2b4l
From Proteopedia
(New page: 200px<br /><applet load="2b4l" size="450" color="white" frame="true" align="right" spinBox="true" caption="2b4l, resolution 2.00Å" /> '''Crystal structure of...) |
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| - | [[Image:2b4l.gif|left|200px]]<br /><applet load="2b4l" size=" | + | [[Image:2b4l.gif|left|200px]]<br /><applet load="2b4l" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="2b4l, resolution 2.00Å" /> | caption="2b4l, resolution 2.00Å" /> | ||
'''Crystal structure of the binding protein OpuAC in complex with glycine betaine'''<br /> | '''Crystal structure of the binding protein OpuAC in complex with glycine betaine'''<br /> | ||
==Overview== | ==Overview== | ||
| - | Compatible solutes play a decisive role in the defense of microorganisms | + | Compatible solutes play a decisive role in the defense of microorganisms against changes in temperature and increases in osmolarity in their natural habitats. In Bacillus subtilis, the substrate-binding protein (SBP)-dependent ABC-transporter OpuA serves for the uptake of the compatible solutes glycine betaine (GB) and proline betaine (PB). Here, we report the determinants of compatible solute binding by OpuAC, the SBP of the OpuA transporter, by equilibrium binding studies and X-ray crystallography. The affinity of OpuAC/GB and OpuAC/PB complexes were analyzed by intrinsic tryptophan fluorescence and the K(D) values were determined to be 17(+/-1)microM for GB and 295(+/-27)microM for PB, respectively. The structures of OpuAC in complex with GB or PB were solved at 2.0 A and 2.8 A, respectively, and show an SBP-typical class II fold. The ligand-binding pocket is formed by three tryptophan residues arranged in a prism-like geometry suitable to coordinate the positive charge of the trimethyl ammonium group of GB and the dimethyl ammonium group of PB by cation-pi interactions and by hydrogen bonds with the carboxylate moiety of the ligand. Structural differences between the OpuAC/GB and OpuAC/PB complexes occur within the ligand-binding pocket as well as across the domain-domain interface. These differences provide a structural framework to explain the drastic differences in affinity of the OpuAC/GB and OpuAC/PB complexes. A sequence comparison with putative SBP specific for compatible solutes reveals the presence of three distinct families for which the crystal structure of OpuAC might serve as a suitable template to predict the structures of these putative compatible solute-binding proteins. |
==About this Structure== | ==About this Structure== | ||
| - | 2B4L is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacillus_subtilis Bacillus subtilis] with BET and EDO as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | + | 2B4L is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bacillus_subtilis Bacillus subtilis] with <scene name='pdbligand=BET:'>BET</scene> and <scene name='pdbligand=EDO:'>EDO</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2B4L OCA]. |
==Reference== | ==Reference== | ||
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[[Category: substrate-binding protein]] | [[Category: substrate-binding protein]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:34:06 2008'' |
Revision as of 14:34, 21 February 2008
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Crystal structure of the binding protein OpuAC in complex with glycine betaine
Overview
Compatible solutes play a decisive role in the defense of microorganisms against changes in temperature and increases in osmolarity in their natural habitats. In Bacillus subtilis, the substrate-binding protein (SBP)-dependent ABC-transporter OpuA serves for the uptake of the compatible solutes glycine betaine (GB) and proline betaine (PB). Here, we report the determinants of compatible solute binding by OpuAC, the SBP of the OpuA transporter, by equilibrium binding studies and X-ray crystallography. The affinity of OpuAC/GB and OpuAC/PB complexes were analyzed by intrinsic tryptophan fluorescence and the K(D) values were determined to be 17(+/-1)microM for GB and 295(+/-27)microM for PB, respectively. The structures of OpuAC in complex with GB or PB were solved at 2.0 A and 2.8 A, respectively, and show an SBP-typical class II fold. The ligand-binding pocket is formed by three tryptophan residues arranged in a prism-like geometry suitable to coordinate the positive charge of the trimethyl ammonium group of GB and the dimethyl ammonium group of PB by cation-pi interactions and by hydrogen bonds with the carboxylate moiety of the ligand. Structural differences between the OpuAC/GB and OpuAC/PB complexes occur within the ligand-binding pocket as well as across the domain-domain interface. These differences provide a structural framework to explain the drastic differences in affinity of the OpuAC/GB and OpuAC/PB complexes. A sequence comparison with putative SBP specific for compatible solutes reveals the presence of three distinct families for which the crystal structure of OpuAC might serve as a suitable template to predict the structures of these putative compatible solute-binding proteins.
About this Structure
2B4L is a Single protein structure of sequence from Bacillus subtilis with and as ligands. Full crystallographic information is available from OCA.
Reference
Molecular determinants for substrate specificity of the ligand-binding protein OpuAC from Bacillus subtilis for the compatible solutes glycine betaine and proline betaine., Horn C, Sohn-Bosser L, Breed J, Welte W, Schmitt L, Bremer E, J Mol Biol. 2006 Mar 24;357(2):592-606. Epub 2006 Jan 13. PMID:16445940
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