Rational design of cationic antimicrobial peptides by the tandem of leucine-rich repeat
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Antimicrobial peptides represent ancient host defense effector molecules present in organisms across the evolutionary spectrum. Lots of antimicrobial peptides were synthesized based on well-known structural motif widely existed in a variety of lives. Leucine-rich repeats (LRRs) are sequence motifs present in over 60,000 proteins identified from viruses, bacteria, and eukaryotes. To elucidate if LRR motif possesses antimicrobial potency, two peptides containing one or two LRRs were designed. The biological activity and membrane–peptide interactions of the peptides were analyzed. The results showed that the tandem of two LRRs exhibited similar antibacterial activity and significantly weaker hemolytic activity against hRBCs than the well-known membrane active peptide melittin. The peptide with one LRR was defective at antimicrobial and hemolytic activity. The peptide containing two LRRs formed α-helical structure, respectively, in the presence of membrane-mimicking environment. LRR-2 retained strong resistance to cations, heat, and some proteolytic enzymes. The blue shifts of the peptides in two lipid systems correlated positively with their biological activities. Other membrane-peptide experiments further provide the evidence that the peptide with two LRRs kills bacteria via membrane-involving mechanism. The present study increases our new understanding of well-known LRR motif in antimicrobial potency and presents a potential strategy to develop novel antibacterial agents.
KeywordsAntimicrobial peptides Leucine-rich repeat Membrane–peptide interaction
Minimum inhibitory concentration
Minimal hemolytic concentration
This work was supported by grants from the National Basic Research Program (2012CB124703), the National Natural Science Foundation of China (31072046 and 31272453), the Program for Innovative Research Team of Universities in Heilongjiang Province, the China Postdoctoral Science Foundation (2012M510082), and the Heilongjiang Postdoctoral Foundation (LBH-Z11238). We are pleased to thank Guo Hu, Xin Zhu, and Ze Y. Wang for technical assistance.
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