# The acidic latex protein from Hevea brasiliensis serves as an anionic antimicrobial peptide

## TL;DR

A protein from rubber trees shows strong antimicrobial properties and could be used as a new type of antimicrobial peptide.

## Contribution

Hev b5 is identified as an anionic antimicrobial peptide with chitinase activity and enhanced antibacterial effects in the presence of metal ions.

## Key findings

- rHev b5 showed significant chitinase activity and antibacterial effects against both Gram-positive and Gram-negative bacteria.
- Antibacterial activity was enhanced with zinc or calcium ions, indicating membrane binding via metal ion-mediated salt bridges.
- Hev b5's properties suggest it could serve as a dual-action antimicrobial and antifungal agent.

## Abstract

Hev b5 is a unique acidic protein identified as an allergen in natural latex and latex gloves, known for stimulating histamine release from human basophils sensitized with serum from latex-allergic individuals. It is rich in glutamic acid and proline residues arranged in repeated motifs. The protein’s unusual amino acid composition includes 48% negatively charged residues and 13% positively charged residues.

The recombinant form of Hev b5 (rHev b5) was produced in Escherichia coli. Its chitinase activity, which may provide antifungal properties by breaking down chitin in phytopathogen cell walls, was assessed. Additionally, the antibacterial activity of rHev b5 against Gram-positive and Gram-negative bacteria, including Bacillus cereus, Staphylococcus aureus, E. coli and Salmonella typhi, was evaluated. The potential enhancement of this activity in the presence of calcium or zinc ions was investigated to understand the underlying mechanism involving binding to microbial membranes via metal ion-mediated cationic salt bridges.

rHev b5 exhibited significant chitinase activity and demonstrated substantial antibacterial effects against both Gram-positive and Gram-negative bacteria. The antibacterial activity was notably enhanced in the presence of zinc or calcium ions, suggesting that rHev b5 binds to microbial membranes through metal ion-mediated cationic salt bridges, leading to cell lysis and microbial death.

Antimicrobial properties and chitinase activity of Hev b5 underline its potential as an anionic antimicrobial peptide, offering both antifungal and antibacterial defenses. These findings position Hev b5 as a promising candidate for further research in antimicrobial peptide applications.