3bti

<StructureSection load='3bti' size='340' side='right' caption='[[3bti]], [[Resolution|resolution]] 2.85&Aring;' scene=''>

<table><tr><td colspan='2'>[[3bti]] is a 4 chain structure with sequence from [http://en.wikipedia.org/wiki/Staphylococcus_aureus Staphylococcus aureus]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=3BTI OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3BTI FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=BER:BERBERINE'>BER</scene>, <scene name='pdbligand=SO4:SULFATE+ION'>SO4</scene></td></tr>

<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[1jum|1jum]], [[3bt9|3bt9]], [[3btc|3btc]], [[1jup|1jup]], [[1jty|1jty]], [[1rkw|1rkw]], [[3btj|3btj]]</td></tr>

<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">qacR ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=1280 Staphylococcus aureus])</td></tr>

<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=3bti FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=3bti OCA], [http://pdbe.org/3bti PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=3bti RCSB], [http://www.ebi.ac.uk/pdbsum/3bti PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=3bti ProSAT]</span></td></tr>

[[http://www.uniprot.org/uniprot/QACR_STAAM 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).

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== 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.

 

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== References ==

[[Category: Staphylococcus aureus]]

[[Category: Brennan, R G]]

[[Category: Schumacher, M A]]

[[Category: Schuman, J T]]

[[Category: Berberine]]

[[Category: Transcription regulation]]