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==Cycloisomaltooligosaccharide binding protein in complex with isomaltoheptaose==
<StructureSection load='9xfu' size='340' side='right'caption='[[9xfu]], [[Resolution|resolution]] 1.90&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[9xfu]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Bacillaceae Bacillaceae]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=9XFU OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=9XFU 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]] 1.9&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=GLC:ALPHA-D-GLUCOSE'>GLC</scene></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=9xfu FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=9xfu OCA], [https://pdbe.org/9xfu PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=9xfu RCSB], [https://www.ebi.ac.uk/pdbsum/9xfu PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=9xfu ProSAT]</span></td></tr>
</table>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
ATP-binding cassette (ABC) transporters facilitate the translocation of various substrates across biological membranes. In prokaryotic ABC importers, solute binding protein (SBP), which selectively binds to a ligand, is incorporated into the functional complex. Cycloisomaltooligosaccharides (CIs) are produced from alpha-(1--&gt;6)-glucan by CI glucanotransferase, and intracellularly degraded by CI-inducible dextranase. CIs are regarded as incorporated forms; however, their uptake mechanisms have not yet been elucidated. In this study, SBP with a high affinity for CIs from Tepidibacillus decaturensis (TdCIBP) was discovered. TdCIBP showed the highest affinity for cycloisomaltoheptaose, followed by cycloisomaltooctaose and cycloisomaltononaose. TdCIBP also showed binding affinity for linear isomaltooligosaccharides with degree of polymerization &gt;/=3 but preferred longer isomaltooligosaccharides. TdCIBP structures in complex with cycloisomaltooctaose and isomaltoheptaose were determined using X-ray crystallography at 1.6 A and 1.9 A resolutions, respectively. Of the modeled five d-glucosyl residues in isomaltoheptaose, the two d-glucosyl residues (the third and fourth residues from the reducing end) were bound to TdCIBP through numerous hydrogen bonding interactions in the same orientation as the corresponding D-glucosyl residues of cycloisomaltooctaose. The other D-glucosyl residues of isomaltoheptaose bind differently to the binding site than the corresponding D-glucosyl residues of cycloisomaltooctaose. As little difference was observed in the amino acid orientation of TdCIBP between the two complexes, cyclic and linear isomaltooligosaccharides were bound to TdCIBP by changing the combination of interacting amino acid residues. The high affinity to CIs and long isomaltooligosaccharides suggests that the ABC transporter cooperating with TdCIBP uptakes these sugars directly, contributing to sugar metabolism and minimizing ATP consumption.

Insights into the recognition of cyclic alpha-(1--&gt;6)-glucan by a solute-binding protein of an ABC transporter from Tepidibacillus decaturensis.,Takei S, Saburi W, Yao M, Mori H, Ose T J Biol Chem. 2026 Mar 4:111346. doi: 10.1016/j.jbc.2026.111346. PMID:41791706<ref>PMID:41791706</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 9xfu" style="background-color:#fffaf0;"></div>
== References ==
<references/>
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</StructureSection>
[[Category: Bacillaceae]]
[[Category: Large Structures]]
[[Category: Mori H]]
[[Category: Ose T]]
[[Category: Saburi W]]
[[Category: Takei S]]
[[Category: Yao M]]