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Published on: August 11, 2018
Improving Conformational Stability and Bacterial Membrane Interactions of Antimicrobial Peptides with Amphipathic
Ahmad Habibie1, Rizki Amalia Putri1, Respati Tri Swasono1
1Gadjah Mada University.
Abstract:
Antimicrobial resistance (AMR) has become a massive concern because it causes the loss of human life and an economic burden in many parts of the world. Antimicrobial peptides (AMPs) can be investigated as an alternative solution to combat AMR because their mechanism has the potential to reduce microbe resistance. In this study, the native P01 peptide from Chondrus crispus macroalgae was modified to P01.1, P01.2, and P01.3 peptides via residue mutations and capping of the N- and C-termini to systematically improve their a-helical content, bacterial membrane interaction, and antibacterial activity. C-terminus amidation and mutations to remove helix breaker residues in P01 to give P01.1 peptide enhanced its a-helical stability. Acetylation of the N-terminus P01.1 to give P01.2 peptide further enhanced the a-helical content of the peptide. Mutations of low-to-high helical former residues in P01.2 to give P01.3 peptide further improve its a-helical stability. The binding activity of peptides to a model of Gram-positive membrane is in the following order P01.3 > P01.2 > P01.1 > P01; this is correlated with their antibacterial activity against Gram-positive S. aureus with MICs in the following order P01.3 = 15.63 mg/mL > P01.2 = 125 mg/mL > P01.1 and P01 larger than 250 mg/mL. In a model of Gram-negative membrane, the peptide-membrane binding is in the following order P01.3 = P01.2 > P01.1 > P01; however, P01.3, P01.2, and P01.1 have the same antibacterial activity against Gram-negative E.coli (MIC = 3.91 mg/mL) while P01 has no activity. In conclusion, the a-helical stability and amphipathicity of the peptide have correlation with the membrane binding and antibacterial activity of the peptide.
Insights
Modified antimicrobial peptides (AMPs) from macroalgae show enhanced stability and activity against resistant bacteria. These P01 variants demonstrate improved membrane binding, offering a potential alternative to combat antimicrobial resistance (AMR).
Area of Science:
- Biochemistry
- Microbiology
- Marine Biotechnology
Background:
- Antimicrobial resistance (AMR) poses a significant global health and economic threat.
- Antimicrobial peptides (AMPs) are a promising alternative due to their distinct mechanisms of action.
- Macroalgae-derived peptides offer a novel source for AMP development.
Purpose of the Study:
- To engineer and evaluate modified antimicrobial peptides (AMPs) derived from the P01 peptide of *Chondrus crispus*.
- To systematically enhance a-helical content, bacterial membrane interaction, and antibacterial activity.
- To investigate the structure-activity relationship of modified AMPs against resistant bacteria.
Main Methods:
- Chemical modifications including N- and C-termini capping (amidation, acetylation) and residue mutations were performed on the native P01 peptide.
- Peptide stability was assessed by evaluating a-helical content.
- Peptide-membrane binding affinity was measured using model membranes (Gram-positive and Gram-negative).
- Antibacterial activity was determined by Minimum Inhibitory Concentration (MIC) assays against *Staphylococcus aureus* and *Escherichia coli*.
Main Results:
- Modified peptides P01.1, P01.2, and P01.3 exhibited progressively increased a-helical stability compared to P01.
- Peptide binding to Gram-positive membranes followed the order P01.3 > P01.2 > P01.1 > P01.
- Antibacterial activity against *S. aureus* correlated with membrane binding, with P01.3 showing the highest potency (MIC = 15.63 mg/mL).
- Against *E. coli*, P01.3, P01.2, and P01.1 demonstrated potent activity (MIC = 3.91 mg/mL), while P01 was inactive.
- A strong correlation was observed between enhanced a-helical stability, amphipathicity, membrane binding, and antibacterial efficacy.
Conclusions:
- Structural modifications significantly improve the antibacterial properties of macroalgae-derived AMPs.
- Enhanced a-helical content and amphipathicity are key drivers for improved membrane interaction and antimicrobial activity.
- These engineered AMPs represent a viable strategy to address the challenge of antimicrobial resistance.
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