Host Defense Peptide Piscidin and Yeast-Derived Glycolipid Exhibit Synergistic Antimicrobial Action through Concerted Interactions with Membranes

Fei Liu; Alexander I Greenwood; Yawei Xiong; Rebecca T Miceli; Riqiang Fu; Kyle W Anderson; Scott A McCallum; Mihaela Mihailescu; Richard Gross; Myriam L Cotten

doi:10.1021/jacsau.3c00506

Host Defense Peptide Piscidin and Yeast-Derived Glycolipid Exhibit Synergistic Antimicrobial Action through Concerted Interactions with Membranes

JACS Au. 2023 Oct 19;3(12):3345-3365. doi: 10.1021/jacsau.3c00506. eCollection 2023 Dec 25.

Authors

Fei Liu¹, Alexander I Greenwood², Yawei Xiong², Rebecca T Miceli^{1

3}, Riqiang Fu⁴, Kyle W Anderson⁵, Scott A McCallum³, Mihaela Mihailescu⁶, Richard Gross^{1

3}, Myriam L Cotten²

Affiliations

¹ Department of Chemistry, Rensselaer Polytechnic Institute, Troy, New York 12180, United States.
² Department of Applied Science, William & Mary, Williamsburg, Virginia 23185, United States.
³ Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180, United States.
⁴ Center of Interdisciplinary Magnetic Resonance, National High Magnetic Field Laboratory, Tallahassee, Florida 32310, United States.
⁵ National Institute of Standards and Technology, Rockville, Maryland 20850, United States.
⁶ Institute for Bioscience and Biotechnology Research, University of Maryland, Rockville, Maryland 20850, United States.

Abstract

Developing new antimicrobials as alternatives to conventional antibiotics has become an urgent race to eradicate drug-resistant bacteria and to save human lives. Conventionally, antimicrobial molecules are studied independently even though they can be cosecreted in vivo. In this research, we investigate two classes of naturally derived antimicrobials: sophorolipid (SL) esters as modified yeast-derived glycolipid biosurfactants that feature high biocompatibility and low production cost; piscidins, which are host defense peptides (HDPs) from fish. While HDPs such as piscidins target the membrane of pathogens, and thus result in low incidence of resistance, SLs are not well understood on a mechanistic level. Here, we demonstrate that combining SL-hexyl ester (SL-HE) with subinhibitory concentration of piscidins 1 (P1) and 3 (P3) stimulates strong antimicrobial synergy, potentiating a promising therapeutic window. Permeabilization assays and biophysical studies employing circular dichroism, NMR, mass spectrometry, and X-ray diffraction are performed to investigate the mechanism underlying this powerful synergy. We reveal four key mechanistic features underlying the synergistic action: (1) P1/3 binds to SL-HE aggregates, becoming α-helical; (2) piscidin-glycolipid assemblies synergistically accumulate on membranes; (3) SL-HE used alone or bound to P1/3 associates with phospholipid bilayers where it induces defects; (4) piscidin-glycolipid complexes disrupt the bilayer structure more dramatically and differently than either compound alone, with phase separation occurring when both agents are present. Overall, dramatic enhancement in antimicrobial activity is associated with the use of two membrane-active agents, with the glycolipid playing the roles of prefolding the peptide, coordinating the delivery of both agents to bacterial surfaces, recruiting the peptide to the pathogenic membranes, and supporting membrane disruption by the peptide. Given that SLs are ubiquitously and safely used in consumer products, the SL/peptide formulation engineered and mechanistically characterized in this study could represent fertile ground to develop novel synergistic agents against drug-resistant bacteria.