Surface evaluation techniques to characterize ?de novo? design antimicrobial peptides

MATURANA, PATRICIA; MARTÍNEZ, MELINA ; SEMORILE, LILIANA; MAFFIA, PAULO; HOLLMANN, AXEL

Cuidad Autónoma de Buenos Aires

Congreso; II Reunión Conjunta de Sociedades de BioCiencias; 2017

Conventional antibiotics are facing strong microbial resistancethat has recently reached critical levels. This situation is leading toa reduced therapeutic potential of a huge proportion of antimicrobialagents currently used in the clinic. Antimicrobial peptides (AMPs)could provide the medical community with an alternative strategy totraditional antibiotics for combating microbial resistance. However,fully understand their mechanisms of action and promote the reductionof the unwanted toxicity remains as a critical step to considerthese compounds to be a therapeutic promise and overcome clinicalsetbacks. In this context, this work focused on unravel the way ofaction of de novo designed AMPs by using surface evaluation techniquesas Surface Pressure, Surface Plasmon Resonance (SPR)and Atomic Force Microscopy (AFM). Surface pressure results obtainedwell correlate the highest affinity toward negatively chargedmembranes with the lowest CIM values. Whereas SPR techniquethat allows to obtain association (ka) and dissociation (kd) constantsand calculate the fraction of the peptide that remains bound to thelipid membranes after dissociation (Rb), allows to dissect the kindof interactions. SPR results showed that beside the importance of ahigh membrane affinity, that allow the peptides reach the membrane,this Rb parameter complements the analysis and helps to clarifymisinterpretations of the Kd data, confirming that Is also importantthat peptides remained strongly bound to membranes (i.e. high Rb) Finally, by AFM we were able to visualize the effects of AMPs directlyon the bacterial cells. Error and height images showed that after1h of peptide incubation, bacteria surface was severely damagedand leakage of intracellular media was also observed.Overall, our studies focus on understanding possible relationsbetween AMP?membrane interactions and the efficiency of thesedrugs, offering a rational basis for the improvement of these compounds.