A novel chimeric peptide with antimicrobial activity

Abstract

Beta-lactamase-mediated bacterial drug resistance exacerbates the prognosis of infectious diseases, which are sometimes treated with co-administration of beta-lactam type antibiotics and beta-lactamase inhibitors. Antimicrobial peptides are promising broad-spectrum alternatives to conventional antibiotics in this era of evolving bacterial resistance. Peptides based on the Ala46-Tyr51 beta-hairpin loop of beta-lactamase inhibitory protein (BLIP) have been previously shown to inhibit beta-lactamase. Here, our goal was to modify this peptide for improved beta-lactamase inhibition and cellular uptake. Motivated by the cell-penetrating pVEC sequence, which includes a hydrophobic stretch at its N-terminus, our approach involved the addition of LLIIL residues to the inhibitory peptide N-terminus to facilitate uptake. Activity measurements of the peptide based on the 45-53 loop of BLIP for enhanced inhibition verified that the peptide was a competitive beta-lactamase inhibitor with a K(i) value of 58 μM. Incubation of beta-lactam-resistant cells with peptide decreased the number of viable cells, while it had no effect on beta-lactamase-free cells, indicating that this peptide had antimicrobial activity via beta-lactamase inhibition. To elucidate the molecular mechanism by which this peptide moves across the membrane, steered molecular dynamics simulations were carried out. We propose that addition of hydrophobic residues to the N-terminus of the peptide affords a promising strategy in the design of novel antimicrobial peptides not only against beta-lactamase but also for other intracellular targets.

Membrane Active Peptides and Their Biophysical Characterization

“…Using peptide conjugates for drug delivery into the cell has been a topic of interest and there are many anticancer [ 378 ], anti-inflammatory [ 379 ], and neurodegenerative [ 380 ] peptide conjugate drugs that are in clinical use or under investigation. Our group has also been focusing on combining the inhibitory properties of inhibitor peptides with CPPs [ 381 ]. Peptide vaccines (reviewed by Baig et al [ 382 ]) have also gained interest in the immunotherapy of different types of cancer [ 383 ] such as breast cancer [ 384 , 385 ] or lung cancer [ 386 ], virally mediated diseases such as influenza [ 387 ], Human papilloma virus (HPV) [ 388 , 389 ], and HIV, and neurodegenerative diseases [ 382 ] such as Alzheimer’s [ 390 ].…”

An evolutionarily conserved allosteric site modulates beta-lactamase activity

“…Unfortunately, many of the over 1300 different beta-lactamases can rapidly hydrolyze these inhibitors rendering them ineffective. In this context, continued search for novel inhibitors is an area of intense research 8,9 .…”

pVEC hydrophobic N‐terminus is critical for antibacterial activity

“…Previously, we showed that novel chimeric peptides, constructed by combining the N‐terminal residues of pVEC and beta‐lactamase inhibitory peptides, act as potential inhibitors that can move across the cell membrane . We also showed by SMD simulations that positively charged residues contribute to adsorption on the lipid bilayer via electrostatic interactions, while the N‐terminal truncated pVEC (del5 pVEC), I3A, L5A, R7A mutants, and scramble‐pVEC made weaker interactions with the lipids, highlighting the contribution of the N‐terminal residues and the relative position of the structural regions in the primary sequence to translocation .…”