TAILIEUCHUNG - Báo cáo khoa học: A short proregion of trialysin, a pore-forming protein of Triatoma infestans salivary glands, controls activity by folding the N-terminal lytic motif

Triatoma infestans(Hemiptera: Reduviidae) is a hematophagous insect that transmits the protozoan parasite Trypanosoma cruzi, the etiological agent of Chagas’ disease. Its saliva contains trialysin, a protein that forms pores in membranes. Peptides based on the N-terminus of trialysin lyse cells and fold into a-helical amphipathic segments resembling antimicrobial peptides. Using a specific antiserum against trialysin, we show here that trialysin is synthesized as a precursor that is less active than the protein released after saliva secretion. . | ễFEBS Journal A short proregion of trialysin a pore-forming protein of Triatoma infestans salivary glands controls activity by folding the N-terminal lytic motif Rafael M. Martins1 Rogerio Amino2 Katia R. Daghastanli3 lolanda M. Cuccovia3 Maria A. Juliano4 and Sergio Schenkman1 1 Departamento de Microbiologia Imunologia e Parasitologia Universidade Federalde Sao Paulo Brazil 2 Departamento de Bioquimica Universidade Federalde Sao Paulo Brazil 3 Departamento de Bioquimica Instituto de Quimica Universidade de Sao Paulo Brazil 4 Departamento de Biofisica Universidade Federalde Sao Paulo Brazil Keywords membrane lysis salivary gland trialysin Triatoma infestans Trypanosoma cruzi Correspondence S. Schenkman Departamento de Microbiologia Imunologia e Parasitologia Rua Botucatu 862 8o andar 04023-062 Sao Paulo SP Brazil Fax 55 11 5571 58 77 Tel 55 11 5575 19 96 E-mail sschenkman@ Received 30 August 2007 revised 3 December 2007 accepted 2 January 2008 doi Triatoma infestans Hemiptera Reduviidae is a hematophagous insect that transmits the protozoan parasite Trypanosoma cruzi the etiological agent of Chagas disease. Its saliva contains trialysin a protein that forms pores in membranes. Peptides based on the N-terminus of trialysin lyse cells and fold into a-helical amphipathic segments resembling antimicrobial peptides. Using a specific antiserum against trialysin we show here that trialysin is synthesized as a precursor that is less active than the protein released after saliva secretion. A synthetic peptide flanked by a fluorophore and a quencher including the acidic proregion and the lytic N-terminus of the protein is also less active against cells and liposomes increasing activity upon proteolysis. Activation changes the peptide conformation as observed by fluorescence increase and CD spectroscopy. This mechanism of activation could provide a way to impair the toxic effects of trialysin inside the salivary glands thus .

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