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AFM Study of Nanoscale Membrane Perturbation Induced by Antimicrobial Lipopeptide C14 KYR
Sawinee Nasompag1, Pawinee Siritongsuk2, Saengrawee Thammawithan2
1Interdisciplinary Graduate Program in Genetic Engineering, The Graduate School, Kasetsart University, Bangkok 10900, Thailand.
Abstract:
Lipopeptides have been extensively studied as potential antimicrobial agents. In this study, we focused on the C14-KYR lipopeptide, a modified version of the KYR tripeptide with myristic acid at the N-terminus. Here, membrane perturbation of live E. coli treated with the parent KYR and C14-KYR peptides was compared at the nanoscale level using AFM imaging. AFM analyses, including average cellular roughness and force spectroscopy, revealed the severe surface disruption mechanism of C14-KYR. A loss of surface roughness and changes in topographic features included membrane shrinkage, periplasmic membrane separation from the cell wall, and cytosolic leakage. Additional evidence from synchrotron radiation FTIR microspectroscopy (SR-FTIR) revealed a marked structural change in the membrane component after lipopeptide attack. The average roughness of the E. coli cell before and after treatment with C14-KYR was 129.2 ± 51.4 and 223.5 ± 14.1 nm, respectively. The average rupture force of the cell treated with C14-KYR was 0.16 nN, four times higher than that of the untreated cell. Our study demonstrates that the mechanistic effect of the lipopeptide against bacterial cells can be quantified through surface imaging and adhesion force using AFM.
Insights
The lipopeptide C14-KYR severely disrupts E. coli membranes, causing shrinkage and leakage. Atomic Force Microscopy (AFM) quantified these nanoscale effects, revealing significant surface changes and increased cell rupture force.
Area of Science:
- Microbiology
- Biophysics
- Materials Science
Background:
- Lipopeptides are investigated as antimicrobial agents.
- The C14-KYR lipopeptide is a modified KYR tripeptide with myristic acid.
Purpose of the Study:
- To compare the membrane perturbation of live E. coli by KYR and C14-KYR lipopeptides.
- To elucidate the nanoscale surface disruption mechanism of C14-KYR using AFM.
Main Methods:
- Atomic Force Microscopy (AFM) imaging for nanoscale analysis.
- AFM force spectroscopy to measure cell adhesion and rupture forces.
- Synchrotron radiation FTIR microspectroscopy (SR-FTIR) to analyze membrane structural changes.
Main Results:
- C14-KYR caused severe surface disruption, including membrane shrinkage and cytosolic leakage.
- AFM revealed increased cell roughness from 129.2 nm to 223.5 nm after C14-KYR treatment.
- The rupture force of C14-KYR treated cells was four times higher than untreated cells (0.16 nN).
Conclusions:
- C14-KYR exhibits a potent membrane disruption mechanism against E. coli.
- AFM is effective in quantifying lipopeptide-induced bacterial cell damage at the nanoscale.
- This study provides mechanistic insights into lipopeptide antimicrobial action.
