Hp1090

Arthropod antimicrobial peptides (AMPs) offer a promising source of new leads to address the declining number of novel antibiotics and the increasing prevalence of multidrug-resistant bacterial pathogens. AMPs with potent activity against Gram-negative bacteria and distinct modes of action have been identified in insects and scorpions, allowing the discovery of AMP combinations with additive and/or synergistic effects. Here, we tested the synergistic activity of two AMPs, from the dung beetle Copris tripartitus (CopA3) and the scorpion Heterometrus petersii (Hp1090), against two strains of Escherichia coli. We also tested the antibacterial activity of two hybrid peptides generated by joining CopA3 and Hp1090 with linkers comprising two (InSco2) or six (InSco6) glycine residues. We found that CopA3 and Hp1090 acted synergistically against both bacterial strains, and the hybrid peptide InSco2 showed more potent bactericidal activity than the parental AMPs or InSco6. Molecular dynamics simulations revealed that the short linker stabilizes an N-terminal 310-helix in the hybrid peptide InSco2. This secondary structure forms from a coil region that interacts with phosphatidylethanolamine in the membrane bilayer model. The highest concentration of the hybrid peptides used in this study was associated with stronger hemolytic activity than equivalent concentrations of the parental AMPs. As observed for CopA3, the increasing concentration of InSco2 was also cytotoxic to BHK-21 cells. We conclude that AMP hybrids linked by glycine spacers display potent antibacterial activity and that the cytotoxic activity can be modulated by adjusting the nature of the linker peptide, thus offering a strategy to produce hybrid peptides as safe replacements or adjuncts for conventional antibiotic therapy.

The spike protein of SARS-CoV-2 (Severe Acute Respiratory Syndrome coronavirus 2) interacts with the ACE2 receptor in human cells and starts the infection of COVID-19 disease. Given the importance of spike protein's interaction with ACE2 receptor, we selected some antiviral peptides of venom scorpion such as HP1090, meucin-13, and meucin-18 and performed docking and molecular docking analysis of them with the RBD domain of spike protein. The results showed that meucin-18 (FFGHLFKLATKIIPSLFQ) had better interaction with the RBD domain of spike protein than other peptides. We also designed some mutations in meucin-18 and investigated their interactions with the RBD domain. The results revealed that the A9T mutation had more effective interaction with the RBD domain than the meucin-18 and was able to inhibit spike protein's interaction with ACE2 receptor. Hence, peptide "FFGHLFKLTTKIIPSLFQ" can be considered as the potential drug for the treatment of COVID-19 disease.

Hepatitis C virus (HCV) is a major cause of chronic liver disease, cirrhosis, and hepatocellular carcinoma. There is no vaccine available for HCV, and almost half of patients cannot be cured using standard combination therapy. Thus, new anti-HCV strategies and drugs are urgently needed. Here, the gene encoding a new α-helical peptide, Hp1090, was screened from the venomous gland cDNA library of the scorpion Heterometrus petersii. Structural analysis showed that Hp1090 is an amphipathic α-helical peptide. In vitro HCV RNA inhibitory assays indicated that Hp1090 peptide inhibited HCV infection with an IC(50) of 7.62 μg/ml (5.0 μM), whereas Hp1035 peptide, showing high homology to Hp1090, exhibited no anti-HCV activity. Hp1090 acted as a viricide against HCV particles in vitro and prevented the initiation of HCV infection. Furthermore, this peptide interacted with HCV particles directly and rapidly permeabilized phospholipid membranes. Collectively, it seems that Hp1090 is virocidal for HCV in vitro, directly interacting with the viral membrane and decreasing the virus infectivity. These results suggest that Hp1090 could be considered an anti-HCV lead compound with virocidal mechanism that offers a potential therapeutic approach to HCV infection. Our work opens a new avenue for antiviral drug discovery in natural scorpion venom.