3m2k: Difference between revisions
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==Crystal Structure of fluorescein-labeled Class A -beta lactamase PenP in complex with cefotaxime== | |||
<StructureSection load='3m2k' size='340' side='right'caption='[[3m2k]], [[Resolution|resolution]] 3.50Å' scene=''> | |||
== Structural highlights == | |||
<table><tr><td colspan='2'>[[3m2k]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Bacillus_licheniformis Bacillus licheniformis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3M2K OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=3M2K 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]] 3.5Å</td></tr> | |||
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CEF:CEFOTAXIME,+C3+CLEAVED,+OPEN,+BOUND+FORM'>CEF</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=3m2k FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3m2k OCA], [https://pdbe.org/3m2k PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=3m2k RCSB], [https://www.ebi.ac.uk/pdbsum/3m2k PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=3m2k ProSAT]</span></td></tr> | |||
</table> | |||
== Function == | |||
[https://www.uniprot.org/uniprot/BLAC_BACLI BLAC_BACLI] | |||
<div style="background-color:#fffaf0;"> | |||
== Publication Abstract from PubMed == | |||
BACKGROUND: beta-lactamase conjugated with environment-sensitive fluorescein molecule to residue 166 on the Omega-loop near its catalytic site is a highly effective biosensor for beta-lactam antibiotics. Yet the molecular mechanism of such fluorescence-based biosensing is not well understood. RESULTS: Here we report the crystal structure of a Class A beta-lactamase PenP from Bacillus licheniformis 749/C with fluorescein conjugated at residue 166 after E166C mutation, both in apo form (PenP-E166Cf) and in covalent complex form with cefotaxime (PenP-E166Cf-cefotaxime), to illustrate its biosensing mechanism. In the apo structure the fluorescein molecule partially occupies the antibiotic binding site and is highly dynamic. In the PenP-E166Cf-cefatoxime complex structure the binding and subsequent acylation of cefotaxime to PenP displaces fluorescein from its original location to avoid steric clash. Such displacement causes the well-folded Omega-loop to become fully flexible and the conjugated fluorescein molecule to relocate to a more solvent exposed environment, hence enhancing its fluorescence emission. Furthermore, the fully flexible Omega-loop enables the narrow-spectrum PenP enzyme to bind cefotaxime in a mode that resembles the extended-spectrum beta-lactamase. CONCLUSIONS: Our structural studies indicate the biosensing mechanism of a fluorescein-labelled beta-lactamase. Such findings confirm our previous proposal based on molecular modelling and provide useful information for the rational design of beta-lactamase-based biosensor to detect the wide spectrum of beta-lactam antibiotics. The observation of increased Omega-loop flexibility upon conjugation of fluorophore may have the potential to serve as a screening tool for novel beta-lactamase inhibitors that target the Omega-loop and not the active site. | |||
Structural studies of the mechanism for biosensing antibiotics in a fluorescein-labeled beta-lactamase.,Wong WT, Au HW, Yap HK, Leung YC, Wong KY, Zhao Y BMC Struct Biol. 2011 Mar 28;11:15. doi: 10.1186/1472-6807-11-15. PMID:21443768<ref>PMID:21443768</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
</div> | |||
<div class="pdbe-citations 3m2k" style="background-color:#fffaf0;"></div> | |||
==See Also== | ==See Also== | ||
*[[Beta-lactamase|Beta-lactamase]] | *[[Beta-lactamase 3D structures|Beta-lactamase 3D structures]] | ||
== References == | |||
<references/> | |||
__TOC__ | |||
</StructureSection> | |||
[[Category: Bacillus licheniformis]] | [[Category: Bacillus licheniformis]] | ||
[[Category: | [[Category: Large Structures]] | ||
[[Category: Leung | [[Category: Leung YC]] | ||
[[Category: Wong | [[Category: Wong WT]] | ||
[[Category: Zhao | [[Category: Zhao YX]] | ||