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Updated: Oct 5, 2025
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Antimicrobial Peptides Produced by Selective Pressure Incorporation of Non-canonical Amino Acids
Published on: May 4, 2018
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Rare by Natural Selection: Disulfide-Bonded Supramolecular Antimicrobial Peptides
Yizhaq Engelberg1, Peleg Ragonis-Bachar1, Meytal Landau1,2
1Department of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel.
Biomacromolecules
|January 21, 2022
Summary
Human LL-3717-29 antimicrobial peptides form fibrils. Disulfide bonds in LL-3717-29 mutants control fibril assembly and antibacterial activity, explaining natural selection against certain cysteine-containing peptides.
Area of Science:
- Biochemistry
- Structural Biology
- Microbiology
Background:
- Human LL-3717-29 is a key antimicrobial peptide known for forming thermostable supramolecular fibrils.
- These fibrils are implicated in surrounding and potentially inhibiting bacterial cells.
Purpose of the Study:
- To elucidate the structural basis of LL-3717-29 fibril formation and its relation to antibacterial activity.
- To investigate the role of specific cysteine substitutions and disulfide bonds in modulating fibril assembly and antimicrobial function.
Main Methods:
- Crystal structure determination of LL-3717-29 with an I24C substitution.
- Analysis of disulfide-bonded dimers and their assembly into helical fibrillar structures.
- Assessment of position-dependent antibacterial activity of various cysteine mutants.
Main Results:
- The crystal structure revealed disulfide-bonded dimers of LL-3717-29 I24C, which further assemble into densely packed helical fibrils.
- Antibacterial activity was controllable and position-dependent in cysteine mutants, linked to disulfide bond regulation and supramolecular assembly.
- Fibril morphology and antibacterial mechanisms may vary based on interactions with specific bacterial species.
Conclusions:
- Intermolecular disulfide bonds critically influence the assembly of LL-3717-29 into functional supramolecular structures.
- The sensitivity of these disulfide bonds to redox conditions may explain the natural selection against short helical antimicrobial peptides with odd cysteine numbers.
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