Design of short membrane selective antimicrobial peptides containing tryptophan and arginine residues for improved activity, salt‐resistance, and biocompatibility

Abstract

Antimicrobial peptides (AMPs) kill microbes by non-specific membrane permeabilization, making them ideal templates for designing novel peptide-based antibiotics that can combat multi-drug resistant pathogens. For maximum efficacy in vivo and in vitro, AMPs must be biocompatible, salt-tolerant and possess broad-spectrum antimicrobial activity. These attributes can be obtained by rational design of peptides guided by good understanding of peptide structure-function. Toward this end, this study investigates the influence of charge and hydrophobicity on the activity of tryptophan and arginine rich decamer peptides engineered from a salt resistant human β-defensin-28 variant. Mechanistic investigations of the decamers with detergents mimicking the composition of bacterial and mammalian membrane, reveal a correlation between improved antibacterial activity and the increase in tryptophan and positive residue content, while keeping hemolysis low. The potent antimicrobial activity and high cell membrane selective behavior of the two most active decamers, D5 and D6, are attributed to an optimum peptide charge to hydrophobic ratio bestowed by systematic arginine and tryptophan substitution. D5 and D6 show surface localization behavior with binding constants of 1.86 × 10(8) and 2.6 × 10(8) M(-1) , respectively, as determined by isothermal calorimetry measurements. NMR derived structures of D5 and D6 in SDS detergent micelles revealed proximity of Trp and Arg residues in an extended structural scaffold. Such potential cation-π interactions may be critical in cell permeabilization of the AMPs. The fundamental characterization of the engineered decamers provided in this study improves the understanding of structure-activity relationship of short arginine tryptophan rich AMPs, which will pave the way for future de novo design of potent AMPs for therapeutic and biomedical applications.

Interaction of blood components with cathelicidins and their modified versions

“…Higher hydrophilicity of R3 might be the reason for its lower hemolytic activity even though it has +5 charge. Thus an optimal balance between the hydrophobicity and charges is crucial for achieving low MIC values and low toxicity in the case of new synthetic peptides, and the data is consistent with the current literature [13][14][15][16].…”

“…The most important factors used for the estimation of hemolytic activity has been proposed as net charge and hydrophobicity [13][14][15][16]. In our case, it seems that the hydrophobicity was correlated with the hemolytic activity than the overall charge of the peptide.…”

“…Optimum charge to hydrophobic ratio achieved by systematic substitution of arginine and tryptophan is necessary to maximize antimicrobial potency, while maintaining low cytotoxicity [16]. cAMPs have also shown to have impact on the blood coagulation and participate in the multiple aspects of immunity and trigger the immune system [17].…”

Anti-Mycobacterial Peptides: From Human to Phage

“…For maximum efficacy in vivo and in vitro , these attributes would need optimizing for an antimicrobial peptide. Some strategies have been used to generate peptides with improved antimicrobial activity, such as site-saturation mutagenesis [83], D-amino acids isomerization [84], synthetic modifications [85,86,87], De novo -design AMPs [87,88,89] and high-throughput screening [90,91]. These methods provide excellent ways for searching novel and efficient anti-mycobacterial peptides.…”

Membrane Active Peptides and Their Biophysical Characterization

“…Furthermore, ITC is a preferred approach for the analysis of CPPs that are coupled to larger biomolecules since CD and NMR spectra of these large molecules are very difficult to analyze [208] and unlike NMR techniques, ITC does not require large amounts of samples [209]. There are different applications of ITC to characterize the thermodynamic aspects of peptide-membrane interactions [205,[210][211][212][213][214].…”