Assessing Interactions between a Polytopic Membrane Protein and Lipid Bilayers Using Differential Scanning Calorimetry and Solid-State NMR

James R. Banigan, Maureen Leninger, Ampon Sae Her, Nathaniel Traaseth

Research output: Contribution to journalArticle

Abstract

It is known that the lipid composition within a cellular membrane can influence membrane protein structure and function. In this Article, we investigated how structural changes to a membrane protein upon substrate binding can impact the lipid bilayer. To carry out this study, we reconstituted the secondary active drug transporter EmrE into a variety of phospholipid bilayers varying in headgroup and chain length and carried out differential scanning calorimetry (DSC) and solid-state NMR experiments. The DSC results revealed a difference in cooperativity of the lipid phase transition for drug-free EmrE protonated at glutamic acid 14 (i.e., proton-loaded form) and the tetraphenylphosphonium (TPP+) bound form of the protein (i.e., drug-loaded form). To complement these findings, we acquired magic-angle-spinning (MAS) spectra in the presence and absence of TPP+ by directly probing the phospholipid headgroup using 31P NMR. These spectra showed a reduction in lipid line widths around the main phase transition for samples where EmrE was bound to TPP+ compared to the drug free form. Finally, we collected oriented solid-state NMR spectra on isotopically enriched EmrE that displayed chemical shift perturbations to both transmembrane and loop residues upon TPP+ binding. All of these results prompt us to propose a mechanism whereby substrate-induced changes to the structural dynamics of EmrE alters the surrounding lipids within the bilayer.

Original languageEnglish (US)
Pages (from-to)2314-2322
Number of pages9
JournalJournal of Physical Chemistry B
Volume122
Issue number8
DOIs
StatePublished - Mar 1 2018

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Lipid bilayers
Membrane Lipids
Lipids
lipids
Differential scanning calorimetry
Membrane Proteins
heat measurement
Nuclear magnetic resonance
membranes
solid state
proteins
Proteins
Membranes
drugs
nuclear magnetic resonance
scanning
Phospholipids
Pharmaceutical Preparations
Phase transitions
interactions

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

Cite this

Assessing Interactions between a Polytopic Membrane Protein and Lipid Bilayers Using Differential Scanning Calorimetry and Solid-State NMR. / Banigan, James R.; Leninger, Maureen; Her, Ampon Sae; Traaseth, Nathaniel.

In: Journal of Physical Chemistry B, Vol. 122, No. 8, 01.03.2018, p. 2314-2322.

Research output: Contribution to journalArticle

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