Antimicrobial Peptide Attacks Pseudomonas aeruginosa

A new study describes how a powerful microbe fighter could be converted into a guided missile that strikes specifically at common bacteria responsible for serious infections throughout the body.

Researchers at the Israel Institute of Technology (Technion, Haifa) have found a way to activate an antimicrobial peptide--a small molecule made of short chains of amino acids--that attacks Pseudomonas aeruginosa. Unlike most antibiotics, antimicrobial peptides can sidestep microbe resistance mechanisms and destroy the organism by brute force, often by simply ripping a hole in a targeted cell; the number and order of amino acids in an antimicrobial peptide determines how it recognizes and attacks an invading microbe. However, this non-specific action can also destroy normal red blood cells.

To build a more useful and less toxic antimicrobial peptide, the researchers removed a few amino acids from one end of a dermaseptin peptide--a well-known family of peptides that destroy a wide range of microbes--and replaced it with a fatty acid molecule, making the peptide deadly against P aeruginosa while leaving other bacteria alone. The new peptide is also 60 times less likely to adhere to red blood cells. The research was reported in the January 2007 issue of the journal Chemistry and Biology.

"Antimicrobial peptides present an obvious advantage over conventional antibiotics,” said Professor Amram Mor of the biotechnology and food engineering faculty. "Many experts believe that one of the factors that might hamper the commercial use of antimicrobial peptides is their prohibitive cost. Therefore, smaller means cheaper and in this case, more potent.”

Pseudomonas aeruginosa is the bacterium behind serious lung infections in people with cystic fibrosis (CF) and some types of pneumonia and meningitis, as well as less serious but widespread infections such as swimmer's ear and urinary tract infections.




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