Trans-bilayer asymmetry of anoplin binding governs phase transitions in mixed model membranes

Krajnović, Vedrana; Fehér, Bence; Jakas, Andreja; Stránský, Jan; Bakarić, Danijela (2026) Trans-bilayer asymmetry of anoplin binding governs phase transitions in mixed model membranes. Journal of Liposome Research . ISSN 1532-2394 (In Press)

PDF - Accepted Version - article
Restricted to Closed Access until 1 November 2027.
Available under License Creative Commons Attribution Non-commercial No Derivatives.
Download (931kB) | Request a personal copy from author

Official URL: https://www.tandfonline.com/journals/ilpr20

Abstract

Antimicrobial peptides are promising alternatives to conventional antibiotics due to their membrane-disrupting capabilities. Here, we investigated the action of anoplin (ANP), a cationic-amphipathic decapeptide, on model bacterial membranes composed of zwitterionic 1,2-dipalmitoyl-sn-glycero-3-phosphatidylcholine (DPPC) or 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) and anionic 1,2-dipalmitoyl-sn-glycero-3-phospho-(1′-rac-glycerol) (DPPG) (3/1 molar ratio). Using differential scanning calorimetry (DSC), turbidity measurements (UV-Vis spectroscopy), and circular dichroism (CD) spectroscopy, we examined how zwitterionic headgroup chemistry and leaflet distribution asymmetry – external adherence (ANPout) versus both internal and external adherence (ANPin/out) – modulate lipid segregation and membrane thermotropic properties before leakage. In DPPC/DPPG bilayers, ANP positioning governed membrane viscoelasticity: ANPout made the bilayer more fluid, whereas ANPin/out increased membrane rigidity. In contrast, in DPPE/DPPG bilayers, the promoted DPPG segregation was largely independent of ANP distribution. Importantly, cooperativity signatures changed in both mixtures: in the DPPC-containing mixture, they differ for the ANPout system, whereas in all DPPE-containing mixtures they do not display a common sigmoidal profile. CD spectroscopy revealed that ANP maintains a helical conformation in DPPC/DPPG across both gel and fluid phases, whereas DPPE/DPPG fosters β-sheet-rich peptide aggregation. Coupled with the intrinsic negative curvature of DPPE, this enhanced aggregation likely induces membrane corrugations at the surface that obscure the obtained turbidity profiles. Besides demonstrating that zwitterionic lipid modulates ANP’s secondary structure and domain segregation, the ANP distribution along the membrane midplane critically regulates bilayer mechanical properties. This highlights leaflet-specific inter-lipid interactions and peptide translocation as pivotal factors driving ANP-mediated membrane disruption and permeabilization.

Item Type:

Article

Uncontrolled Keywords:

anoplin (ANP; GLLKRIKTLLNH2); mixed lipid membranes; 1,2-dipalmitoyl-sn-glycero-3-phospho-(1’-rac-glycerol) (DPPG) segregation; turbidity (UV-Vis spectroscopy); phase transition temperatures (DSC); conformational change (CD spectroscopy)

Subjects:

NATURAL SCIENCES > Chemistry > Physical Chemistry

Divisions:

Division of Organic Chemistry and Biochemistry

Projects:

Project title	Project leader	Project code	Project type
Model of demyelination on a molecular scale on physiological and pathological conditions	Danijela Bakarić	UIP-2020-02-7669	HrZZ
Antimicrobial peptides based on natural marine antimicrobials: Design and study of their mode of action	Andreja Jakas	IP-2024-05-1216	HrZZ
A new approach in the structural characterization of drug delivery systems	Danijela Bakarić	NPOO.C3.2.R3-I1.05.0050	EU
Metaproteomika patvorenih namirnica	Mario Cindrić	NPOO.C3.2.R3-I1.04.0122	EU