GLTP-fold interaction with planar phosphatidylcholine surfaces is synergistically stimulated by phosphatidic acid and phosphatidylethanolamine

Xiuhong Zhai, William E. Momsen, Dmitry A. Malakhov, Ivan A. Boldyrev, Maureen M. Momsen, Julian G. Molotkovsky, Howard L. Brockman, Rhoderick E Brown

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8 Scopus citations

Abstract

Among amphitropic proteins, human glycolipid transfer protein (GLTP) forms a structurally-unique fold that translocates on/off membranes to specifically transfer glycolipids. Phosphatidylcholine (PC) bilayers with curvature- induced packing stress stimulate much faster glycolipid intervesicular transfer than nonstressed PC bilayers raising questions about planar cytosol-facing biomembranes being viable sites for GLTP interaction. Herein, GLTP-mediated desorption kinetics of fl uorescent glycolipid (tetramethyl-boron dipyrromethene (BODIPY)-label) from lipid monolayers are assessed using a novel microfl uidics-based surface balance that monitors lipid lateral packing while simultaneously acquiring surface fl uorescence data. At biomembrane-like packing (30-35 mN/m), GLTP uptake of BODIPY-glycolipid from POPC monolayers was nearly nonexistent but could be induced by reducing surface pressure to mirror packing in cur vature-stressed bilayers. In contrast, 1-palmitoyl- 2-oleoyl- phosphatidylethanolamine (POPE) matrices supported robust BODIPY-glycolipid uptake by GLTP at both high and low surface pressures. Unexpectedly, negativelycharged cytosol-facing lipids, i.e., phosphatidic acid and phosphatidylserine, also supported BODIPY-glycolipid uptake by GLTP at high surface pressure. Remarkably, including both 1-palmitoyl-2-oleoyl- sn -glycero-3-phosphate (5 mol%) and POPE (15 mol%) in POPC synergistically activated GLTP at high surface pressure. Our study shows that matrix lipid headgroup composition, rather than molecular packing per se, is a key regulator of GLTP-fold function while demonstrating the novel capabilities of the microfl uidicsbased film balance for investigating protein-membrane interfacial interactions.

Original languageEnglish (US)
Pages (from-to)1103-1113
Number of pages11
JournalJournal of Lipid Research
Volume54
Issue number4
DOIs
StatePublished - Apr 1 2013

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Keywords

  • BODIPY-glycosphingolipid fluorescence
  • Glycolipid transfer protein
  • Lipid composition
  • Lipid monolayer lateral packing
  • Microfl uidic surface balance
  • Protein interaction with planar model membranes

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