SPECIFICITY OF CITOTOXIC ACTIVITY OF RECOMBINANT DOMAIN StAP-PSIr

MUÑOZ, FERNANDO F.; MENDIETA, JULIETA R.; PAGANO MARIANA R.; PAGGI, ROBERTO A.; DALEO, GUSTAVO R.; GUEVARA, MARÍA G.

Rosario, Santa fe, Argentina

Congreso; Reunión Anual de la Sociedad Argentina de Investigacion en Bioquímica y Biología Molecular; 2006

We have previously reported that Potato Aspartic Proteases (StAP1 and StAP3) have antimicrobial activity towards plant pathogen microorganisms and human pathogens bacteria. Besides, we have cloned and expressed the Plant Specific Insert (PSI), a domain present in the StAPs sequence. This recombinant peptide (StAP-PSIr) has antifungal activity against F. solani. In this study, we tested the capacity of StAP-PSIr to affect the viability of cysts of Phytophthora infestans, an economically important potato pathogen, as well as three bacterial strain which cause human disease (Eschcerichia coli, Bacillus cereus, Staphylococcus aureus). The results showed that StAP-PSIr has antimicrobial activity against P. infestans (IC50: 0.22  mM) involving plasma membrane permeabilization. StAP-PSIr present cytotoxic activity on bacteria culture in a dose-dependent manner. The IC50 obtained for B. cereus, E. coli and S. aureus were 0.24 mM, 0.3  mM and 2.67 mM respectively. On the other hand, we analysed the specificity of StAP-PSIr, using a culture of plant cells and human erythrocytes. When tobacco cells and human erythrocytes were incubated with StAP-PSIr, the cell viability was not affected. Therefore, we conclude that StAP-PSIr have specific antimicrobial activity against the plant and human pathogens microrganisms.