Crystallization and preliminary X-ray crystallographic analysis of the Escherichia coli outer membrane cobalamin transporter BtuB in complex with the carboxy-terminal domain of TonB
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville, Virginia 22908 (United States)
- Interdisciplinary Graduate Program in Biophysics, University of Virginia, Charlottesville, Virginia 22908 (United States)
Crystals of a complex of the E. coli proteins BtuB (outer membrane cobalamin transporter) and TonB (carboxy-terminal domain) diffracting to 2.1 Å resolution have been obtained. The energy-dependent uptake of organometallic compounds and other micronutrients across the outer membranes of Gram-negative bacteria is carried out by outer membrane active-transport proteins that utilize the proton-motive force of the inner membrane via coupling to the TonB protein. The Escherichia coli outer membrane cobalamin transporter BtuB and a carboxy-terminal domain of the TonB protein, residues 147–239 of the wild-type protein, were expressed and purified individually. A complex of BtuB and TonB{sup 147–239} was formed in the presence of the substrate cyanocobalamin (CN-Cbl; vitamin B{sub 12}) and calcium and was crystallized. BtuB was purified in the detergent LDAO (n-dodecyl-N,N-dimethylamine-N-oxide) and the complex was formed in a detergent mixture of LDAO and C{sub 8}E{sub 4} (tetraethylene glycol monooctylether). Crystals were obtained by sitting-drop vapor diffusion, with the reservoir containing 30%(v/v) polyethylene glycol (PEG 300) and 100 mM sodium acetate pH 5.2. The crystals belong to space group P2{sub 1}2{sub 1}2{sub 1} (unit-cell parameters a = 74.3, b = 82.4, c = 122.6 Å). The asymmetric unit consists of a single BtuB–TonB complex. Data sets have been collected to 2.1 Å resolution at a synchrotron beamline (APS SER-CAT 22-ID)
- OSTI ID:
- 22360210
- Journal Information:
- Acta Crystallographica. Section F, Vol. 62, Issue Pt 7; Other Information: PMCID: PMC2242962; PMID: 16820681; PUBLISHER-ID: pu5141; OAI: oai:pubmedcentral.nih.gov:2242962; Copyright (c) International Union of Crystallography 2006; Country of input: International Atomic Energy Agency (IAEA); ISSN 1744-3091
- Country of Publication:
- United Kingdom
- Language:
- English
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