Lipid composition regulates the orientation of transmembrane helices in HorA, an ABC multidrug transporter
| Autor: | Hassane S. Mchaourab, Cédric Govaerts, Adelin Gustot, Jean Marie Ruysschaert, Smriti |
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| Rok vydání: | 2010 |
| Předmět: |
Stereochemistry
Biochimie Lipid Bilayers Molecular Sequence Data Sciences de la matière vivante ATP-binding cassette transporter Biophysique Biochemistry ATP-Binding Cassette Transporters -- genetics Protein Structure Secondary Phosphatidylethanolamines -- pharmacology chemistry.chemical_compound Membrane Biology Spectroscopy Fourier Transform Infrared Adenosine Triphosphatases -- metabolism Lipid Bilayers -- chemistry ATP-Binding Cassette Transporters -- chemistry Amino Acid Sequence Lipid bilayer Spin label Molecular Biology Protein secondary structure Phosphatidylethanolamine Adenosine Triphosphatases Liposome ATP-Binding Cassette Transporters -- metabolism Sequence Homology Amino Acid Bilayer Circular Dichroism Phosphatidylethanolamines Electron Spin Resonance Spectroscopy Biologie moléculaire Biological Transport Cell Biology Sciences bio-médicales et agricoles Lactobacillus -- metabolism Sciences biomédicales Transmembrane domain Lactobacillus Phosphatidylcholines -- pharmacology chemistry Liposomes Phosphatidylcholines Biologie cellulaire ATP-Binding Cassette Transporters Biologie |
| Zdroj: | The Journal of biological chemistry, 285 (19 |
| ISSN: | 1083-351X |
| Popis: | ATP-binding cassette (ABC) transporters constitute a large class of molecular pumps whose central role in chemotherapy resistance has highlighted their clinical relevance. We investigated whether the lipid composition of the membrane affects the function and structure of HorA, a bacterial ABC multidrug transporter. When the transporter was reconstituted in a bilayer where phosphatidylethanolamine (PE), the main lipid of the bacterial membrane, was replaced with phosphatidylcholine (PC), ATP hydrolysis and substrate transport became uncoupled. Although ATPase activity was maintained, HorA lost its ability to extrude the prototypical substrate Hoechst33342. Attenuated Total Reflection-Fourier Transform Infrared spectroscopy (ATR-FTIR) revealed that, although the secondary structure of the protein was unaffected, the orientation of the transmembrane helices (TM) was modified by the change in lipid composition. The orientation of the backbone carbonyls indicated that the helices opened wider in PE versus PC-containing liposomes, with 10 degrees difference. This was supported by hydrogen/deuterium exchange studies showing increased protection of the backbone from the solvent in PC-containing liposomes. Electron Paramagnetic Resonance was used to further probe the structural change. In the PC-containing liposomes we observed increased mobility of the spin label in TM4, along with increased exposure to molecular oxygen, used as a hydrophobic quencher. This indicates that the lipid change induced modification of the orientation of TM4, exposing Cys-180 to the lipid phase. The lipid composition of the bilayer thus modulates the structure of HorA, and in turn its ability to extrude its substrates. Journal Article SCOPUS: ar.j info:eu-repo/semantics/published |
| Databáze: | OpenAIRE |
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