A computationally designed peptide derived from Escherichia colias a potential drug template for antibacterial and antibiofilm therapies
Marlon Cardoso, Elizabete Cândido, Lai Chan, Marcelo Der Torossian Torres, Karen Oshiro, Samilla Rezende, William F Porto, Timothy K. Lu, Cesar de la Fuente-Nunez, David J Craik, Octávio L. Franco
ACS Infectious Diseases
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 to 32 μM), with no cytotoxicity observed against non-cancerous and cancerous cell lines in the concentration range analysed (<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 two 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 sulphate (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 Try19 in EcDBS1R5 are protected from the solvent, as their temperature coefficients values are more positive than -4.6 ppb.k-1, thus indicating intrapeptide hydrogen bonding interactions. 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.
Circular dichroism, Secondary structure, Chemical stability, Biochemistry