View source for 9e33


==Polaromonas naphthalenivorans phosphoenolpyruvate carboxykinase in complex with PEP (C2221)==
<StructureSection load='9e33' size='340' side='right'caption='[[9e33]], [[Resolution|resolution]] 1.74&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[9e33]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Polaromonas_naphthalenivorans Polaromonas naphthalenivorans]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=9E33 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=9E33 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]] 1.74&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=MN:MANGANESE+(II)+ION'>MN</scene>, <scene name='pdbligand=PEP:PHOSPHOENOLPYRUVATE'>PEP</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=9e33 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=9e33 OCA], [https://pdbe.org/9e33 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=9e33 RCSB], [https://www.ebi.ac.uk/pdbsum/9e33 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=9e33 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/A1VIE9_POLNA A1VIE9_POLNA] Catalyzes the conversion of oxaloacetate (OAA) to phosphoenolpyruvate (PEP), the rate-limiting step in the metabolic pathway that produces glucose from lactate and other precursors derived from the citric acid cycle.[HAMAP-Rule:MF_00452]
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Temperature is a critical factor in enzyme function, as most enzymes are thermally activated. Across Earth's diverse environments (-20 to 120 degrees C), enzymes have evolved to function optimally at their organism's growth temperature. Thermophilic enzymes must resist denaturation, while psychrophilic enzymes must maintain activity with limited thermal energy. Although principles underlying thermostability are well established, the mechanisms governing kinetic adaptation to temperature remain less understood. To investigate this, we characterized the kinetics and determined a comprehensive series of X-ray crystal structures of a psychrophilic, GTP-dependent phosphoenolpyruvate carboxykinase (PEPCK) bound to substrates and non-reactive mimics of the reaction coordinate. These structures were compared to those of a mesophilic PEPCK. PEPCK is a dynamic enzyme requiring substantial conformational changes during catalysis, particularly ordering of the active site Omega-loop lid. The psychrophilic enzyme exhibited a reduced catalytic efficiency (k(cat)/K(M)) and lower optimal temperature (T(opt)) relative to its mesophilic counterpart. Structural comparisons revealed substitutions in the Omega-loop that likely increase the entropic cost of loop ordering and reduce enthalpic stabilization, hindering efficient active site closure. These results provide a mechanistic basis for cold adaptation in enzyme catalysis, linking specific structural features to altered kinetic behavior. Understanding such adaptations not only advances our knowledge of enzyme evolution but also informs protein engineering efforts aimed at designing efficient biocatalysts for industrial applications operating at non-physiological temperatures.

Structural mechanisms for cold-adapted activity of phosphoenolpyruvate carboxykinase.,McLeod MJ, Yazdani S, Barwell SAE, Holyoak T Protein Sci. 2025 Nov;34(11):e70326. doi: 10.1002/pro.70326. PMID:41099612<ref>PMID:41099612</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 9e33" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Polaromonas naphthalenivorans]]
[[Category: Barwell SAE]]
[[Category: Holyoak T]]
[[Category: McLeod MJ]]