Antibacterial peptides in interaction with model membranes studied by various spectroscopic methods
L. Bednárová1, P. Maloň1, H. Dlouhá1, E. Kočišová2, K. Hofbauerová2,3, V.Kopecký Jr.2
1Institute of Organic Chemistry and Biochemistry AS CR, Flemingovo náměstí 2, Prague 6, 166 10, Czech Republic
2Institute of Physics, Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 5, Praha 2, 121 165, Czech Republic
3Institute of Microbiology AS CR, Vídeňská 1083, Prague 4, 142 20, Czech Republic
Naturally occurring antimicrobial peptides (AMPs) represent one successful form of chemical defense of eukaryotic cells against bacteria, protozoa, fungi, and viruses . Many of them have been already isolated, thousands of their synthetic analogs were synthesized and a broad spectrum of their antimicrobial, anticancer and antiviral activities was proven [2, 3]. In spite of large number of known AMPs and their therapeutic potential, exact mechanism of their action remains a matter of controversy. There is a consensus that these peptides selectively disrupt cell membranes and it is believed that their amphiphatic structure plays an important role in this process.
Interaction of peptides with membranes or their models leads to changes of their secondary structure, which could be detected using various spectroscopic methods. Here we present spectroscopic studies of halictines, AMP isolated from the venom of the eusocial bee Halictus sexcinctus, which exhibited potent antimicrobial activity against Gram-positive and Gram-negative bacteria but also noticeable hemolytic activity . Circular dichroism, infrared and Raman spectra of HAL-1 (Gly-Met-Trp-Ser-Lys-Ile-Leu-Gly-His-Leu-Ile-Arg-NH2) in a membrane/like environment, showed ability to form a-helical structure whereas the HAL peptide exhibits random coil conformation in water. The attempts to measure HAL peptides in an interaction with liposomes with different kinds of membranes are presented as well.
1. M. Zasloff, Nature, 415, (2002), 389.
2. R. E. Hancock, G. Diamond, Trends Microbiol., 9, (2000), 402.
3. R. E. Hancock, M. G. Scott, Proc. Natl. Acad. Sci. U.S.A., 97, (2000), 8856.
4. L. Monincová, M. Buděšínský, J. Slaninová, O. Hovorka, J. Cvačka, Z. Voburka, V. Fučík, L. Borovičková, L. Bednárová, J. Straka,V. Čeřovský, Amino Acids, submitted.
The Grant Agency of the Czech Republic is gratefully acknowledged for support (No. 208/10/0376).