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6ayk

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Crystal structure of TEM1 beta-lactamase mutant I263A in the presence of 1.2 MPa xenon

Structural highlights

6ayk is a 4 chain structure with sequence from Escherichia coli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 1.44Å
Ligands:
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

BLAT_ECOLX TEM-type are the most prevalent beta-lactamases in enterobacteria; they hydrolyze the beta-lactam bond in susceptible beta-lactam antibiotics, thus conferring resistance to penicillins and cephalosporins. TEM-3 and TEM-4 are capable of hydrolyzing cefotaxime and ceftazidime. TEM-5 is capable of hydrolyzing ceftazidime. TEM-6 is capable of hydrolyzing ceftazidime and aztreonam. TEM-8/CAZ-2, TEM-16/CAZ-7 and TEM-24/CAZ-6 are markedly active against ceftazidime. IRT-4 shows resistance to beta-lactamase inhibitors.

Publication Abstract from PubMed

Genetically encoded (GE) contrast agents detectable by magnetic resonance imaging (MRI) enable non-invasive visualization of gene expression and cell proliferation at virtually unlimited penetration depths. Using hyperpolarized (129) Xe in combination with chemical exchange saturation transfer, an MR contrast approach known as hyper-CEST, enables ultrasensitive protein detection and biomolecular imaging. GE MRI contrast agents developed to date include nanoscale proteinaceous gas vesicles as well as the monomeric bacterial proteins TEM-1 beta-lactamase (bla) and maltose binding protein (MBP). To improve understanding of hyper-CEST NMR with proteins, structural and computational studies were performed to further characterize the Xe-bla interaction. X-ray crystallography validated the location of a high-occupancy Xe binding site predicted by MD simulations, and mutagenesis experiments confirmed this Xe site as the origin of the observed CEST contrast. Structural studies and MD simulations with representative bla mutants offered additional insight regarding the relationship between local protein structure and CEST contrast.

A Structural Basis for (129) Xe Hyper-CEST Signal in TEM-1 beta-Lactamase.,Roose BW, Zemerov SD, Wang Y, Kasimova MA, Carnevale V, Dmochowski IJ Chemphyschem. 2018 Aug 27. doi: 10.1002/cphc.201800624. PMID:30151973^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Roose BW, Zemerov SD, Wang Y, Kasimova MA, Carnevale V, Dmochowski IJ. A Structural Basis for (129) Xe Hyper-CEST Signal in TEM-1 beta-Lactamase. Chemphyschem. 2018 Aug 27. doi: 10.1002/cphc.201800624. PMID:30151973 doi:http://dx.doi.org/10.1002/cphc.201800624