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Crystal structure of a cooperative QacR-DNA complexCrystal structure of a cooperative QacR-DNA complex
Structural highlights
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 PubMedThe Staphylococcus aureus multidrug-binding protein QacR represses transcription of the qacA multidrug transporter gene and is induced by multiple structurally dissimilar drugs. QacR is a member of the TetR/CamR family of transcriptional regulators, which share highly homologous N-terminal DNA-binding domains connected to seemingly non-homologous ligand-binding domains. Unlike other TetR members, which bind approximately 15 bp operators, QacR recognizes an unusually long 28 bp operator, IR1, which it appears to bind cooperatively. To elucidate the DNA-binding mechanism of QacR, we determined the 2.90 A resolution crystal structure of a QacR-IR1 complex. Strikingly, our data reveal that the DNA recognition mode of QacR is distinct from TetR and involves the binding of a pair of QacR dimers. In this unique binding mode, recognition at each IR1 half-site is mediated by a complement of DNA contacts made by two helix-turn-helix motifs. The inferred cooperativity does not arise from cross-dimer protein-protein contacts, but from the global undertwisting and major groove widening elicited by the binding of two QacR dimers. Structural basis for cooperative DNA binding by two dimers of the multidrug-binding protein QacR.,Schumacher MA, Miller MC, Grkovic S, Brown MH, Skurray RA, Brennan RG EMBO J. 2002 Mar 1;21(5):1210-8. PMID:11867549[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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