Interaction of the E. coli Alkaline Phosphatase Precursor with Model Phospholipid Membranes

N. I. Mikhaleva,^1,2 A. E. Kalinin,¹ Yu. G. Molotkovsky,³ and M. A. Nesmeyanova¹

¹Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, Pushchino, Moscow Region, 142292 Russia; fax: (095) 923-36-02; E-mail: mikhaleva@ibpm.serpukhov.su

²To whom correspondence should be addressed.

³Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, ul. Miklukho-Maklaya 16/10, Moscow, 117871 Russia.

Submitted August 19, 1996; revision submitted October 7, 1996.

An interaction of a precursor of the E. coli secreted alkaline phosphatase (prePhoA) containing a signal peptide and model bilayer membranes prepared from the lipids of E. coli has been studied. The interaction was evaluated by monitoring of the state of the lipid phase by fluorescence spectroscopy. The role of the signal peptide in this process was evaluated by a comparative study of the interaction of the mature alkaline phosphatase which does not contain the signal peptide with the model membranes. The precursor was shown to be inserted into the lipid bilayer since the anisotropy of a fluorescent hydrophobic probe, diphenylhexatriene, was enhanced. The intensity of the process is determined by the presence of the signal peptide and depends on the pH of the medium. The data indicate that the mature polypeptide chain of the enzyme also has affinity for the membrane.

KEY WORDS: Escherichia coli, prePhoA, signal peptide, anionic phospholipids, fluorescence anisotropy.

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