacting with FtsA and a competitive ELISA was used to identify peptides having high affinity for the target protein. Five of the six peptides synthesized showed specific inhibition of ATPase activity of FtsA with IC50 values between 0.7 and 35 mM. Discovery of peptides inhibiting the essential cell division machinery in bacteria is the first step for the future development of antimicrobial agents via peptidomimetism.