Cytosolic and nuclear localization of the cytolytic and insecticidal plantprotein enterolobin

Enterolobin is a 52 905 Da cytolytic, inflammatory and insecticidal protein obtained from seeds of the Brazilian tree Enterolobium contortisiliquum. I t shares structural and functional similarities with aerolysins, pore-formi ng toxins from Aeromonas bacteria. These characteristics suggest that enter olobin might play a defence role in the plant. In order to determine the lo calization and distribution of this phytocytolysin in the seed cells, immun ocytochemical labelling experiments were carried out using rabbit anti-ente rolobin serum and colloidal gold conjugated with goat antirabbit IgG, Light microscopy results indicated that labelling was widely distributed in the cytosol (33%) of cotyledon cells and in the nucleus (67%), Electron microsc opy results confirmed the presence of enterolobin in both the cytosol and n ucleus, Putative nuclear localization signals (NLS) were found in the seque nce of enterolobin.