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FEBS Lett. 2004 May 7;565(1-3):65-9.

The insect antimicrobial peptide, L-pyrrhocoricin, binds to and stimulates the ATPase activity of both wild-type and lidless DnaK.

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Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, 1501 Kings Highway, Shreveport, LA 71130-3932, USA.


Recent reports have indicated that insect antimicrobial peptides kill bacteria by inhibiting the molecular chaperone DnaK. It was proposed that the antimicrobial peptide, all-L-pyrrhocoricin (L-PYR), binds to two sites on DnaK, the conventional substrate-binding site and the multi-helical C-terminal lid, and that inhibition of DnaK comes about from the lid mode of binding. In this report, we show using two different assays that L-PYR binds to and stimulates the ATPase activity of both wild-type and a lidless variant of DnaK. Our study shows that L-PYR interacts with DnaK much like the all-L NR (NRLLLTG) peptide, which is known to bind in the conventional substrate-binding site of DnaK. L-PYR antimicrobial activity is thus a consequence of the competitive inhibition of bacterial DnaK.

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