Dependence of PrePhoA-Phospholipid Interaction in vivo and in vitro on Charge of Signal Peptide N-Terminus and Content of Anionic Phospholipids in Membranes

S. N. Zolov, N. I. Mikhaleva, A. E. Kalinin, and M. A. Nesmeyanova^*

Laboratory of Protein Secretion in Bacteria, Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, pr. Nauki 5, Pushchino, Moscow Region, 142290 Russia; fax: (095) 956-3370; E-mail: aniram@ibpm.serpukhov.su

^* To whom correspondence should be addressed.

Received March 27, 2002; Revision received April 3, 2002

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Replacement of the positively charged signal peptide with neutral or negatively charged peptides due to substitution of Lys(-20) in the N-terminal region of the signal peptide leads to decreases in the rate of prePhoA membrane translocation in vivo and in the efficiency of prePhoA insertion into liposomes in vitro. The effect of anionic phospholipids on prePhoA insertion into model membranes is determined by the signal peptide N-terminus charge, while the dependence of prePhoA translocation across the cytoplasmic membrane in vivo is not, under the studied variations in the content of anionic phospholipids. This is evidence of the possibility of direct electrostatic interaction between the signal peptide N-terminus and anionic phospholipids, which in vivo, however, seems to involve some proteins of the Sec machinery.

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KEY WORDS: Escherichia coli, alkaline phosphatase, signal peptide, amino acid substitutions, protein translocation, anionic phospholipids, liposomes

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