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Updated: Jul 11, 2026
Antimicrobial Peptides Produced by Selective Pressure Incorporation of Non-canonical Amino Acids
Published on: May 4, 2018
AFM studies of inhibition effect in binding of antimicrobial peptide and immune proteins
Jong Soo Kim1, Soonnam Jang, Uisuk Kim
1School of Environmental Science and Engineering, Pohang University of Science and Technology, Pohang 790-784, Korea.
Abstract:
By using atomic force microscopy (AFM), we clearly show that the antimicrobial peptide affects the molecular interaction between lipopolysaccharide (LPS) and immune proteins (lipopolysaccharide binding protein [LBP] and CD14). To reconstruct an in vivo interaction, LBP and LPS (the Ra, Rc, and Re forms from Salmonella minnesota, with varying lengths of the saccharide region) were immobilized onto the AFM tip using a chemical spacer linker. We examined the interaction between the proteins on the tip and model lipid bilayer biomembranes including CD14, in both the presence and absence of the antimicrobial peptide, polymyxin B (PMB). When LPS was present, the binding force between the LBP-LPS complex and CD14 increased dramatically, compared to that seen between LBP and CD14 alone. Longer LPS saccharide regions resulted in higher binding forces. The data suggest that LPS may have an important influence on the binding of LBP to CD14 and that the saccharide region of LPS is influential in this regard. It was also found that the antimicrobial peptide PMB, at or above a particular concentration, specifically inhibited the binding between LBP-LPS and CD14.
Insights
The antimicrobial peptide polymyxin B inhibits lipopolysaccharide binding protein and CD14 interaction. This study reveals how lipopolysaccharide structure influences binding forces, impacting immune responses.
Area of Science:
- Immunology
- Biophysics
- Microbiology
Background:
- Lipopolysaccharide (LPS) is a key component of Gram-negative bacteria.
- Lipopolysaccharide binding protein (LBP) and CD14 are crucial immune proteins involved in LPS recognition.
- Understanding molecular interactions is vital for developing new antimicrobial strategies.
Purpose of the Study:
- To investigate the effect of antimicrobial peptide polymyxin B (PMB) on the interaction between LPS and immune proteins LBP and CD14.
- To elucidate the role of LPS structure, specifically the saccharide region, in modulating these interactions.
- To quantify binding forces using atomic force microscopy (AFM).
Main Methods:
- Atomic force microscopy (AFM) was employed to measure molecular binding forces.
- Lipopolysaccharide (LPS) and LBP were immobilized on an AFM tip.
- Model lipid bilayer biomembranes containing CD14 were used to study interactions.
- Experiments were conducted in the presence and absence of polymyxin B (PMB).
Main Results:
- LPS significantly increased the binding force between LBP and CD14 compared to LBP alone.
- Longer saccharide regions of LPS resulted in higher binding forces.
- Polymyxin B (PMB) inhibited the LBP-LPS-CD14 interaction at specific concentrations.
Conclusions:
- LPS plays a critical role in modulating the binding affinity between LBP and CD14.
- The saccharide region of LPS is a key determinant of binding strength.
- Polymyxin B effectively disrupts this critical immune recognition complex.
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