Recently, the research group led by Dr. WANG Junfeng from High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences, investigated the interaction between antimicrobial peptides (AMPs) and lipopolysaccharide (LPS), an important component of the outer membrane of Gram-negative bacteria. A manuscript entitled " Lipopolysaccharide Induces Amyloid formation of Antimicrobial Peptide HAL-2" was accepted by Biochimica et Biophysica Acta (BBA) – Biomembranes and published online on August 7, 2014 (doi: 10.1016/j.bbamem.2014.07.028).
AMPs possess an unusually broad spectrum of activity, and are promising candidates for the development of therapeutic drugs against resistant pathogen. The net cationicity and amphipathicity of AMPs mediate the interaction between AMPs and anionic components of the membrane and cause cell death. The highly anionic lipopolysaccharide (LPS) which constitutes the lipid portion of the outer membrane of Gram-negative bacteria, contributes to the integrity of the outer membrane, and protects the cell against the action of chemicals.
This research focused on the interactions between LPS and an antimicrobial peptide HAL-2 which was isolated from the venom of the eusocial bee Halictus sexcinctus. The results showed that after electrostatically binding to LPS, HAL-2 adopts a -strand conformation and consequently forms amyloid aggregates, which play an important role in HAL-2 antimicrobial activity. Many amyloid peptides have been discovered to be involved in human diseases including Abeta of Alzheimer's disease and type II diabetes. This is the first report that LPS induces the AMPs amyloid formation and contributes to their antimicrobial activity. Overall, this study provided novel insights into the molecular basis of the antimicrobial activity mediated by LPS, and it could provide information to design novel antimicrobial peptides for future therapeutic purposes.
The above research was supported by Natural Science Foundation of China and Hefei Center for Physical Science and Technology.
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