Abstract
Antimicrobial peptides (AMPs) are considered as a promising agent to overcome the drug-resistance of bacteria. Large numbers of AMPs have been identified from the skin secretion of Rana pipiens, including brevinins, ranatuerins, temporins and esculentins. In this study, the cDNA precursor of a broad-spectrum antimicrobial peptide, ranatuerin-2Pb, was cloned and identified. Additionally, two truncated analogues, RPa and RPb, were synthesised to investigate the structure-activity relationship of ranatuerin-2Pb. RPa lost antimicrobial activity against Candida albicans, MRSA, Enterococcus faecalis and Pseudomonas aeruginosa, while RPb retained its broad-spectrum antimicrobial activity. Additionally, ranatuerin-2Pb, RPa and RPb demonstrated inhibition and eradication effects against Staphylococcus aureus biofilm. RPb showed a rapid bacterial killing manner via membrane permeabilization without damaging the cell membrane of erythrocytes. Moreover, RPb decreased the mortality of S. aureus infected Galleria mellonella larvae. Collectively, our results suggested that RPb may pave a novel way for natural antimicrobial drug design.
Highlights
In recent decades, the overuse of conventional antibiotics has aggravated the resistance of bacteria, and this has become a serious problem facing the world [1]
The removal of last two residues of ranatuerin-2Pb contributed to the decrease of the helical content for RPa that could explain the reduction of antimicrobial, anticancer and haemolytic activity for RPa compared to the parent peptide (Table 2)
Our results revealed that a delicate balance of amphipathicity and α-helical is necessary for broad-spectrum antimicrobial activity and less toxicity
Summary
The overuse of conventional antibiotics has aggravated the resistance of bacteria, and this has become a serious problem facing the world [1]. Facing this severe problem, the World Health. Ranatuerin-2 peptides, were initially identified in the skin of Lithobates catesbeianus and have been found in most species of North American, Chinese and Japanese frogs [7,8]. These peptides contain a C-terminal cyclic domain; the primary structure of these peptides was poorly conserved with several residue deletions with only the cysteine residues invariant. Two peptides, Biomolecules 2019, 9, 249; doi:10.3390/biom9060249 www.mdpi.com/journal/biomolecules
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