The efficacy of the antibacterial peptide,pyrrhocoricin, is finely regulated by its amino acid residues and active domains |
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Authors: | Bencivengo Anne-Marie Cudic Mare Hoffmann Ralf Otvos Laszlo |
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Institution: | 1.The Wistar Institute, c[Philadelphia, PA, U.S.A ;2.Biologisch-Medizinisches Forschungszentrum, Heinrich-Heine-Universit?t, Düsseldorf, Germany ; |
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Abstract: | Summary Pyrrhocoricin, a highly active antibacterial peptide isolated from insects, inhibits chaperone-assisted protein folding via
binding to the 70 kDa heat shock protein DnaK with its amino terminal half. The C-terminus functions as an intracellular delivery
module. In the current study, chimeras consisting of the putative functional units of pyrrhocoricin and a related peptide,
drosocin, were made, and it was found that some mixed and matched sequences retained their ability to killEscherichia coli, Salmonella typhimurium andAgrobacterium tumefaciens. While pyrrhocoricin appeared to have a more universal pharmacophore, drosocin featured a more robust intracellular delivery
unit. We also identified the minimal length of pyrrhocoricin that is needed to efficiently kill bacteria. While for activity
againstS. typhimurium the peptide could not be shortened, againstE. coli it was sufficient to have a Vall-Ile16 amino-terminal fragment. Although Vall was not part of the Asp2-Pro 10 pharmacophore
(it could be replaced with other residues), it could not be eliminated and apparently played an important role in defining
the activity of the peptide. Indeed, when Val1 was replaced with lysine, not only the efficacy of pyrrhocoricin to kill the
sensitive strains increased significantly, resulting in the most active antimicrobial peptide against some clinical strains
ever made, but the modified peptide was also able to killPseudomonas aeruginosa, an originally unresponsive bacterium in the low μg ml−1 concentration range. However, this substitution likely influenced the interaction with bacterial membranes rather than that
with the target protein, and therefore the dominant mode of action of the Lysl-pyrrhocoricin peptide may feature membrane
disintegration instead of DnaK inhibition. |
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Keywords: | delivery module membrane pharmacophore substitution |
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