2ONK: Abc Transporter Modbc In Complex With Its Binding Protein Moda

Citation:
Abstract
ATP-binding cassette (ABC) transporter proteins carry diverse substrates across cell membranes. Whereas clinically relevant ABC exporters are implicated in various diseases or cause multidrug resistance of cancer cells, bacterial ABC importers are essential for the uptake of nutrients, including rare elements such as molybdenum. A detailed understanding of their mechanisms requires direct visualization at high resolution and in distinct conformations. Our recent structure of the multidrug ABC exporter Sav1866 has revealed an outward-facing conformation of the transmembrane domains coupled to a closed conformation of the nucleotide-binding domains, reflecting the ATP-bound state. Here we present the 3.1 A crystal structure of a putative molybdate transporter (ModB2C2) from Archaeoglobus fulgidus in complex with its binding protein (ModA). Twelve transmembrane helices of the ModB subunits provide an inward-facing conformation, with a closed gate near the external membrane boundary. The ATP-hydrolysing ModC subunits reveal a nucleotide-free, open conformation, whereas the attached binding protein aligns the substrate-binding cleft with the entrance to the presumed translocation pathway. Structural comparison of ModB2C2A with Sav1866 suggests a common alternating access and release mechanism, with binding of ATP promoting an outward-facing conformation and dissociation of the hydrolysis products promoting an inward-facing conformation.
PDB ID: 2ONKDownload
MMDB ID: 44742
PDB Deposition Date: 2007/1/24
Updated in MMDB: 2012/11
Experimental Method:
x-ray diffraction
Resolution: 3.1  Å
Source Organism:
Similar Structures:
Biological Unit for 2ONK: pentameric; determined by author and by software (PISA)
Molecular Components in 2ONK
Label Count Molecule
Proteins (5 molecules)
2
Molybdate/tungstate ABC Transporter, Atp-binding Protein(Gene symbol: AF_RS00455)
Molecule annotation
2
Molybdate/tungstate ABC Transporter, Permease Protein(Gene symbol: AF_RS00460)
Molecule annotation
1
Molybdate/tungstate Binding Protein(Gene symbol: AF_RS00465)
Molecule annotation
Chemicals (6 molecules)
1
1
2
2
3
3
* Click molecule labels to explore molecular sequence information.

Citing MMDB
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