The Droserasin 1 PSI: A Membrane-Interacting Antimicrobial Peptide from the Carnivorous Plant Drosera capensis

Abstract

The Droserasins, aspartic proteases from the carnivorous plant Drosera capensis, contain a 100-residue plant-specific insert (PSI) that is post-translationally cleaved and independently acts as an antimicrobial peptide. PSIs are of interest not only for their inhibition of microbial growth, but also because they modify the size of lipid vesicles and strongly interact with biological membranes. PSIs may therefore be useful for modulating lipid systems in NMR studies of membrane proteins. Here we present the expression and biophysical characterization of the Droserasin 1 PSI (D1 PSI.) This peptide is monomeric in solution and maintains its primarily α -helical secondary structure over a wide range of temperatures and pH values, even under conditions where its three disulfide bonds are reduced. Vesicle fusion assays indicate that the D1 PSI strongly interacts with bacterial and fungal lipids at pH 5 and lower, consistent with the physiological pH of D. capensis mucilage. It binds lipids with a variety of head groups, highlighting its versatility as a potential stabilizer for lipid nanodiscs. Solid-state NMR spectra collected at a field strength of 36 T, using a unique series-connected hybrid magnet, indicate that the peptide is folded and strongly bound to the membrane. Molecular dynamics simulations indicate that the peptide is stable as either a monomer or a dimer in a lipid bilayer. Both the monomer and the dimer allow the passage of water through the membrane, albeit at different rates.

An acidophilic fungus is integral to prey digestion in a carnivorous plant

“…3e ), demonstrating the fungus’s direct involvement in sundew digestion. The addition of protease inhibitor significantly lengthened the reopening time in both treatments, corroborating previous findings that the peptidases were primarily involved during the digestion process 40–42 . Application of biotinylated bovine serum albumin on the collected mucilage showed a declining trend during digestion and was significantly reduced after 24 hours from the A. crateriforme inoculated-samples (inoculated sample: 36.9 % vs without: 44.0%, P=0.03, Wilcoxon rank sum exact test, Fig.…”

Gland cell responses to feeding in Drosera capensis, a carnivorous plant

“…Drosera is one of the largest and most diverse genera of carnivorous plants (CPs). The structure and physiology of these plants have been of great interest ever since Darwin (1875) described their carnivorous nature, not only because of the exceptional way they acquire nutrition, but also because of their economic importance in pharmacy due to their antimicrobial metabolites and their sticky, trapping glue (Grevenstuk et al 2009;Sprague-Piercy et al 2020). Plants are characterized by leaves bearing protuberances on the margin and upper surface of their blades; they consist of a slender In memory of Ursula Lütz-Meindl Handling Editor: Andreas Holzinger stalk, or tentacle, that bears a multicellular glandular head.…”

Antibacterial Peptides derived from Capra hircus Goat Milk Casein

“…Furthermore, these peptides inhibit bacteria growth through intracellular mechanisms targeting receptors. [9,10] In recent years, AMPs have developed through chemical synthesis and hydrolysis of protein from organisms. [11,12] Specifically, milk is among the most popular sources of new AMPs by hydrolysis protein method.…”

“…In antibacterial activity, cationic AMPs disturb membrane cell bacteria in the lysis of bacteria cells. Furthermore, these peptides inhibit bacteria growth through intracellular mechanisms targeting receptors [9,10] …”