Prediction and bioactivity of small-molecule antimicrobial peptides from Protaetia brevitarsis Lewis larvae

Abstract

Antimicrobial peptides (AMPs) are widely recognized as promising natural antimicrobial agents. Insects, as the group of animals with the largest population, have great potential as a source of AMPs. Thus, it is worthwhile to investigate potential novel AMPs from Protaetia brevitarsis Lewis larvae, which is a saprophagous pest prevalent in China. In this study, comparing the whole-genome sequence of Protaetia brevitarsis Lewis larvae with the Antimicrobial Peptide Database (APD3) led to the identification of nine peptide templates that were potentially AMPs. Next, based on the peptide templates, 16 truncated sequences were predicted to the AMPs by bioinformatics software and then underwent structural and physicochemical property analysis. Thereafter, candidate small-molecule AMPs were artificially synthesized and their minimal inhibitory concentration (MIC) values were assessed. A candidate peptide, designated FD10, exhibited strong antimicrobial activity against both bacteria and fungi comprising Escherichia coli (MIC: 8 μg/mL), Pseudomonas aeruginosa (MIC: 8 μg/mL), Bacillus thuringiensis (MIC: 8 μg/mL), Staphylococcus aureus (MIC: 16 μg/mL), and Candida albicans (MIC: 16 μg/mL). Additionally, two other candidate peptides, designated FD12 and FD15, exhibited antimicrobial activity against both E. coli (MIC: both 32 μg/mL) and S. aureus (MIC: both 16 μg/mL). Moreover, FD10, FD12, and FD15 killed almost all E. coli and S. aureus cells within 1 h, and the hemolytic effect of FD10 (0.31%) and FD12 (0.40%) was lower than that of ampicillin (0.52%). These findings indicate that FD12, FD15, and especially FD10 are promising AMPs for therapeutic application. This study promoted the development of antibacterial drugs and provided a theoretical basis for promoting the practical application of antimicrobial peptides in the Protaetia brevitarsis Lewis larvae.

Jelleine, a Family of Peptides Isolated from the Royal Jelly of the Honey Bees (Apis mellifera), as a Promising Prototype for New Medicines: A Narrative Review

“…Currently, five different membrane-target models are considered to explain the mode of action of AMPs on biological membranes [ 64 , 65 ]: (i) the Barrel-stave model, in which the peptide monomers associate and form a bundle of helices embedded in the membrane, forming a transmembrane channel [ 66 ]; (ii) the toroidal pore model (also called wormhole), in which the amphipathic peptide interacts electrostatically with the phospholipid–plasma membrane in a perpendicular orientation relative to the membrane bilayer. In this way, the peptide exerts pressure on the membrane and separates the polar heads elements of phospholipids, resulting in the upper lipid monolayer curving bend through the pore in such a way that the pore lumen consists of peptide molecules and polar heads of phospholipids mixed together [ 66 ]; (iii) the carpet-like model, in which the AMP accumulates on the surface of the plasmatic membrane due to the electrostatic interaction between the positively charged peptide residues and the negative charges of phospholipids, covering it similarly to a carpet, which lead to membrane permeabilisation [ 65 , 66 ]; (iv) the aggregate channel model, which assumes that a supramolecular peptide–lipid complex is formed that mediates the mutually coupled trans-bilayer transport of lipid and peptides, implicitly assuming that informal aqueous channels exist within these aggregates, allowing the free passage of ions and possibly larger molecules [ 64 , 67 ]; and (v) the detergent-like model, in which AMPs aggregates in the membrane surface and after reach a critical concentration promote a micellisation process in the phospholipid bilayer [ 65 ]. Molecular dynamics simulations showed that jelleine-I acts by increasing the pressure on the lipid bilayer of the bacterial membrane [ 50 ].…”

Capping motifs in antimicrobial peptides and their relevance for improved biological activities

“…The importance of helical structure allows AMPs to be continuously exploited for potential individual use or in combination with established antibiotics, especially in the new era of treating multidrug resistant bacteria affecting both human and animal health ( Lei et al, 2019 ; Fu et al, 2023 ). Highlighting their advantages, AMPs offer a slower emergence of resistance, rapid lethal action, and effective control of biofilms, positioning them as optimal candidates for treatment of drug-resistant pathogens ( Magana et al, 2020 ).…”

Comparative Analysis of Hindgut Microbiota Variation in Protaetia brevitarsis Larvae across Diverse Farms

“…The most abundant fatty acid, oleic acid, accounts for more than 58% of the total fatty acids [ 9 , 11 ]. Although nutritional and functional chemical composition can be changed in response to feed materials and supplementary feeds [ 6 , 10 , 11 ], P. brevitarsis larvae also have a broad range of pharmacological activities, including anti-obesity and anti-diabetic effects [ 12 , 13 ], therapeutic effects on prostatic hyperplasia [ 14 ], the inhibition of osteoclastogenesis [ 15 ], neuroprotective effects against seizures and neurodegeneration [ 16 ], anti-bacterial and anti-inflammatory activities [ 17 , 18 ], and an anti-thrombotic function [ 19 ].…”