Cytotoxic activity of potato aspartic proteinases could be involved thiorredoxin reductase interaction

MUÑOZ F, MENDIETA JR, PAGANO MR, DALEO GR, GUEVARA MG

Pinamar, Buenos Aires, Argentina

Congreso; X Congreso of Panamerican Association for Biochemistry and Molecular Biology (PABMB), XLI Reunión anual de la Sociedad Argentina de Investigación Bioquímica y Biología Molecular (SAIB), XX Reunión anual de la Sociedad Argentina de Neuroquímica (SAN); 2005

Cytotoxic activity of potato aspartic proteinases could be involved thiorredoxin reductase interaction. 2005 Muñoz F, Mendieta JR, Pagano MR, Daleo GR, Guevara MG. BIOCELL PL-P63. ISSN 0327-9545. Potato aspartic proteinases (StAPs) have in their sequence a domain named "Plant Specific Insert" (PSI) which has a high homology with saposin like proteins (SAPLIPs). This family of proteins are able to permeabilize cell membranes via interaction with lipids and/or thioredoxin reductase (Trx). Previous reports have shown that the cytotoxic activity of one of these proteins, NK-lysin, would be regulated via Trx interaction. We have previously reported the direct relationship between cytotoxic activity of StAPs on Fusarium solani and the capacity of these proteases to produce cell membrane permeabilization mediated by binding to the cell surface. In this work we show that the cytotoxic activity and the capacity of binding to cell surface of spores and hyphae of  F. solani were highly dependent on the integrity of the disulfide bonds, because these activities were inhibited when StAPs were treated with dithiotreitol prior to incubation with fungal structures. The amounts of DTT assayed were selected taking into account the reported DTT concenirations able to inhibit the cytotoxic activity of NK-lysin (0.1-0.5 mM). Results obtained showed that DTT affects the StAPs cytotoxic activity and surface binding capacity in a dose-dependent form. These results encouraged us to search for interaction of antimicrobial plant proteins and peptides with disulfide bridges essential to iheir folding, with plant and/or fungal Trx by analogy with mammalian cell systems.