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==CRYSTAL STRUCTURE OF THE LACI FAMILY MEMBER, PURR, BOUND TO DNA: MINOR GROOVE BINDING BY ALPHA HELICES==
==CRYSTAL STRUCTURE OF THE LACI FAMILY MEMBER, PURR, BOUND TO DNA: MINOR GROOVE BINDING BY ALPHA HELICES==
<StructureSection load='2pue' size='340' side='right' caption='[[2pue]], [[Resolution|resolution]] 2.70&Aring;' scene=''>
<StructureSection load='2pue' size='340' side='right'caption='[[2pue]], [[Resolution|resolution]] 2.70&Aring;' scene=''>
== Structural highlights ==
== Structural highlights ==
<table><tr><td colspan='2'>[[2pue]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/"bacillus_coli"_migula_1895 "bacillus coli" migula 1895]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2PUE OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=2PUE FirstGlance]. <br>
<table><tr><td colspan='2'>[[2pue]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2PUE OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2PUE FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=ADE:ADENINE'>ADE</scene></td></tr>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.7&#8491;</td></tr>
<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">PURR ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=562 "Bacillus coli" Migula 1895])</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ADE:ADENINE'>ADE</scene></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=2pue FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2pue OCA], [http://pdbe.org/2pue PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=2pue RCSB], [http://www.ebi.ac.uk/pdbsum/2pue PDBsum]</span></td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=2pue FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2pue OCA], [https://pdbe.org/2pue PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2pue RCSB], [https://www.ebi.ac.uk/pdbsum/2pue PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2pue ProSAT]</span></td></tr>
</table>
</table>
== Function ==
== Function ==
[[http://www.uniprot.org/uniprot/PURR_ECOLI PURR_ECOLI]] Is the main repressor of the genes involved in the de novo synthesis of purine nucleotides, regulating purB, purC, purEK, purF, purHD, purL, purMN and guaBA expression. In addition, it participates in the regulation or coregulation of genes involved in de novo pyrimidine nucleotide biosynthesis, salvage and uptake (pyrC, pyrD, carAB and codBA), and of several genes encoding enzymes necessary for nucleotide and polyamine biosynthesis (prsA, glyA, gcvTHP, speA, glnB). Binds to a 16-bp palindromic sequence located within the promoter region of pur regulon genes. The consensus binding sequence is 5'-ACGCAAACGTTTTCNT-3'. PurR is allosterically activated to bind its cognate DNA by binding the purine corepressors, hypoxanthine or guanine, thereby effecting transcription repression.<ref>PMID:2404765</ref> <ref>PMID:2211500</ref> <ref>PMID:1400170</ref> <ref>PMID:14741201</ref>
[https://www.uniprot.org/uniprot/PURR_ECOLI PURR_ECOLI] Is the main repressor of the genes involved in the de novo synthesis of purine nucleotides, regulating purB, purC, purEK, purF, purHD, purL, purMN and guaBA expression. In addition, it participates in the regulation or coregulation of genes involved in de novo pyrimidine nucleotide biosynthesis, salvage and uptake (pyrC, pyrD, carAB and codBA), and of several genes encoding enzymes necessary for nucleotide and polyamine biosynthesis (prsA, glyA, gcvTHP, speA, glnB). Binds to a 16-bp palindromic sequence located within the promoter region of pur regulon genes. The consensus binding sequence is 5'-ACGCAAACGTTTTCNT-3'. PurR is allosterically activated to bind its cognate DNA by binding the purine corepressors, hypoxanthine or guanine, thereby effecting transcription repression.<ref>PMID:2404765</ref> <ref>PMID:2211500</ref> <ref>PMID:1400170</ref> <ref>PMID:14741201</ref>  
== Evolutionary Conservation ==
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
Check<jmol>
   <jmolCheckbox>
   <jmolCheckbox>
     <scriptWhenChecked>select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/pu/2pue_consurf.spt"</scriptWhenChecked>
     <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/pu/2pue_consurf.spt"</scriptWhenChecked>
     <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
     <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
     <text>to colour the structure by Evolutionary Conservation</text>
     <text>to colour the structure by Evolutionary Conservation</text>
   </jmolCheckbox>
   </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].
</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/main_output.php?pdb_ID=2pue ConSurf].
<div style="clear:both"></div>
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Guanine or hypoxanthine, physiological corepressors of the Escherichia coli purine repressor (PurR), promote formation of the ternary PurR-corepressor-operator DNA complex that functions to repress pur operon gene expression. Structure-based predictions on the importance of Arg190 in determining 6-oxopurine specificity and corepressor binding affinity were tested by mutagenesis, analysis of in vivo function, and in vitro corepressor binding measurements. Replacements of Arg190 with Ala or Gln resulted in functional repressors in which binding of guanine and hypoxanthine was retained but specificity was relaxed to permit binding of adenine. X-ray structures were determined for ternary complexes of mutant repressors with purines (adenine, guanine, hypoxanthine, and 6-methylpurine) and operator DNA. These structures indicate that R190A binds guanine, hypoxanthine, and adenine with nearly equal, albeit reduced, affinity in large part because of a newly made compensatory hydrogen bond between the rotated hydroxyl side chain of Ser124 and the exocyclic 6 positions of the purines. Through direct and water-mediated contacts, the R190Q protein binds adenine with a nearly 75-fold higher affinity than the wild type repressor while maintaining wild type affinity for guanine and hypoxanthine. The results establish at the atomic level the basis for the critical role of Arg190 in the recognition of the exocyclic 6 position of its purine corepressors and the successful redesign of corepressor specificity.
Structure-based redesign of corepressor specificity of the Escherichia coli purine repressor by substitution of residue 190.,Lu F, Schumacher MA, Arvidson DN, Haldimann A, Wanner BL, Zalkin H, Brennan RG Biochemistry. 1998 Jan 27;37(4):971-82. PMID:9454587<ref>PMID:9454587</ref>
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 2pue" style="background-color:#fffaf0;"></div>


==See Also==
==See Also==
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__TOC__
__TOC__
</StructureSection>
</StructureSection>
[[Category: Bacillus coli migula 1895]]
[[Category: Escherichia coli]]
[[Category: Arvidson, D N]]
[[Category: Large Structures]]
[[Category: Brennan, R G]]
[[Category: Arvidson DN]]
[[Category: Haldimann, A]]
[[Category: Brennan RG]]
[[Category: Lu, F]]
[[Category: Haldimann A]]
[[Category: Schumacher, M A]]
[[Category: Lu F]]
[[Category: Wanner, B L]]
[[Category: Schumacher MA]]
[[Category: Zalkin, H]]
[[Category: Wanner BL]]
[[Category: Dna-binding regulatory protein]]
[[Category: Zalkin H]]
[[Category: Extended corepressor specificity]]
[[Category: Transcription-dna complex]]

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