Trialysin, a novel pore-forming protein from saliva of hematophagous insects activated by limited proteolysis

Trialysin, a novel pore-forming protein from saliva of hematophagous insects activated by limited proteolysis

Author Amino, Rogerio Autor UNIFESP Google Scholar
Martins, Rafael Miyazawa Autor UNIFESP Google Scholar
Procopio, J. Google Scholar
Hirata, Izaura Yoshico Autor UNIFESP Google Scholar
Juliano, Maria Aparecida Autor UNIFESP Google Scholar
Schenkman, Sergio Autor UNIFESP Google Scholar
Institution Universidade Federal de São Paulo (UNIFESP)
Universidade de São Paulo (USP)
Abstract We have characterized a pore-forming lytic protein from the saliva of the hematophagous insect Triatoma infestans, a vector of Chagas disease. This protein, named trialysin, has 22 kDa and is present in the saliva at about 200 mug/ml. Purified trialysin forms voltage-dependent channels in planar lipid bilayers with conductance of 880 +/- 40 pS. It lyses protozoan parasites and bacteria indicating that it has a role in the control of microorganism growth in the salivary glands. At higher concentrations, but below those found in saliva, trialysin can also permeabilize and lyse mammalian cells, suggesting that it might also facilitate insect blood feeding by interfering with the cell response of the host. the translated cDNA sequence of trialysin shows a basic, lysine-rich protein in which the N-terminal region is predicted to form an amphipathic alpha-helical structure with positive charges on one side and hydrophobic amino acids on the opposite side. A synthetic peptide corresponding to this cationic amphipathic alpha-helix induces protozoan lysis and mammalian cell permeabilization, showing that this region is involved in lytic activity. However, the lytic peptide G6V32 is 10-fold less efficient than trialysin in lysing parasites and 100-fold less efficient in permeabilizing mammalian cells. Trialysin activity is about 10-fold reduced in salivary gland homogenates prepared in the presence of an irreversible serine-protease inhibitor. Since trialysin precursor contains an anionic pro-sequence of 33 amino acids contiguous to the cationic amphipathic putative a-helix, we propose that removal of the acidic pro-sequence by limited proteolysis activates trialysin by exposing this lytic basic amphipathic motif.
Language English
Date 2002-02-22
Published in Journal of Biological Chemistry. Bethesda: Amer Soc Biochemistry Molecular Biology Inc, v. 277, n. 8, p. 6207-6213, 2002.
ISSN 0021-9258 (Sherpa/Romeo, impact factor)
Publisher Amer Soc Biochemistry Molecular Biology Inc
Extent 6207-6213
Access rights Open access Open Access
Type Article
Web of Science ID WOS:000173989200069

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