Solution structure of the N-terminal amphitropic domain of Escherichia coli glucose-specific enzyme IIA in membrane-mimetic micelles

Guangshun Wang, Paul A. Keifer, Alan Peterkofsky

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43 Scopus citations

Abstract

The N-terminal domain of enzyme IIAGlc of the Escherichia coli phosphoenolpyruvate: sugar phosphotransferase system confers amphitropism to the protein, allowing IIAGlc to shuttle between the cytoplasm and the membrane. To further understand this amphitropic protein, we have elucidated, by NMR spectroscopy, the solution structure of a synthetic peptide corresponding to the N-terminal domain of IIAGlc. In water, this peptide is predominantly disordered, consistent with previous data obtained in the absence of membranes. In detergent micelles of dihexanoylphosphatidylglycerol (DHPG) or sodium dodecylsulfate (SDS), however, residues Phe 3-Val 10 of the peptide adopt a helical conformation in the ensemble of structures calculated on the basis of NOE-derived distance restraints. The root mean square deviations for superimposing the backbone atoms of the helical region are 0.18 Å in DHPG and 0.22 Å in SDS. The structure, chemical shifts, and spin-spin coupling constants all indicate that, of the four lysines in the N-terminal domain of IIAGlc, only Lys 5 and Lys 7 in the amphipathic helical region interact with DHPG. In addition, the peptide-detergent interactions were investigated using intermolecular NOESY experiments. The aliphatic chains of anionic detergents DHPG, SDS, and 2,2-dimethyl-2-silapentane-5-sulfonate sodium salt (DSS) all showed intermolecular NOE cross-peaks to the peptide, providing direct evidence for the putative membrane anchor of IIAGlc in binding to the membrane-mimicking micelles.

Original languageEnglish (US)
Pages (from-to)1087-1096
Number of pages10
JournalProtein Science
Volume12
Issue number5
DOIs
Publication statusPublished - May 1 2003

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Keywords

  • Amphitropism
  • Dihexanoylphosphatidylglycerol
  • IIA
  • Lipid binding
  • Membrane proteins
  • NMR
  • Signal transduction

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology

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