|
|
| Line 1: |
Line 1: |
| - | ==TETRACYCLINE CHELATED MG2+-ION INITIATES HELIX UNWINDING FOR TET REPRESSOR INDUCTION==
| + | #REDIRECT [[4v2g]] This PDB entry is obsolete and replaced by 4v2g |
| - | <StructureSection load='1bjy' size='340' side='right' caption='[[1bjy]], [[Resolution|resolution]] 2.70Å' scene=''>
| + | |
| - | == Structural highlights ==
| + | |
| - | <table><tr><td colspan='2'>[[1bjy]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1BJY OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1BJY FirstGlance]. <br>
| + | |
| - | </td></tr><tr><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=CTC:7-CHLOROTETRACYCLINE'>CTC</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene><br>
| + | |
| - | <tr><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1bjy FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1bjy OCA], [http://www.rcsb.org/pdb/explore.do?structureId=1bjy RCSB], [http://www.ebi.ac.uk/pdbsum/1bjy PDBsum]</span></td></tr>
| + | |
| - | <table>
| + | |
| - | == Evolutionary Conservation ==
| + | |
| - | [[Image:Consurf_key_small.gif|200px|right]]
| + | |
| - | Check<jmol>
| + | |
| - | <jmolCheckbox>
| + | |
| - | <scriptWhenChecked>select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/bj/1bjy_consurf.spt"</scriptWhenChecked>
| + | |
| - | <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
| + | |
| - | <text>to colour the structure by Evolutionary Conservation</text>
| + | |
| - | </jmolCheckbox>
| + | |
| - | </jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/chain_selection.php?pdb_ID=2ata ConSurf].
| + | |
| - | <div style="clear:both"></div>
| + | |
| - | <div style="background-color:#fffaf0;">
| + | |
| - | == Publication Abstract from PubMed ==
| + | |
| - | The homodimeric tetracycline repressor (TetR) regulates resistance to the antibiotic tetracycline at the transcriptional level. TetR binds in the absence of Tc to palindromic operator sequences utilizing two helix-turn-helix (HTH) motifs. If the tetracycline-Mg2+ complex [MgTc]+ enters two identical binding tunnels buried within the TetR homodimer, a conformational change takes place, and the induced [TetR/[MgTc]+]2 complex releases operator DNA. To demonstrate the contribution of Mg2+ to [MgTc]+ binding and TetR induction, the Mg2+ concentration in the induced TetR homodimer was progressively reduced by addition of EDTA, resulting in two X-ray crystal structures of Mg2+-free and half-occupied TetR(D). Tc remains bound to the [MgTc]+-binding sites, despite the complete or partial absence of Mg2+. Together with inducer-free TetR(D), the structures were refined to between 2.2 and 2.7 A resolution and compared with fully induced TetR(D) in complex with two [MgTc]+. Each inducer binding tunnel has three constituent parts, one hydrophobic and two hydrophilic ones. One of the hydrophilic contact areas binds Tc by hydrogen bonding; the hydrophobic region correctly positions Tc and partially closes the entrance to the binding tunnel; the second hydrophilic region coordinates Mg2+, transduces the induction signal, and completes the process of closing the tunnel entrance. Tc confers binding specificity to TetR while Mg2+ is primarily responsible for induction: After binding to the imidazole Nepsilon of His100, Mg2+ is octahedrally coordinated to the 1,3-ketoenolate group of Tc and to three water molecules. One of these waters forms a hydrogen bond to the hydroxyl group Ogamma of Thr103. The induced 2.5 A movement of Thr103 results in the partial unwinding of helix alpha6, associated with a lateral shift of helices alpha4 and alpha9. They simultaneously close the tunnel entrance and cause the DNA-binding domains to adopt a nonbinding conformation, leading to release of operator DNA and expression of the genes responsible for resistance.
| + | |
| - | | + | |
| - | Tetracycline-chelated Mg2+ ion initiates helix unwinding in Tet repressor induction.,Orth P, Saenger W, Hinrichs W Biochemistry. 1999 Jan 5;38(1):191-8. PMID:9890898<ref>PMID:9890898</ref>
| + | |
| - | | + | |
| - | From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br>
| + | |
| - | </div>
| + | |
| - | | + | |
| - | ==See Also==
| + | |
| - | *[[Tetracycline repressor protein|Tetracycline repressor protein]]
| + | |
| - | == References ==
| + | |
| - | <references/>
| + | |
| - | __TOC__
| + | |
| - | </StructureSection>
| + | |
| - | [[Category: Escherichia coli]]
| + | |
| - | [[Category: Hinrichs, W.]]
| + | |
| - | [[Category: Orth, P.]]
| + | |
| - | [[Category: Saenger, W.]]
| + | |
| - | [[Category: Dna-binding protein]]
| + | |
| - | [[Category: Hth-motif]]
| + | |
| - | [[Category: Transcription regulation]]
| + | |
