Activation of phospholipase A2 by temporin B: formation of antimicrobial peptide-enzyme amyloid-type cofibrils.
Phospholipases A2 have been shown to be activated in a concentration dependent manner by a number of antimicrobial peptides, including melittin, magainin 2, indolicidin, and temporins B and L. Here we used fluorescently labelled bee venom PLA2 (PLA2D) and the saturated phospholipid substrate 1,2-dipalmitoyl-glycero-sn-3-phosphocholine (L-DPPC), exhibiting a lag-burst behaviour upon the initiation of the hydrolytic reaction by PLA2. Increasing concentrations of Cys-temporin B and its fluorescent Texas red derivative (TRC-temB) caused progressive shortening of the lag period. TRC-temB/PLA2D interaction was observed by Förster resonance energy transfer (FRET), with maximum efficiency coinciding with the burst in hydrolysis. Subsequently, supramolecular structures became visible by microscopy, revealing amyloid-like fibrils composed of both the activating peptide and PLA2. Reaction products, palmitic acid and 1-palmitoyl-2-lyso-glycero-sn-3-phosphocholine (lysoPC, both at >8 mol%) were required for FRET when using the non-hydrolysable substrate enantiomer 2,3-dipalmitoyl-glycero-sn-1-phosphocholine (D-DPPC). A novel mechanism of PLA2 activation by co-fibril formation and associated conformational changes is suggested.
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Christian
C
Helsinki Biophysics and Biomembrane Group, Medical Biochemistry, Institute of Biomedicine, P.O. Box 63 (Haartmaninkatu 8), FIN-00014, University of Helsinki, Finland.
Domanov
Yegor A
YA
Killian
J Antoinette
JA
Kinnunen
Paavo K J
PK
D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry; D000682:Amyloid / Q000737:chemistry; D000818:Animals; D023181:Antimicrobial Cationic Peptides; D001514:Bee Venoms / Q000201:enzymology; D055592:Biophysical Phenomena; D002942:Circular Dichroism; D004789:Enzyme Activation / Q000187:drug effects; D031541:Fluorescence Resonance Energy Transfer; D005456:Fluorescent Dyes; D066298:In Vitro Techniques; D008081:Liposomes / Q000737:chemistry; D008856:Microscopy, Fluorescence; D046912:Multiprotein Complexes; D054467:Phospholipases A2 / Q000737:chemistry / Q000378:metabolism*; D011506:Proteins / Q000737:chemistry / Q000494:pharmacology*
D000682:Amyloid; D023181:Antimicrobial Cationic Peptides; D001514:Bee Venoms; D005456:Fluorescent Dyes; D008081:Liposomes; D046912:Multiprotein Complexes; D011506:Proteins; C104501:temporin; D015060:1,2-Dipalmitoylphosphatidylcholine; D054467:Phospholipases A2