3bt9

crystal structure of QacR(E57Q) bound to Dequalinium

spinqualitylabelsall models 3bt9, resolution 2.75Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3bt9 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. Ligands: DEQ, SO4 Related: 1jt6, 1jup, 1jus, 1jty, 1jum, 1qvt, 3btc, 3bti Gene: qacR (Staphylococcus aureus) Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [QACR_STAAM] 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 (By similarity). 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 Staphylococcus aureus multidrug binding protein QacR binds to a broad spectrum of structurally dissimilar cationic, lipophilic drugs. Our previous structural analyses suggested that five QacR glutamic acid residues are critical for charge neutralization and specification of certain drugs. For example, E57 and E58 interact with berberine and with one of the positively charged moieties of the bivalent drug dequalinium. Here we report the structural and biochemical effects of substituting E57 and E58 with alanine and glutamine. Unexpectedly, individual substitutions of these residues did not significantly affect QacR drug binding affinity. Structures of QacR(E57Q) and QacR(E58Q) bound to dequalinium indicated that E57 and E58 are redundant for charge neutralization. The most significant finding was that berberine was reoriented in the QacR multidrug binding pocket so that its positive charge was neutralized by side chain oxygen atoms and aromatic residues. Together, these data emphasize the remarkable versatility of the QacR multidrug binding pocket, illustrating that the capacity of QacR to bind myriad cationic drugs is largely governed by the presence in the pocket of a redundancy of polar, charged, and aromatic residues that are capable of electrostatic neutralization. QacR-cation recognition is mediated by a redundancy of residues capable of charge neutralization.,Peters KM, Schuman JT, Skurray RA, Brown MH, Brennan RG, Schumacher MA Biochemistry. 2008 Aug 5;47(31):8122-9. Epub 2008 Jul 11. PMID:18616285 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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