The Flocculating Cationic Polypetide from Moringa oleifera Seeds Damages Bacterial Cell Membranes by Causing Membrane Fusion

Abstract

A cationic protein isolated from the seeds of the Moringa oleifera tree has been extensively studied for use in water treatment in developing countries and has been proposed for use in antimicrobial and therapeutic applications. However, the molecular basis for the antimicrobial action of this peptide, Moringa oleifera cationic protein (MOCP), has not been previously elucidated. We demonstrate here that a dominant mechanism of MOCP antimicrobial activity is membrane fusion. We used a combination of cryogenic electron microscopy (cryo-EM) and fluorescence assays to observe and study the kinetics of fusion of membranes in liposomes representing model microbial cells. We also conducted cryo-EM experiments on E. coli cells where MOCP was seen to fuse the inner and outer membranes. Coarse-grained molecular dynamics simulations of membrane vesicles with MOCP molecules were used to elucidate steps in peptide adsorption, stalk formation, and fusion between membranes.

Biological, nutritional, and therapeutic significance of Moringa oleifera Lam

“…Antimicrobial properties are possibly attributed by 4‐(α‐ l ‐rhamnopyranosyloxy)benzyl isothiocyanate, methyl N‐4‐(α‐ l ‐rhamnopyranosyloxy)benzyl carbamate and 4‐(β‐ d ‐glucopyranosyl‐1 → 4‐α‐ l ‐rhamnopyranosyloxy)‐benzyl thiocarboxamide (Oluduro, Aderiye, Connolly, Akintayo, & Famurewa, ; Padla et al, ); water soluble lectine protein (Coelho et al, ; Ferreira et al, ; Moura et al, ); flocculating cationic polypeptides (Shebek et al, ); niazimicin (Rim et al, 2014); glycosides 4‐(α‐ l ‐rhamnosyloxy)‐benzyl isothiocyanate, 4‐(α‐ l ‐rhamnosyloxy)‐phenylacetonitrile and moringine (Jahn, Musnad, & Burgstaller, ); proanthocyanidins (Maldini et al, ) in seeds; niaziminin, niazinin (Wang, Chen, & Wu, ), and silver nanoparticles (Prasad & Elumalai, ) in leave extract; cardiac glycosides in pods (Arora & Onsare, ); kaempferol, rhamnetin, kaempferitin, isoquercitrin, and pterygospermin in flowers; spirochin and anthonine in roots (Farooq, Rai, Tiwari, Khan, & Farooq, ; Mehta, Shukla, Bukhariya, & Charde, ; Raj, Gopalakrishnan, Yadav, & Dorairaj, ); and aglycon of deoxy‐niazimicine (N‐benzyl, S‐ethyl thioformate) in bark (Nikkon et al, ). It is cleared from previous studies that seeds may also act directly upon microorganisms and showed broader antimicrobial spectrum than other parts of MO.…”

“…The coagulation efficacy of MOCP is observed to be increased with an increase in the initial turbidity of water (Katayon et al, ). Owing to amphiphilic properties, MOCP integrate into the bacterial membranes and are specifically kill several microorganisms, including waterborne pathogens (Shebek et al, ). The seed contain polypeptides, a coagulant, used to treat river water with suspended solid particles and groundwater (Lijesh & Malhotra, ).…”

A Chitin-binding Protein Purified from Moringa oleifera Seeds Presents Anticandidal Activity by Increasing Cell Membrane Permeability and Reactive Oxygen Species Production

“…However, as the primary structures of all Mo -CBPs proteins are very similar, it was not possible to predict the Mo -CBP 2 sequence. For instance, it was reported that the flocculent peptides MOCP 2.1 and MOCP 2.2 are distinguished by a single amino acid residue (Shebek et al, 2015). Similar situation might occur with Mo -CBP 2 and other M. oleifera proteins.…”

Mini Review on Antimicrobial Activity and Bioactive Compounds of Moringa oleifera

“…The flocculation cationic polypeptide showed antibacterial activity by damaging bacterial cell membranes and causing fusion between membranes. Also, it has been used widely in water purification processes [24]. Structure-function studies of Flo peptides revealed that a sequence prone to form a helix-loophelix structural motif is important to the bactericidal activity and the hydrophobic proline residues within the protruding loop are essential for maintaining bactericidal activity [25].…”