2QI9: Abc-transporter Btucd In Complex With Its Periplasmic Binding Protein Btuf

Citation:
Abstract
BtuCD is an adenosine triphosphate-binding cassette (ABC) transporter that translocates vitamin B12 from the periplasmic binding protein BtuF into the cytoplasm of Escherichia coli. The 2.6 angstrom crystal structure of a complex BtuCD-F reveals substantial conformational changes as compared with the previously reported structures of BtuCD and BtuF. The lobes of BtuF are spread apart, and B12 is displaced from the binding pocket. The transmembrane BtuC subunits reveal two distinct conformations, and the translocation pathway is closed to both sides of the membrane. Electron paramagnetic resonance spectra of spin-labeled cysteine mutants reconstituted in proteoliposomes are consistent with the conformation of BtuCD-F that was observed in the crystal structure. A comparison with BtuCD and the homologous HI1470/71 protein suggests that the structure of BtuCD-F may reflect a posttranslocation intermediate.
PDB ID: 2QI9Download
MMDB ID: 54915
PDB Deposition Date: 2007/7/3
Updated in MMDB: 2007/11
Experimental Method:
x-ray diffraction
Resolution: 2.6  Å
Source Organism:
Similar Structures:
Biological Unit for 2QI9: pentameric; determined by author and by software (PISA)
Molecular Components in 2QI9
Label Count Molecule
Proteins (5 molecules)
2
Vitamin B12 Import System Permease Protein Btuc(Gene symbol: btuC)
Molecule annotation
2
Vitamin B12 Import Atp-binding Protein Btud(Gene symbol: btuD)
Molecule annotation
1
Vitamin B12-binding Protein Btuf(Gene symbol: btuF)
Molecule annotation
Chemicals (14 molecules)
1
2
2
6
3
2
4
4
* Click molecule labels to explore molecular sequence information.

Citing MMDB
.