Functional characterization of amphipathic α-helix in the osmoregulatory ABC transporter OpuA.
Biochemistry
; 51(25): 5142-52, 2012 Jun 26.
Article
em En
| MEDLINE
| ID: mdl-22656643
ABSTRACT
The ATP-binding-cassette transporter OpuA from Lactococcus lactis is composed of two ATPase subunits (OpuAA) and two subunits (OpuABC) with the transmembrane domain fused to an extracellular substrate-binding protein. Of the almost 1900 homologues of OpuA known to date, a subset has an amino-terminal amphipathic helix (plus extra transmembrane segment) fused to the core of the transmembrane domain of the OpuABC subunit. FRET measurements indicate that the amphipathic α-helix is located close to the membrane surface, where its hydrophobic face interacts with the transport protein rather than the membrane lipids. Next, we determined the functional role of this accessory region by engineering the amphipathic α-helix. We analyzed the consequence of the mutations in intact cells by monitoring growth and transport of glycine betaine under normal and osmotic stress conditions. More detailed studies were performed in hybrid membrane vesicles, proteoliposomes, and bilayer nanodisks. We show that the amphipathic α-helix of OpuA is necessary for high activity of OpuA but is not critical for the biogenesis of the protein or the ionic regulation of transport.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Osmose
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Proteínas de Bactérias
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Lactococcus lactis
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Adenosina Trifosfatases
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Transportadores de Cassetes de Ligação de ATP
Idioma:
En
Revista:
Biochemistry
Ano de publicação:
2012
Tipo de documento:
Article
País de afiliação:
Holanda