View source for 9xko


==High-resolution cryo-EM structure of Maltose Binding Protein==
<StructureSection load='9xko' size='340' side='right'caption='[[9xko]], [[Resolution|resolution]] 2.35&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[9xko]] 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=9XKO OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=9XKO FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Electron Microscopy, [[Resolution|Resolution]] 2.35&#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>, <scene name='pdbligand=PRD_900001:alpha-maltose'>PRD_900001</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=9xko FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=9xko OCA], [https://pdbe.org/9xko PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=9xko RCSB], [https://www.ebi.ac.uk/pdbsum/9xko PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=9xko 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.
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Cryo-electron microscopy (cryo-EM) is a widely used technique for determining macromolecular structures at near-atomic resolution. The theoretical lower limit of particle sizes suitable for cryo-EM structural analysis is estimated to be 38 kDa; typical constraints involve factors such as image contrast and particle alignment accuracy. In this study, we present cryo-EM structures of two protein-ligand complexes near this lower size threshold. First, the structure of the maltose-binding protein complexed with maltose, with a structurally ordered mass of 40.8 kDa, was determined at a resolution of 2.4 A; both the maltose and water molecules were clearly identified in this structure. The second structure was the kinase domain of human PLK1 complexed with onvansertib, with a structurally ordered mass of 31.6 kDa, below the theoretical 38 kDa limit; this domain was determined at a resolution of 3.4 A using a gold-supported grid in the presence of beta-octyl-glucoside. The density map clearly shows the backbone of PLK1 secondary structure, and the onvansertib. These results demonstrate that cryo-EM can be effectively employed to determine structures of small proteins or domains, and to perform structure-based drug screening for small proteins, without requiring structural fiducials for particle alignment.

High-resolution cryo-EM structures of small protein-ligand complexes near the theoretical size limit.,Park K, Yoo Y, Jeon H, Choi K, Kim H, Kwon E, Lim HH, Kim DY, No KT Nat Commun. 2026 Apr 14. doi: 10.1038/s41467-026-71934-7. PMID:41980966<ref>PMID:41980966</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 9xko" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia coli]]
[[Category: Large Structures]]
[[Category: Choi K]]
[[Category: Jeon H]]
[[Category: Kim DY]]
[[Category: Kwon E]]
[[Category: Lim H]]
[[Category: No KT]]
[[Category: Park K]]
[[Category: Yoo Y]]