PHOSPHATIDYLETHANOLAMINE MEDIATES INSERTION OF THE CATALYTIC DOMAIN OF LEADER PEPTIDASE IN MEMBRANES

Leader peptidase is an integral membrane protein of E, coli and it cat alyses the removal of most signal peptides from translocated precursor proteins. In this study it is shown that when the transmembrane ancho rs are removed in vivo, the remaining catalytic domain can bind to inn er and outer membranes of E, coli, Furthermore, the purified catalytic domain binds to inner membrane vesicles and vesicles composed of puri fied inner membrane lipids with comparable efficiency. It is shown tha t the interaction is caused by penetration of a part of the catalytic domain between the lipids. Penetration is mediated by phosphatidyletha nolamine, the most abundant lipid in E, coli, and does not seem to dep end on electrostatic interactions. A hydrophobic segment around the ca talytically important residue serine 90 is required for the interactio n with membranes. (C) 1998 Federation of European Biochemical Societie s.