POSITIVELY CHARGED LYSINE AT THE N-TERMINUS OF THE SIGNAL PEPTIDE OF THE ESCHERICHIA-COLI ALKALINE-PHOSPHATASE PROVIDES THE SECRETION EFFICIENCY AND IS INVOLVED IN THE INTERACTION WITH ANIONIC PHOSPHOLIPIDS

Positively charged amino acid residues at the N-terminus of the signal peptide (SP) have been proposed to play a significant role in the ini tial step of protein secretion in bacteria. To test this hypothesis, L ys(-20) of the Escherichia coli alkaline phosphatase SP was replaced b y other amino acid residues, and the effect of these substitutions on protein maturation was studied. The introduction of negatively charged and hydrophobic amino acids resulted in a decrease in secretion effic iency and impaired the SP-APL interaction, whereas His and Tyr had no significant effect. A structural analysis of the SP-APL interaction su ggests that the positively charged Lys(-20) determines the stability o f the complex. (C) 1997 Federation of European Biochemical Societies.