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==PURINE REPRESSOR-HYPOXANTHINE-PALINDROMIC OPERATOR COMPLEX==
==PURINE REPRESSOR-HYPOXANTHINE-PALINDROMIC OPERATOR COMPLEX==
<StructureSection load='1qp4' size='340' side='right' caption='[[1qp4]], [[Resolution|resolution]] 3.00&Aring;' scene=''>
<StructureSection load='1qp4' size='340' side='right'caption='[[1qp4]], [[Resolution|resolution]] 3.00&Aring;' scene=''>
== Structural highlights ==
== Structural highlights ==
<table><tr><td colspan='2'>[[1qp4]] 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=1QP4 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1QP4 FirstGlance]. <br>
<table><tr><td colspan='2'>[[1qp4]] 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=1QP4 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1QP4 FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=HPA:HYPOXANTHINE'>HPA</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]] 3&#8491;</td></tr>
<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[1bdh|1bdh]], [[1qpz|1qpz]], [[1qp0|1qp0]], [[1qp7|1qp7]]</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=HPA:HYPOXANTHINE'>HPA</scene></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='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1qp4 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1qp4 OCA], [https://pdbe.org/1qp4 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1qp4 RCSB], [https://www.ebi.ac.uk/pdbsum/1qp4 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1qp4 ProSAT]</span></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=1qp4 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1qp4 OCA], [http://pdbe.org/1qp4 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1qp4 RCSB], [http://www.ebi.ac.uk/pdbsum/1qp4 PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=1qp4 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]]
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</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=1qp4 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=1qp4 ConSurf].
<div style="clear:both"></div>
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The interaction of the dimeric Escherichia coli purine repressor (PurR) with its cognate sequences leads to a 45 degrees to 50 degrees kink at a central CpG base step towards the major groove, as dyad-related leucine side-chains interdigitate between these bases from the minor groove. The resulting broadening of the minor groove increases the accessibility of the six central base-pairs towards minor groove interactions with residues from PurR. It has been shown that lysine 55 of PurR makes a direct contact with the adenine base (Ade8) directly 5' to the central CpG base-pair step in the high-affinity purF operator sequence. We have investigated the importance of this interaction in the specificity and affinity of wild-type PurR (WT) for its operators and we have studied a mutant of PurR in which Lys55 is replaced with alanine (K55A). Complexes of WT and K55A with duplex DNA containing pur operator sequences varied at position 8 were investigated crystallographically, and binding studies were performed using fluorescence anisotropy. The structures of the protein-DNA complexes reveal a relatively unperturbed global conformation regardless of the identity of the base-pair at position 8 or residue 55. In all structures the combination of higher resolution and a palindromic purF operator site allowed several new PurR.DNA interactions to be observed, including contacts by Thr15, Thr16 and His20. The side-chain of Lys55 makes productive, though varying, interactions with the adenine, thymine or cytosine base at position 8 that result in equilibrium dissociation constants of 2.6 nM, 10 nM and 35 nM, respectively. However, the bulk of the lysine side-chain apparently blocks high-affinity binding of operators with guanine at position 8 (Kd620 nM). Also, the high-affinity binding conformation appears blocked, as crystals of WT bound to DNA with guanine at position 8 could not be grown. In complexes containing K55A, the alanine side-chain is too far removed to engage in van der Waals interactions with the operator, and, with the loss of the general electrostatic interaction between the phosphate backbone and the ammonium group of lysine, K55A binds each operator weakly. However, the mutation leads to a swap of specificity of PurR for the base at position 8, with K55A exhibiting a twofold preference for guanine over adenine. In addition to defining the role of Lys55 in PurR minor groove binding, these studies provide structural insight into the minor groove binding specificities of other LacI/GalR family members that have either alanine (e.g. LacI, GalR, CcpA) or a basic residue (e.g. RafR, ScrR, RbtR) at the comparable position.
The role of lysine 55 in determining the specificity of the purine repressor for its operators through minor groove interactions.,Glasfeld A, Koehler AN, Schumacher MA, Brennan RG J Mol Biol. 1999 Aug 13;291(2):347-61. PMID:10438625<ref>PMID:10438625</ref>
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 1qp4" 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: Brennan, R G]]
[[Category: Large Structures]]
[[Category: Glasfeld, A]]
[[Category: Brennan RG]]
[[Category: Koehler, A N]]
[[Category: Glasfeld A]]
[[Category: Schumacher, M A]]
[[Category: Koehler AN]]
[[Category: Dna-binding]]
[[Category: Schumacher MA]]
[[Category: Purine biosynthesis]]
[[Category: Repressor]]
[[Category: Transcription regulation]]
[[Category: Transcription-dna complex]]

Latest revision as of 11:15, 14 February 2024

PURINE REPRESSOR-HYPOXANTHINE-PALINDROMIC OPERATOR COMPLEXPURINE REPRESSOR-HYPOXANTHINE-PALINDROMIC OPERATOR COMPLEX

Structural highlights

1qp4 is a 2 chain structure with sequence from Escherichia coli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:X-ray diffraction, Resolution 3Å
Ligands:
Resources:FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

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.[1] [2] [3] [4]

Evolutionary Conservation

Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf.

See Also

References

  1. ↑ Meng LM, Kilstrup M, Nygaard P. Autoregulation of PurR repressor synthesis and involvement of purR in the regulation of purB, purC, purL, purMN and guaBA expression in Escherichia coli. Eur J Biochem. 1990 Jan 26;187(2):373-9. PMID:2404765
  2. ↑ Rolfes RJ, Zalkin H. Purification of the Escherichia coli purine regulon repressor and identification of corepressors. J Bacteriol. 1990 Oct;172(10):5637-42. PMID:2211500
  3. ↑ Choi KY, Zalkin H. Structural characterization and corepressor binding of the Escherichia coli purine repressor. J Bacteriol. 1992 Oct;174(19):6207-14. PMID:1400170
  4. ↑ Devroede N, Thia-Toong TL, Gigot D, Maes D, Charlier D. Purine and pyrimidine-specific repression of the Escherichia coli carAB operon are functionally and structurally coupled. J Mol Biol. 2004 Feb 6;336(1):25-42. PMID:14741201

1qp4, resolution 3.00Å

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