Antimicrobial Proteins: Structure, Molecular Action, and Therapeutic Potential

Abstract

Second- and third-line treatments of patients with antibiotic-resistant infections can have serious side effects, such as organ failure with prolonged care and recovery. As clinical practices such as cancer therapies, chronic disease treatment, and organ transplantation rely on the ability of available antibiotics to fight infection, the increased resistance of microbial pathogens presents a multifaceted, serious public health concern worldwide. The pipeline of traditional antibiotics is exhausted and unable to overcome the continuously developing multi-drug resistance. To that end, the widely observed limitation of clinically utilized antibiotics has prompted researchers to find a clinically relevant alternate antimicrobial strategy. In recent decades, the discovery of antimicrobial peptides (AMPs) as an excellent candidate to overcome antibiotic resistance has received further attention, particularly from scientists, health professionals, and the pharmaceutical industry. Effective AMPs are characterized by a broad spectrum of antimicrobial activities, high pathogen specificity, and low toxicity. In addition to their antimicrobial activity, AMPs have been found to be involved in a variety of biological functions, including immune regulation, angiogenesis, wound healing, and antitumor activity. This review provides a current overview of the structure, molecular action, and therapeutic potential of AMPs.

Characteristics of antimicrobial peptide OaBac5mini and its bactericidal mechanism against Escherichia coli

“…The inner membrane integrity of E. coli ATCC 25922 was investigated by detecting the fluorescence changes of DiSC 3 (5). As shown in Figure 6C, the fluorescence intensity increased when bacteria were treated with OaBac5mini for 10 min, and gradually leveled off for the next 20 min.…”

“…The integrity of the inner membrane of E. coli ATCC 25922 treated by OaBac5mini was investigated by 3,3 ′ -Dipropylthiadicarbocyanine iodide [DiSC 3 (5), Sigma, USA], which is a fluorescent probe that can be concentrated in the integrated cytoplasmic membrane, leading to fluorescence selfquenching. If the membrane is depolarized or disrupted, DiSC 3 (5) is released into the aqueous medium and leads to increased fluorescence. The DiSC 3 (5) assay was conducted following the instruction of Sautrey et al (26) with minor modifications.…”

“…In brief, E. coli ATCC 25922 was centrifuged and diluted with 5 mM HEPES (containing 5 mM glucose) till OD 600 is 0.05. 1 µM DiSC 3 (5) was added into the prepared bacteria solution, then incubated at 37 • C with shaking at 220 rpm for 1 h in the dark. KCl solution was added (final concentration was 100 mM) after 30 min incubation.…”

“…Antimicrobial peptides (AMPs) are small molecular peptides in living organisms and serve as natural barriers against the invasion of pathogenic microorganisms (5). They are often referred to as cationic host defense peptides (HDPs) or cationic antimicrobial peptides (CAMPs) (6).…”

Effects of Dimerization, Dendrimerization, and Chirality in p-BthTX-I Peptide Analogs on the Antibacterial Activity and Enzymatic Inhibition of the SARS-CoV-2 PLpro Protein

“…AMPs are promising novel antibiotics that kill multidrug-resistant bacteria and show activity against some bacteria that are considered a priority by the WHO [ 5 ]. Their sequence normally has from 10 to 50 amino acids and is modulated by structure–function relationships [ 6 ]. The charge, amphipathicity, hydrophobicity and helicity of peptides are fundamental to their biological activity [ 7 ].…”