1nqe: Difference between revisions
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[[Image:1nqe.gif|left|200px]] | [[Image:1nqe.gif|left|200px]] | ||
'''OUTER MEMBRANE COBALAMIN TRANSPORTER (BTUB) FROM E. COLI''' | {{Structure | ||
|PDB= 1nqe |SIZE=350|CAPTION= <scene name='initialview01'>1nqe</scene>, resolution 2.00Å | |||
|SITE= | |||
|LIGAND= <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene> and <scene name='pdbligand=C8E:(HYDROXYETHYLOXY)TRI(ETHYLOXY)OCTANE'>C8E</scene> | |||
|ACTIVITY= | |||
|GENE= btuB ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=562 Escherichia coli]) | |||
}} | |||
'''OUTER MEMBRANE COBALAMIN TRANSPORTER (BTUB) FROM E. COLI''' | |||
==Overview== | ==Overview== | ||
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==About this Structure== | ==About this Structure== | ||
1NQE is a [ | 1NQE is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1NQE OCA]. | ||
==Reference== | ==Reference== | ||
Substrate-induced transmembrane signaling in the cobalamin transporter BtuB., Chimento DP, Mohanty AK, Kadner RJ, Wiener MC, Nat Struct Biol. 2003 May;10(5):394-401. PMID:[http:// | Substrate-induced transmembrane signaling in the cobalamin transporter BtuB., Chimento DP, Mohanty AK, Kadner RJ, Wiener MC, Nat Struct Biol. 2003 May;10(5):394-401. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/12652322 12652322] | ||
[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
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[[Category: vitamin b12]] | [[Category: vitamin b12]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Mar 20 13:00:18 2008'' | ||
Revision as of 14:00, 20 March 2008
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| , resolution 2.00Å | |||||||
|---|---|---|---|---|---|---|---|
| Ligands: | and | ||||||
| Gene: | btuB (Escherichia coli) | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
OUTER MEMBRANE COBALAMIN TRANSPORTER (BTUB) FROM E. COLI
OverviewOverview
The outer membranes of Gram-negative bacteria possess transport proteins essential for uptake of scarce nutrients. In TonB-dependent transporters, a conserved sequence of seven residues, the Ton box, faces the periplasm and interacts with the inner membrane TonB protein to energize an active transport cycle. A critical mechanistic step is the structural change in the Ton box of the transporter upon substrate binding; this essential transmembrane signaling event increases the affinity of the transporter for TonB and enables active transport to proceed. We have solved crystal structures of BtuB, the outer membrane cobalamin transporter from Escherichia coli, in the absence and presence of cyanocobalamin (vitamin B(12)). In these structures, the Ton box is ordered and undergoes a conformational change in the presence of bound substrate. Calcium has been implicated as a necessary factor for the high-affinity binding (K(d) approximately 0.3 nM) of cyanocobalamin to BtuB. We observe two bound calcium ions that order three extracellular loops of BtuB, thus providing a direct (and unusual) structural role for calcium.
About this StructureAbout this Structure
1NQE is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
ReferenceReference
Substrate-induced transmembrane signaling in the cobalamin transporter BtuB., Chimento DP, Mohanty AK, Kadner RJ, Wiener MC, Nat Struct Biol. 2003 May;10(5):394-401. PMID:12652322
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