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[[Image:1peb.jpg|left|200px]]
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{{STRUCTURE_1peb|  PDB=1peb  |  SCENE=  }}
'''LIGAND-FREE HIGH-AFFINITY MALTOSE-BINDING PROTEIN'''


==LIGAND-FREE HIGH-AFFINITY MALTOSE-BINDING PROTEIN==
<StructureSection load='1peb' size='340' side='right'caption='[[1peb]], [[Resolution|resolution]] 2.60&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1peb]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1PEB OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1PEB FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.6&#8491;</td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1peb FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1peb OCA], [https://pdbe.org/1peb PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1peb RCSB], [https://www.ebi.ac.uk/pdbsum/1peb PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1peb ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/MALE_ECOLI MALE_ECOLI] Involved in the high-affinity maltose membrane transport system MalEFGK. Initial receptor for the active transport of and chemotaxis toward maltooligosaccharides.
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/pe/1peb_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=1peb ConSurf].
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The affinity of maltose-binding protein (MBP) for maltose and related carbohydrates was greatly increased by removal of groups in the interface opposite the ligand binding cleft. The wild-type protein has a KD of 1200 nM for maltose; mutation of residues Met-321 and Gln-325, both to alanine, resulted in a KD for maltose of 70 nM; deletion of 4 residues, Glu-172, Asn-173, Lys-175, and Tyr-176, which are part of a poorly ordered loop, results in a KD for maltose of 110 nM. Combining the mutations yields an increased affinity for maltodextrins and a KD of 6 nM for maltotriose. Comparison of ligand binding by the mutants, using surface plasmon resonance spectroscopy, indicates that decreases in the off-rate are responsible for the increased affinity. Small-angle x-ray scattering was used to demonstrate that the mutations do not significantly affect the solution conformation of MBP in either the presence or absence of maltose. The crystal structures of selected mutants showed that the mutations do not cause significant structural changes in either the closed or open conformation of MBP. These studies show that interactions in the interface opposite the ligand binding cleft, which we term the "balancing interface," are responsible for modulating the affinity of MBP for its ligand. Our results are consistent with a model in which the ligand-bound protein alternates between the closed and open conformations, and removal of interactions in the balancing interface decreases the stability of the open conformation, without affecting the closed conformation.


==Overview==
Insights into the conformational equilibria of maltose-binding protein by analysis of high affinity mutants.,Telmer PG, Shilton BH J Biol Chem. 2003 Sep 5;278(36):34555-67. Epub 2003 Jun 6. PMID:12794084<ref>PMID:12794084</ref>
The affinity of maltose-binding protein (MBP) for maltose and related carbohydrates was greatly increased by removal of groups in the interface opposite the ligand binding cleft. The wild-type protein has a KD of 1200 nM for maltose; mutation of residues Met-321 and Gln-325, both to alanine, resulted in a KD for maltose of 70 nM; deletion of 4 residues, Glu-172, Asn-173, Lys-175, and Tyr-176, which are part of a poorly ordered loop, results in a KD for maltose of 110 nM. Combining the mutations yields an increased affinity for maltodextrins and a KD of 6 nM for maltotriose. Comparison of ligand binding by the mutants, using surface plasmon resonance spectroscopy, indicates that decreases in the off-rate are responsible for the increased affinity. Small-angle x-ray scattering was used to demonstrate that the mutations do not significantly affect the solution conformation of MBP in either the presence or absence of maltose. The crystal structures of selected mutants showed that the mutations do not cause significant structural changes in either the closed or open conformation of MBP. These studies show that interactions in the interface opposite the ligand binding cleft, which we term the "balancing interface," are responsible for modulating the affinity of MBP for its ligand. Our results are consistent with a model in which the ligand-bound protein alternates between the closed and open conformations, and removal of interactions in the balancing interface decreases the stability of the open conformation, without affecting the closed conformation.


==About this Structure==
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
1PEB 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=1PEB OCA].
</div>
<div class="pdbe-citations 1peb" style="background-color:#fffaf0;"></div>


==Reference==
==See Also==
Insights into the conformational equilibria of maltose-binding protein by analysis of high affinity mutants., Telmer PG, Shilton BH, J Biol Chem. 2003 Sep 5;278(36):34555-67. Epub 2003 Jun 6. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/12794084 12794084]
*[[Maltose-binding protein 3D structures|Maltose-binding protein 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia coli]]
[[Category: Escherichia coli]]
[[Category: Single protein]]
[[Category: Large Structures]]
[[Category: Shilton, B H.]]
[[Category: Shilton BH]]
[[Category: Telmer, P G.]]
[[Category: Telmer PG]]
[[Category: Engineered]]
[[Category: High-affinity mutant]]
[[Category: Maltose-binding protein]]
[[Category: Mbp]]
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May  3 04:59:32 2008''
Retrieved from "https://proteopedia.org/1peb"