Amphipol-trapped ExbB-ExbD membrane protein complex from Escherichia coli: a biochemical and structural case study.
J Membr Biol
; 247(9-10): 1005-18, 2014 Oct.
Article
em En
| MEDLINE
| ID: mdl-24862870
ABSTRACT
Nutrient import across Gram-negative bacteria's outer membrane is powered by the proton-motive force, delivered by the cytoplasmic membrane protein complex ExbB-ExbD-TonB. Having purified the ExbB4-ExbD2 complex in the detergent dodecyl maltoside, we substituted amphipol A8-35 for detergent, forming a water-soluble membrane protein/amphipol complex. Properties of the ExbB4-ExbD2 complex in detergent or in amphipols were compared by gel electrophoresis, size exclusion chromatography, asymmetric flow field-flow fractionation, thermal stability assays, and electron microscopy. Bound detergent and fluorescently labeled amphipol were assayed quantitatively by 1D NMR and analytical ultracentrifugation, respectively. The structural arrangement of ExbB4-ExbD2 was examined by EM, small-angle X-ray scattering, and small-angle neutron scattering using a deuterated amphipol. The amphipol-trapped ExbB4-ExbD2 complex is slightly larger than its detergent-solubilized counterpart. We also investigated a different oligomeric form of the two proteins, ExbB6-ExbD4, and propose a structural arrangement of its transmembrane α-helical domains.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Polímeros
/
Propilaminas
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Tensoativos
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Proteínas de Escherichia coli
Idioma:
En
Revista:
J Membr Biol
Ano de publicação:
2014
Tipo de documento:
Article
País de afiliação:
Canadá