Antimicrobial Peptides: Classification, Design, Application and Research Progress in Multiple Fields

Abstract

Antimicrobial peptides (AMPs) are a class of small peptides that widely exist in nature and they are an important part of the innate immune system of different organisms. AMPs have a wide range of inhibitory effects against bacteria, fungi, parasites and viruses. The emergence of antibiotic-resistant microorganisms and the increasing of concerns about the use of antibiotics resulted in the development of AMPs, which have a good application prospect in medicine, food, animal husbandry, agriculture and aquaculture. This review introduces the progress of research on AMPs comprehensively and systematically, including their classification, mechanism of action, design methods, environmental factors affecting their activity, application status, prospects in various fields and problems to be solved. The research progress on antivirus peptides, especially anti-coronavirus (COVID-19) peptides, has been introduced given the COVID-19 pandemic worldwide in 2020.

Keywords: antimicrobial peptides; application; classification; coronavirus; design; mode of action; motifs.

FIGURE 1

Classification of antimicrobial peptides.

FIGURE 2

Statistics of the main functions of antimicrobial peptides. Antibacterial peptides account for the largest proportion, approximately 60%, followed by antifungal peptides, which account for 26%, and antiviral, antiparasitic, anticancer, anti-HIV peptides account for almost the same about 2–5% (the figure is drawn based on data in APD3).

FIGURE 3

Examples of specific targets for Antiviral peptides.

FIGURE 4

Information of COVID-19. (A) C-F13-nCoV Wuhan strain 02, Strain Number: CHPC 2020.00002; NPRC 2020.00002, Source: National Pathogen Resource Collection Center (National Institute for Viral Disease Control and Prevention under Chinese Center for Disease Control and Prevention). (B) Structure of novel coronavirus spike receptor-binding domain complexed with its receptor ACE2. (10.2210/pdb6LZG/pdb).

FIGURE 5

Different structures of AMPs. (A) LL-37 adopts a typical α-helical conformation (10.2210/pdb2K6O/pdb). (B) Gomesin is a β-sheet peptide and stabilized by disulfide bonds (10.2210/pdb1KFP/pdb). (C) Indolicidin is a AMP with linear extension structure instead of well-defined 3D structure (10.2210/pdb1G89/pdb). (D) α1-purothionin adopts both alpha-helix and beta-sheet conformation, and arrows indicate extension direction (10.2210/pdb2plh/pdb).

FIGURE 6

Models of action for extracellular AMP activity. (A) Carpet model: accumulation of AMPs on the surface and then destroy the cell membrane in the manner of “detergent”. (B) Barrel stave model: AMPs aggregate with each other and are inserted into the bilayer of the cell membrane in the form of multimers and arrange parallel to the phospholipids, then form a channel. (C) Toroidal pore model: accumulation of AMPs vertically embed in the cell membrane, and then, bend to form a ring hole.

FIGURE 7

Comparison of Gram-negative bacteria, Gram-positive bacteria and fungi cell walls.