Lytic Activity and Structural Differences of Amphipathic Peptides Derived from Trialysin
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- 作者：Rafael M. Martins ; Maurí ; cio L. Sforç ; a ; Rogé ; rio Amino ; Maria Aparecida Juliano ; Sé ; rgio Oyama ; Jr. ; Luiz Juliano ; Thelma A. Pertinhez ; Alberto Spisni ; and Sergio Schenkman
- 刊名：Biochemistry
- 出版年：2006
- 出版时间：February 14, 2006
- 年：2006
- 卷：45
- 期：6
- 页码：1765 - 1774
- 全文大小：535K
- 年卷期：v.45,no.6(February 14, 2006)
- ISSN：1520-4995
文摘
Trialysin is a pore-forming protein found in the saliva of Triatoma infestans (Hemiptera,Reduviidae), the insect vector of Chagas' disease. The protein is active against a broad range of cell typesfrom bacteria to eukaryotic cells. Recognizing that the N-terminus of trialysin harbors the lytic motif[Amino, R., Martins, R. M., Procopio, J., Hirata, I. Y., Juliano, M. A., and Schenkman, S. (2002) J. Biol.Chem. 277, 6207-6213], we designed a set of peptides scanning this region to investigate the structuralbasis of its biological function. Peptides encompassing residues 1-32 (P6), 1-27 (P7), and 6-32 (P5)efficiently induced lysis of the protozoan parasite Trypanosoma cruzi and Escherichia coli in the 0.4-9.0
M range, while much higher concentrations were required to cause hemolysis. Other more internal peptides,including peptide P2 (residues 21-47) and others up to residue 52, were less effective. P6 turned out tobe the most active of all. P7 has a significantly higher activity than P5 against E. coli, while P5 has ahemolytic activity comparable to that of P6. CD spectroscopy showed that all tested peptides acquire acomparable helical content in solvent mixtures or in detergent micelles. The solution structure of P2 andP5-P7 was determined in a 30% trifluoroethanol/water mixture by nuclear magnetic resonance. All peptidesexhibit a structure characterized by a central helical fold, and except for P2, which does not show acontinuous hydrophobic surface, they are amphipathic. The structural models show that P5 and P7 extendtheir structural similarities with the most active peptide, P6, in either the C-terminus or the N-terminus.Amino acid substitutions in the N-terminus of P6 improved hemolysis but did not change the activityagainst T. cruzi. These results suggest that while amphipathicity is essential for the lytic activity, theselectivity of the active peptides for specific organisms appears to be associated with the structural featuresof their N- and C-termini.
M range, while much higher concentrations were required to cause hemolysis. Other more internal peptides,including peptide P2 (residues 21-47) and others up to residue 52, were less effective. P6 turned out tobe the most active of all. P7 has a significantly higher activity than P5 against E. coli, while P5 has ahemolytic activity comparable to that of P6. CD spectroscopy showed that all tested peptides acquire acomparable helical content in solvent mixtures or in detergent micelles. The solution structure of P2 andP5-P7 was determined in a 30% trifluoroethanol/water mixture by nuclear magnetic resonance. All peptidesexhibit a structure characterized by a central helical fold, and except for P2, which does not show acontinuous hydrophobic surface, they are amphipathic. The structural models show that P5 and P7 extendtheir structural similarities with the most active peptide, P6, in either the C-terminus or the N-terminus.Amino acid substitutions in the N-terminus of P6 improved hemolysis but did not change the activityagainst T. cruzi. These results suggest that while amphipathicity is essential for the lytic activity, theselectivity of the active peptides for specific organisms appears to be associated with the structural featuresof their N- and C-termini.