Membrane activity of the pentaene macrolide didehydroroflamycoin in model lipid bilayers
Alena Koukalová1, Šárka Pokorná2, Radovan Fišer3
1J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejškova 2155/3, 182 23 Prague 8, Czech Republic; Faculty of Science, Charles University in Prague, Albertov 6, 128 43 Prague 2, Czech Republic.
Abstract:
Didehydroroflamycoin (DDHR), a recently isolated member of the polyene macrolide family, was shown to have antibacterial and antifungal activity. However, its mechanism of action has not been investigated. Antibiotics from this family are amphiphilic; thus, they have membrane activity, their biological action is localized in the membrane, and the membrane composition and physical properties facilitate the recognition of a particular compound by the target organism. In this work, we use model lipid membranes comprised of giant unilamellar vesicles (GUVs) for a systematic study of the action of DDHR. In parallel, experiments are conducted using filipin III and amphotericin B, other members of the family, and the behavior observed for DDHR is described in the context of that of these two heavily studied compounds. The study shows that DDHR disrupts membranes via two different mechanisms and that the involvement of these mechanisms depends on the presence of cholesterol. The leakage assays performed in GUVs and the conductance measurements using black lipid membranes (BLM) reveal that the pores that develop in the absence of cholesterol are transient and their size is dependent on the DDHR concentration. In contrast, cholesterol promotes the formation of more defined structures that are temporally stable.
Insights
Didehydroroflamycoin disrupts cell membranes through two distinct mechanisms. Its action varies with cholesterol presence, forming transient pores without it and stable structures with it.
Area of Science:
- Membrane biophysics
- Antimicrobial drug mechanisms
- Polyene macrolide antibiotics
Background:
- Didehydroroflamycoin (DDHR) is a novel polyene macrolide with known antibacterial and antifungal properties.
- The mechanism of action for DDHR remains largely uncharacterized.
- Polyene macrolides are amphiphilic and exert their biological effects through interactions with cell membranes.
Purpose of the Study:
- To investigate the membrane disruption mechanism of Didehydroroflamycoin (DDHR).
- To compare DDHR's membrane activity with that of filipin III and amphotericin B.
- To elucidate the role of cholesterol in DDHR-induced membrane alterations.
Main Methods:
- Utilizing model lipid membranes, specifically giant unilamellar vesicles (GUVs) and black lipid membranes (BLMs).
- Conducting leakage assays in GUVs to assess membrane permeability.
- Performing conductance measurements in BLMs to study pore formation.
Main Results:
- DDHR disrupts membranes via two distinct mechanisms, influenced by cholesterol.
- In the absence of cholesterol, DDHR forms transient pores with size dependent on concentration.
- Cholesterol facilitates the formation of stable, well-defined DDHR-cholesterol structures.
Conclusions:
- DDHR exhibits versatile membrane interaction capabilities.
- Cholesterol significantly modulates DDHR's mechanism of membrane disruption.
- Understanding these mechanisms can inform the development of new antimicrobial strategies.
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