Exploring the Dual Interaction of Natural Rhamnolipids with Plant and Fungal Biomimetic Plasma Membranes through Biophysical Studies.

Noadya Monnier,Manuel Dauchez,Magali Deleu,Aurélien Furlan,Sébastien Buchoux,Catherine Sarazin,Sonia Rippa

doi:10.3390/ijms20051009

Abstract

Rhamnolipids (RLs) are potential biocontrol agents for crop culture protection. Their mode of action has been proposed as dual, combining plant protection activation and antifungal activities. The present work focuses on the interaction of natural RLs with plant and fungi membrane models at the molecular scale. Representative models were constructed and the interaction with RLs was studied by Fourier transform infrared (FTIR) and deuterium nuclear magnetic resonance (2H NMR) spectroscopic measurements. Molecular dynamic (MD) simulations were performed to investigate RL insertion in lipid bilayers. Our results showed that the RLs fit into the membrane models and were located near the lipid phosphate group of the phospholipid bilayers, nearby phospholipid glycerol backbones. The results obtained with plant plasma membrane models suggest that the insertion of RLs inside the lipid bilayer did not significantly affect lipid dynamics. Oppositely, a clear fluidity increase of fungi membrane models was observed. This effect was related to the presence and the specific structure of ergosterol. The nature of the phytosterols could also influence the RL effect on plant plasma membrane destabilization. Subtle changes in lipid dynamics could then be linked with plant defense induction and the more drastic effects associated with fungal membrane destabilization.

Highlights

Rhamnolipids (RLs) are secondary metabolites naturally produced by bacteria of the genera Pseudomonas and Burkholderia with biosurfactant properties
J.oMdoilf. iSccai.t2i0o1n9,i2n0,dxuced by exogenous molecules on the hydrophobic part of PC through a4bosfo2r0bance measurements of alkyl chains (3000–2800 cm−1), and on the hydrophilic part through absorbance mteharsouurgemh aebnstosrobfaCnc=eOmbeoansudrse(m18e0n0ts–1o4f 0C0=Ocmb−o1n)dasn(d18p00h–o1s4p0h0actme g−1r)oaunpdsp(h13o0sp0–h1a1te50grcomu−ps1)(1[93]0.0–1150 cm−H1)e[9re]., maximum absorbance corresponding to PLPC terminal CH3 groups, at 2954 cm−1, and asHymerme, emtraicxiamnudmsyambsmorebtarinccve icborrarteiospnosnodfinCgHt2ogPrLoPuCpstaertm29in2a3l aCnHd32g8r5o2ucpms,−a1t, 2w95e4recumn−a1,ffaencdted by RLassy(mFimguerteric2aa)n. dCsoynmvemresetrliyc, vCi=brOataionndsPo=f OCHm2agxriomuupsmatab29so23rbaanndce28w52ercems−h1,ifwteedretounhaigffheecrtewdabvyeRnuLsmbers by(Fbiogtuhrem2oan).oC- oonrvdeir-sReLlys
At the center of the bilayers, local dynamic were more fluid with faster C–2H bond fluctuation decreasing spectra M1. For order parameters (SCD) values. These results suggest that RLs do not strongly disturb the dynamic of this phospholipid membrane model

Summary

Introduction

Rhamnolipids (RLs) are secondary metabolites naturally produced by bacteria of the genera Pseudomonas and Burkholderia with biosurfactant properties. Rhamnolipids are produced as a mix of compounds with one or two rhamnose residues (mono- or di-RLs) forming a polar head and linked through a beta-glycosylic bond to one or two 3-hydroxy fatty acids. Pseudomonas aeruginosa RLs, which are the most studied RLs, are produced as a mixture of mainly α-L-rhamnopyranosyl-βhydroxydecanoyl-β-hydroxy-decanoate and 2-O-α-L-rhamnopyranosyl-α-L-rhamnopyranosyl-βhydroxydecanoyl-β-hydroxydecanoate [1], (Figure 1). Those compounds were first studied for their.

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