C-terminal Lysine-Linked Magainin 2 with Increased Activity Against Multidrug-Resistant Bacteria

Abstract

Due to the growing problem of antibiotic-resistant microorganisms, the development of novel antimicrobial agents is a very important challenge. Dimerization of cationic antimicrobial peptides (cAMPs) is a potential strategy for enhancing antimicrobial activity. Here, we studied the effects of magainin 2 (MG2) dimerization on its structure and biological activity. Lysine and glutamic acid were used to synthesize the C- and N-terminal dimers of MG2, respectively, in order to evaluate the impact of linker position used to obtain the dimers. Both MG2 and its dimeric versions showed a random coil structure in aqueous solution. However, in the presence of a structure-inducing solvent or a membrane mimetic, all peptides acquired helical structure. N-terminal dimerization did not affect the biological activity of the peptide. On the other hand, the C-terminal dimer, (MG2)2K, showed antimicrobial activity 8-16 times higher than that of MG2, and the time required to kill Escherichia coli was lower. The enhanced antimicrobial activity was related to membrane permeabilization. (MG2)2K was also more active against multidrug-resistant bacteria of clinical origin. Overall, the results presented here demonstrate that C-terminal lysine-linked dimerization improve the activity of MG2, and (MG2)2K can be considered as a potential antimicrobial agent.

The Mechanisms of Action of Cationic Antimicrobial Peptides Refined by Novel Concepts from Biophysical Investigations

“…These findings are in line with increased membrane-perturbing properties of larger peptide aggregates (illustrated in Fig. 4.6ac) (Dempsey et al 2003;Lorenzon et al 2016;Verly et al 2017).…”

“…In combination with magainin monomers, the dimer stabilizes the pore formation in egg-PG membranes (Hara et al 2001). Notably whereas a dimer linked through a carboxy-terminal lysine extension was consider-ably more active than the monomer, the aminoterminal linkage through glutamic acid has no effect (Lorenzon et al 2016).…”

The “pre-assembled state” of magainin 2 lysine-linked dimer determines its enhanced antimicrobial activity

“…MG2 is one of the first AMP described [9] and might be the most studied, whose bactericidal activity arises from leakage of cell contents via pores formed by the peptides [37][38][39]. Attempts to increase antimicrobial activity have been made with MG2 analogues [40][41][42][43], especially dimers [24,44,45]. The dimeric peptide (MG2) 2 K with a lysine residue as a linker, for instance, showed the highest antimicrobial activity among disulfide linked analogues, with faster killing of E. coli and 16-fold decrease in the minimum inhibitory concentration (MIC) [24].…”

“…In a recent study, we showed that C-terminal dimerization of MG2 affects considerably its antimicrobial activity. The dimeric version (MG2) 2 K was up to 16 times more efficient than MG2 to kill Escherichia coli, and required a fourth of the time of the monomer to exert its antimicrobial activity [24].…”

Efeitos da dimerização e modificações na porção N-terminal do peptídeo antimicrobiano Aureína 1.2 em sua interação com filmes de Langmuir e atividade biológica

“…Sendo a oligomerização um pré-requisito para a atividade dos PAMs, a ligação de duas moléculas para formar dímeros tem sido alvo de estudos recentes. Em alguns casos, a dimerização leva a moléculas mais ativas (47). No entanto, os efeitos desta alteração na atividade dos PAMs ainda são pouco compreendidos, pois algumas versões diméricas apresentaram redução de atividade antimicrobiana ou aumento de toxicidade.…”