View source for 8tn0


==Crystal structure of KPC-44 carbapenemase w/o cryoprotectant==
<StructureSection load='8tn0' size='340' side='right'caption='[[8tn0]], [[Resolution|resolution]] 1.31&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[8tn0]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Klebsiella_pneumoniae Klebsiella pneumoniae]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=8TN0 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=8TN0 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]] 1.31&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=SO4:SULFATE+ION'>SO4</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=8tn0 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=8tn0 OCA], [https://pdbe.org/8tn0 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=8tn0 RCSB], [https://www.ebi.ac.uk/pdbsum/8tn0 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=8tn0 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/A0A4Y5JTU1_KLEPN A0A4Y5JTU1_KLEPN] 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Klebsiella pneumoniae carbapenemase 2 (KPC-2) is an important source of drug resistance as it can hydrolyze and inactivate virtually all beta-lactam antibiotics. KPC-2 is potently inhibited by avibactam via formation of a reversible carbamyl linkage of the inhibitor with the catalytic serine of the enzyme. However, the use of avibactam in combination with ceftazidime (CAZ-AVI) has led to the emergence of CAZ-AVI-resistant variants of KPC-2 in clinical settings. One such variant, KPC-44, bears a 15 amino acid duplication in one of the active-site loops (270-loop). Here, we show that the KPC-44 variant exhibits higher catalytic efficiency in hydrolyzing ceftazidime, lower efficiency toward imipenem and meropenem, and a similar efficiency in hydrolyzing ampicillin, than the WT KPC-2 enzyme. In addition, the KPC-44 variant enzyme exhibits 12-fold lower AVI carbamylation efficiency than the KPC-2 enzyme. An X-ray crystal structure of KPC-44 showed that the 15 amino acid duplication results in an extended and partially disordered 270-loop and also changes the conformation of the adjacent 240-loop, which in turn has altered interactions with the active-site omega loop. Furthermore, a structure of KPC-44 with avibactam revealed that formation of the covalent complex results in further disorder in the 270-loop, suggesting that rearrangement of the 270-loop of KPC-44 facilitates AVI carbamylation. These results suggest that the duplication of 15 amino acids in the KPC-44 enzyme leads to resistance to CAZ-AVI by modulating the stability and conformation of the 270-, 240-, and omega-loops.

Klebsiella pneumoniae carbapenemase variant 44 acquires ceftazidime-avibactam resistance by altering the conformation of active-site loops.,Sun Z, Lin H, Hu L, Neetu N, Sankaran B, Wang J, Prasad BVV, Palzkill T J Biol Chem. 2024 Jan;300(1):105493. doi: 10.1016/j.jbc.2023.105493. Epub 2023 , Nov 23. PMID:38000656<ref>PMID:38000656</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 8tn0" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Klebsiella pneumoniae]]
[[Category: Large Structures]]
[[Category: Hu L]]
[[Category: Lin H]]
[[Category: Palzkill T]]
[[Category: Prasad B]]
[[Category: Sankaran B]]
[[Category: Sun Z]]
[[Category: Wang J]]