1anf: Difference between revisions

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MALTODEXTRIN BINDING PROTEIN WITH BOUND MALTOSE

OverviewOverview

BACKGROUND: Active-transport processes perform a vital function in the life of a cell, maintaining cell homeostasis and allowing access of nutrients. Maltodextrin/maltose-binding protein (MBP; M(r) = 40k) is a receptor protein which serves as an initial high-affinity binding component of the active-transport system of maltooligosaccharides in bacteria. MBP also participates in chemotaxis towards maltooligosaccharides. The interaction between MBP and specific cytoplasmic membrane proteins initiates either active transport or chemotaxis. In order to gain new understanding of the function of MBP, especially its versatility in binding different linear and cyclic oligosaccharides with similar affinities, we have undertaken high-resolution X-ray analysis of three oligosaccharide-bound structures. RESULTS: The structures of MBP complexed with maltose, maltotriose and maltotetraose have been refined to high resolutions (1.67 to 1.8 A). These structures provide details at the atomic level of many features of oligosaccharide binding. The structures reveal differences between buried and surface binding sites and show the importance of hydrogen bonds and van der Waals interactions, especially those resulting from aromatic residue stacking. Insights are provided into the structural plasticity of the protein, the binding affinity and the binding specificity with respect to alpha/beta anomeric preference and oligosaccharide length. In addition, the structures demonstrate the different conformations that can be adopted by the oligosaccharide within the complex. CONCLUSIONS: MBP has a two-domain structure joined by a hinge-bending region which contains the substrate-binding groove. The bound maltooligosaccharides have a ribbon-like structure: the edges of the ribbon are occupied by polar hydroxyl groups and the flat surfaces are composed of nonpolar patches of the sugar ring faces. The polar groups and nonpolar patches are heavily involved in forming hydrogen bonds and van der Waals contacts, respectively, with complimentary residues in the groove. Hinge-bending between the two domains enables the participation of both domains in the binding and sequestering of the oligosaccharides. Changes in the subtle contours of the binding site allow binding of maltodextrins of varying length with similarly high affinities. The fact that the three bound structures are essentially identical ensures productive interaction with the oligomeric membrane proteins, which are distinct for transport and chemotaxis.

About this StructureAbout this Structure

1ANF is a Single protein structure of sequence from Escherichia coli. This structure supersedes the now removed PDB entries 2MBP and 1MBP. Full crystallographic information is available from OCA.

ReferenceReference

Extensive features of tight oligosaccharide binding revealed in high-resolution structures of the maltodextrin transport/chemosensory receptor., Quiocho FA, Spurlino JC, Rodseth LE, Structure. 1997 Aug 15;5(8):997-1015. PMID:9309217

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-[[Image:1anf.gif|left|200px]]<br /><applet load="1anf" size="450" color="white" frame="true" align="right" spinBox="true"
+[[Image:1anf.gif|left|200px]]<br /><applet load="1anf" size="350" color="white" frame="true" align="right" spinBox="true"
 caption="1anf, resolution 1.67&Aring;" />
 '''MALTODEXTRIN BINDING PROTEIN WITH BOUND MALTOSE'''<br />
 ==Overview==
-BACKGROUND: Active-transport processes perform a vital function in the, life of a cell, maintaining cell homeostasis and allowing access of, nutrients. Maltodextrin/maltose-binding protein (MBP; M(r) = 40k) is a, receptor protein which serves as an initial high-affinity binding, component of the active-transport system of maltooligosaccharides in, bacteria. MBP also participates in chemotaxis towards, maltooligosaccharides. The interaction between MBP and specific, cytoplasmic membrane proteins initiates either active transport or, chemotaxis. In order to gain new understanding of the function of MBP, especially its versatility in binding different linear and cyclic, oligosaccharides with similar affinities, we have undertaken, high-resolution X-ray analysis of three oligosaccharide-bound structures., RESULTS: The structures of MBP complexed with maltose, maltotriose and, maltotetraose have been refined to high resolutions (1.67 to 1.8 A). These, structures provide details at the atomic level of many features of, oligosaccharide binding. The structures reveal differences between buried, and surface binding sites and show the importance of hydrogen bonds and, van der Waals interactions, especially those resulting from aromatic, residue stacking. Insights are provided into the structural plasticity of, the protein, the binding affinity and the binding specificity with respect, to alpha/beta anomeric preference and oligosaccharide length. In addition, the structures demonstrate the different conformations that can be adopted, by the oligosaccharide within the complex. CONCLUSIONS: MBP has a, two-domain structure joined by a hinge-bending region which contains the, substrate-binding groove. The bound maltooligosaccharides have a, ribbon-like structure: the edges of the ribbon are occupied by polar, hydroxyl groups and the flat surfaces are composed of nonpolar patches of, the sugar ring faces. The polar groups and nonpolar patches are heavily, involved in forming hydrogen bonds and van der Waals contacts, respectively, with complimentary residues in the groove. Hinge-bending, between the two domains enables the participation of both domains in the, binding and sequestering of the oligosaccharides. Changes in the subtle, contours of the binding site allow binding of maltodextrins of varying, length with similarly high affinities. The fact that the three bound, structures are essentially identical ensures productive interaction with, the oligomeric membrane proteins, which are distinct for transport and, chemotaxis.
+BACKGROUND: Active-transport processes perform a vital function in the life of a cell, maintaining cell homeostasis and allowing access of nutrients. Maltodextrin/maltose-binding protein (MBP; M(r) = 40k) is a receptor protein which serves as an initial high-affinity binding component of the active-transport system of maltooligosaccharides in bacteria. MBP also participates in chemotaxis towards maltooligosaccharides. The interaction between MBP and specific cytoplasmic membrane proteins initiates either active transport or chemotaxis. In order to gain new understanding of the function of MBP, especially its versatility in binding different linear and cyclic oligosaccharides with similar affinities, we have undertaken high-resolution X-ray analysis of three oligosaccharide-bound structures. RESULTS: The structures of MBP complexed with maltose, maltotriose and maltotetraose have been refined to high resolutions (1.67 to 1.8 A). These structures provide details at the atomic level of many features of oligosaccharide binding. The structures reveal differences between buried and surface binding sites and show the importance of hydrogen bonds and van der Waals interactions, especially those resulting from aromatic residue stacking. Insights are provided into the structural plasticity of the protein, the binding affinity and the binding specificity with respect to alpha/beta anomeric preference and oligosaccharide length. In addition, the structures demonstrate the different conformations that can be adopted by the oligosaccharide within the complex. CONCLUSIONS: MBP has a two-domain structure joined by a hinge-bending region which contains the substrate-binding groove. The bound maltooligosaccharides have a ribbon-like structure: the edges of the ribbon are occupied by polar hydroxyl groups and the flat surfaces are composed of nonpolar patches of the sugar ring faces. The polar groups and nonpolar patches are heavily involved in forming hydrogen bonds and van der Waals contacts, respectively, with complimentary residues in the groove. Hinge-bending between the two domains enables the participation of both domains in the binding and sequestering of the oligosaccharides. Changes in the subtle contours of the binding site allow binding of maltodextrins of varying length with similarly high affinities. The fact that the three bound structures are essentially identical ensures productive interaction with the oligomeric membrane proteins, which are distinct for transport and chemotaxis.
 ==About this Structure==
-ANF is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. This structure superseeds the now removed PDB entries 2MBP and 1MBP. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1ANF OCA].
+ANF is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. This structure supersedes the now removed PDB entries 2MBP and 1MBP. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1ANF OCA].
 ==Reference==
@@ Line 13: / Line 13: @@
 [[Category: Escherichia coli]]
 [[Category: Single protein]]
-[[Category: Quiocho, F.A.]]
+[[Category: Quiocho, F A.]]
-[[Category: Spurlino, J.C.]]
+[[Category: Spurlino, J C.]]
 [[Category: periplasmic binding protein]]
 [[Category: sugar transport]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Tue Nov 20 10:59:03 2007''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 11:46:21 2008''