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Interaction between Antimicrobial Peptide CM15 and a Model Cell Membrane Affected by CM15 Terminal Amidation and the
Liang Ma1, Yongsheng Luo1, Yong-Hao Ma1
1State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing, 210096, Jiangsu Province, P. R. China.
Abstract:
Antimicrobial peptides (AMPs) have been proposed as an effective class of antimicrobial agents against microorganisms. In this work, the interaction between an antimicrobial peptide, CM15, and a negatively charged phospholipid bilayer, DPPG, was studied via sum frequency generation (SFG) vibrational spectroscopy. Two structurally correlated characteristic variables were introduced to reveal the interaction mechanism/efficiency, i.e. C-terminal amidation and temperature variation (∼20 °C, room temperature, and ∼35 °C, close to human body temperature). Experimental results indicated that owing to the increased positive charge, C-terminal amidation resulted in rapid adsorption onto the bilayer surface and efficient disruption of the outer layer, exhibiting less ordered insertion orientation. The elevated temperature (from ∼20 °C to ∼35 °C) promoted the penetration of both the outer and inner leaflets by the peptides and finally led to the disruption of the whole bilayer owing to the enhanced fluidity of the bilayer. From the perspective of the interaction mechanism, this experimental study provides two practical cues to understand the disruption process of the negatively charged model biomembranes, which can lay the structural foundation for designing and developing high-efficiency antimicrobial peptides.
Insights
Antimicrobial peptides (AMPs) disrupt model cell membranes. C-terminal amidation and higher temperatures enhance AMP disruption efficiency by altering peptide charge and membrane fluidity.
Area of Science:
- Biophysics
- Biochemistry
- Materials Science
Background:
- Antimicrobial peptides (AMPs) are a promising class of antimicrobial agents.
- Understanding AMP interaction with cell membranes is crucial for developing new therapeutics.
Purpose of the Study:
- To investigate the interaction mechanism between the antimicrobial peptide CM15 and a negatively charged phospholipid bilayer (DPPG).
- To explore the effects of C-terminal amidation and temperature variations on AMP-membrane interactions and disruption efficiency.
Main Methods:
- Sum frequency generation (SFG) vibrational spectroscopy was employed to study peptide-bilayer interactions.
- Experiments were conducted at different temperatures (∼20 °C and ∼35 °C) and with modified CM15 peptides (C-terminal amidation).
Main Results:
- C-terminal amidation of CM15 increased positive charge, leading to rapid adsorption and efficient disruption of the outer bilayer leaflet.
- Elevated temperatures (∼20 °C to ∼35 °C) enhanced bilayer fluidity, promoting peptide penetration and complete bilayer disruption.
- Peptide orientation and insertion depth were influenced by both amidation and temperature.
Conclusions:
- C-terminal amidation and increased temperature are effective strategies for enhancing antimicrobial peptide efficacy.
- The study provides insights into the structural basis for designing more potent antimicrobial peptides targeting negatively charged biomembranes.
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