Interaction of Mutant Alkaline Phosphatase Precursors with Membrane Phospholipids in vivo and in vitro

A. E. Kalinin, N. I. Mikhaleva, A. L. Karamyshev, Z. N. Karamysheva, and M. A. Nesmeyanova^*

Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Moscow Region, 142292 Russia; fax: (095) 923-3602; E-mail: aniram@ibpm.serpukhov.su

^* To whom correspondence should be addressed.

Received December 28, 1998; Revision received March 22, 1999

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Positively charged amino acid residues in the N-terminal domain of the signal peptides of secreted proteins are thought to interact with negatively charged anionic phospholipids during the initiation of secretion. To test this hypothesis, substitutions of the uncharged Ala or the negatively charged Glu residue for the positively charged Lys-20 of the N-terminus of the signal peptide of Escherichia coli alkaline phosphatase were introduced using a modified method of oligonucleotide-directed mutagenesis. We found that Lys-20 is involved in the interaction of the signal peptide with anionic phospholipids in vivo and effects the efficiency of insertion of the signal peptide of isolated precursor into model phospholipid membranes in vitro. We also show that the efficiency of signal peptide insertion into the lipid bilayer depends on the fluidity of the bilayer.

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KEY WORDS: E. coli, alkaline phosphatase, amino acid substitutions, protein translocation, phospholipids

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