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A Computationally Designed Peptide Derived from Escherichia coli as a Potential Drug Template for Antibacterial and Antibiofilm Therapies

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journal contribution
posted on 22.10.2018, 00:00 by Marlon H. Cardoso, Elizabete S. Cândido, Lai Y. Chan, Marcelo Der Torossian Torres, Karen G. N. Oshiro, Samilla B. Rezende, William F. Porto, Timothy K. Lu, Cesar de la Fuente-Nunez, David J. Craik, Octávio L. Franco
Computer-aided screening of antimicrobial peptides (AMPs) is a promising approach for discovering novel therapies against multidrug-resistant bacterial infections. Here, we functionally and structurally characterized an Escherichia coli-derived AMP (EcDBS1R5) previously designed through pattern identification [α-helical set (KK­[ILV](3)[AILV])], followed by sequence optimization. EcDBS1R5 inhibited the growth of Gram-negative and Gram-positive, susceptible and resistant bacterial strains at low doses (2–32 μM), with no cytotoxicity observed against non-cancerous and cancerous cell lines in the concentration range analyzed (<100 μM). Furthermore, EcDBS1R5 (16 μM) acted on Pseudomonas aeruginosa pre-formed biofilms by compromising the viability of biofilm-constituting cells. The in vivo antibacterial potential of EcDBS1R5 was confirmed as the peptide reduced bacterial counts by two-logs 2 days post-infection using a skin scarification mouse model. Structurally, circular dichroism analysis revealed that EcDBS1R5 is unstructured in hydrophilic environments, but has strong helicity in 2,2,2-trifluoroethanol (TFE)/water mixtures (v/v) and sodium dodecyl sulfate (SDS) micelles. The TFE-induced nuclear magnetic resonance structure of EcDBS1R5 was determined and showed an amphipathic helical segment with flexible termini. Moreover, we observed that the amide protons for residues Met2-Ala8, Arg10, Ala13-Ala16, and Trp19 in EcDBS1R5 are protected from the solvent, as their temperature coefficients values are more positive than −4.6 ppb·K–1. In summary, this study reports a novel dual-antibacterial/antibiofilm α-helical peptide with therapeutic potential in vitro and in vivo against clinically relevant bacterial strains.