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1qvu

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Crystal structure of the multidrug binding transcriptional repressor QacR bound to two drugs: ethidium and proflavine

Structural highlights

1qvu is a 4 chain structure with sequence from Staphylococcus aureus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 2.96Å
Ligands:	,
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

QACR_STAAU Transcriptional repressor of qacA. Binds to IR1, an unusually long 28 bp operator, which is located downstream from the qacA promoter and overlaps its transcription start site. QacR is induced from its IR1 site by binding to one of many structurally dissimilar cationic lipophilic compounds, which are also substrates of QacA.

Evolutionary Conservation

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

Publication Abstract from PubMed

The structural basis of simultaneous binding of two or more different drugs by any multidrug-binding protein is unknown and also how this can lead to a noncompetitive, uncompetitive or cooperative binding mechanism. Here, we describe the crystal structure of the Staphylococcus aureus multidrug-binding transcription repressor, QacR, bound simultaneously to ethidium (Et) and proflavin (Pf). The structure underscores the plasticity of the multidrug-binding pocket and reveals an alternative, Pf-induced binding mode for Et. To monitor the simultaneous binding of Pf and Et to QacR, as well as to determine the effects on the binding affinity of one drug when the other drug is prebound, a novel application of near-ultraviolet circular dichroism (UVCD) was developed. The UVCD equilibrium-binding studies revealed identical affinities of Pf for QacR in the presence or absence of Et, but significantly diminished affinity of Et for QacR when Pf is prebound, findings that are readily explicable by their structures. The principles for simultaneous binding of two different drugs discerned here are likely employed by the multidrug efflux transporters.

Structural mechanism of the simultaneous binding of two drugs to a multidrug-binding protein.,Schumacher MA, Miller MC, Brennan RG EMBO J. 2004 Aug 4;23(15):2923-30. Epub 2004 Jul 15. PMID:15257299^[1]

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

References

↑ Schumacher MA, Miller MC, Brennan RG. Structural mechanism of the simultaneous binding of two drugs to a multidrug-binding protein. EMBO J. 2004 Aug 4;23(15):2923-30. Epub 2004 Jul 15. PMID:15257299 doi:http://dx.doi.org/10.1038/sj.emboj.7600288