Mesobuthus Venom-Derived Antimicrobial Peptides Possess Intrinsic Multifunctionality and Differential Potential as Drugs

Abstract

Animal venoms are a mixture of peptides and proteins that serve two basic biological functions: predation and defense against both predators and microbes. Antimicrobial peptides (AMPs) are a common component extensively present in various scorpion venoms (herein abbreviated as svAMPs). However, their roles in predation and defense against predators and potential as drugs are poorly understood. Here, we report five new venom peptides with antimicrobial activity from two Mesobuthus scorpion species. These α-helical linear peptides displayed highly bactericidal activity toward all the Gram-positive bacteria used here but differential activity against Gram-negative bacteria and fungi. In addition to the antibiotic activity, these AMPs displayed lethality to houseflies and hemotoxin-like toxicity on mice by causing hemolysis, tissue damage and inducing inflammatory pain. Unlike AMPs from other origins, these venom-derived AMPs seem to be unsuitable as anti-infective drugs due to their high hemolysis and low serum stability. However, MeuTXKβ1, a known two-domain Mesobuthus AMP, is an exception since it exhibits high activity toward antibiotic resistant Staphylococci clinical isolates with low hemolysis and high serum stability. The findings that the classical AMPs play predatory and defensive roles indicate that the multifunctionality of scorpion venom components is an intrinsic feature likely evolved by natural selection from microbes, prey and predators of scorpions. This definitely provides an excellent system in which one can study how a protein adaptively evolves novel functions in a new environment. Meantimes, new strategies are needed to remove the toxicity of svAMPs on eukaryotic cells when they are used as leads for anti-infective drugs.

In-Depth In Silico Search for Cuttlefish (Sepia officinalis) Antimicrobial Peptides Following Bacterial Challenge of Haemocytes

“…GK28 inhibited the growth of V. alginolyticus, V. splendidus and V. parahaemolyticus equally as the positive control oxytetracycline did at concentrations ≤5 µM and was also equally bactericidal against V. splendidus. In contrast to marmelittin-its closest homologue active against a broad range of Gram-negative and Gram-positive bacteria [68]-GK28 seemed only active against Gram-negative bacteria. GK28 was the only peptide active against a non-Vibrio species, i.e., E. coli.…”

“…Finally, NF19 was the most haemolytic peptide: it induced 35 and 50% haemolysis at 50 and 100 µM, respectively. The most active peptide-GK28-was not haemolytic at any concentration whereas its closest homologue marmelittin is highly haemolytic on mouse, bird and lizard erythrocytes [68].…”

“…AV19 possessed 40% similarity with two frog antibacterial peptides, namely temporin-1Cd from Rana clamitans [66] and temporin-1Ola from R. akaloosae [67]. GK28 possessed 35.48% similarity with marmelittin from the venom of the scorpion Mesobuthus eupeus [68] and a C-terminal end similar to the one of GR21 [35], in addition to the lowest hydrophobic ratio and the highest net charge of the selected peptides. Both NF19 and II19 possessed similarity with AMPs from the bovine rumen microbiome-47.36% with P20 and 41.66% with lynronne-2, respectively [69].…”

Development of chimeric peptides to facilitate the neutralisation of lipopolysaccharides during bactericidal targeting of multidrug-resistant Escherichia coli

“…The thermal, pH and enzyme stability of A6 and G6 were evaluated against MDR E. coli CVCC195 using a previous method with minor revisions 25 . The N6, A6, and G6 solutions were treated at different temperatures (20-100°C) for 1 h, dissolved and incubated at different pH values (2-10) for 3 h, or incubated with trypsin or pepsin for 4 h. The inhibition zone diameters were measured after incubation at 37°C for 18-24 h. The peptides were dissolved in H 2 O or mice serum at 37°C to detect their serum stability and samples were removed at different time points to determine their residual activity by the inhibition zone or reverse-phase high-performance liquid chromatography (RP-HPLC) methods 62,63 .…”

Loop Replacement Enhances the Ancestral Antibacterial Function of a Bifunctional Scorpion Toxin

“…Because the whole loop sequence of MeuTXKα3 was substituted by that of the defensin, we conjecture that it may be deficient in K + channel blockade, although this needs to be further investigated. Apart from MeuTXKα3, there exists another group of peptides with dual activities—including cytolytic/antimicrobial activity and the blocking of K + channels in scorpion venom—called β-SPN peptides [ 28 , 29 , 30 , 31 ]. Compared with α-KTxs, these peptides evolved an extended N-terminal α-helical domain, which is closely related to their antibacterial activity.…”