1ppx

<StructureSection load='1ppx' size='340' side='right'caption='[[1ppx]], [[NMR_Ensembles_of_Models | 20 NMR models]]' scene=''>

<table><tr><td colspan='2'>[[1ppx]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/"bacillus_coli"_migula_1895 "bacillus coli" migula 1895]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1PPX OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1PPX FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=8OG:8-OXO-2-DEOXY-GUANOSINE-5-MONOPHOSPHATE'>8OG</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene></td></tr>

<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat"><div style='overflow: auto; max-height: 3em;'>[[1mut|1mut]], [[1tum|1tum]]</div></td></tr>

<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">MUTT OR B0099 ([https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=562 "Bacillus coli" Migula 1895])</td></tr>

[[https://www.uniprot.org/uniprot/MUTT_ECOLI MUTT_ECOLI]] Involved in the GO system responsible for removing an oxidatively damaged form of guanine (7,8-dihydro-8-oxoguanine) from DNA and the nucleotide pool. 8-oxo-dGTP is inserted opposite dA and dC residues of template DNA with almost equal efficiency thus leading to A.T to G.C transversions. MutT specifically degrades 8-oxo-dGTP to the monophosphate.<ref>PMID:1309939</ref> <ref>PMID:15850400</ref>

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== Publication Abstract from PubMed ==

To learn the structural basis for the unusually tight binding of 8-oxo-nucleotides to the MutT pyrophosphohydrolase of Escherichia coli (129 residues), the solution structure of the MutT-Mg(2+)-8-oxo-dGMP product complex (K(D) = 52 nM) was determined by standard 3-D heteronuclear NMR methods. Using 1746 NOEs (13.5 NOEs/residue) and 186 phi and psi values derived from backbone (15)N, Calpha, Halpha, and Cbeta chemical shifts, 20 converged structures were computed with NOE violations &lt;or=0.25 A and total energies &lt;or=450 kcal/mol. The pairwise root-mean-square deviations (RMSD) of backbone N, Calpha, and C' atoms for the secondary structured regions and for all residues of the 20 structures are 0.65 and 0.98 A, respectively, indicating a well-defined structure. Further refinement using residual dipolar coupling from 53 backbone N-H vectors slightly improved the RMSD values to 0.49 and 0.84 A, respectively. The secondary structures, which consisted of two alpha-helices and a five-stranded mixed beta-sheet, were indistinguishable from those of free MutT and of MutT in the quaternary MutT-Mg(2+)-(H(2)O)-AMPCPP-Mg(2+) complex. Comparisons of these three tertiary structures showed a narrowing of the hydrophobic nucleotide-binding cleft in the 8-oxo-dGMP complex resulting from a 2.5-4.5 A movement of helix I and a 1.5 A movement of helix II and loop 4 toward the cleft. The binding of 8-oxo-dGMP to MutT-Mg(2+) buries 71-78% of the surface area of the nucleotide. The 10(3.7)-fold weaker binding substrate analogue Mg(2+)-AMPCPP induced much smaller changes in tertiary structure, and MutT buried only 57% of the surface of the AMP moiety of AMPCPP. Formation of the MutT-Mg(2+)-8-oxo-dGMP complex slowed the backbone NH exchange rates of 45 residues of the enzyme by factors of 10(1)-10(6) as compared with the MutT-Mg(2+) and the MutT-Mg(2+)-dGMP complexes, suggesting a more compact structure when 8-oxo-dGMP is bound. The 10(4.6)-fold weaker binding of dGMP to MutT-Mg(2+) (K(D) = 1.8 mM) slowed the backbone exchange rates of only 20 residues and by smaller factors of approximately 10. Hence, the high affinity of MutT-Mg(2+) for 8-oxo-dGMP likely results from widespread ligand-induced conformation changes that narrow the nucleotide binding site and lower the overall free energy of the enzyme-product complex. Specific hydrogen bonding of the purine ring of 8-oxo-dGMP by the side chains of Asn-119 and Arg-78 may also contribute.

Solution structure and NH exchange studies of the MutT pyrophosphohydrolase complexed with Mg(2+) and 8-oxo-dGMP, a tightly bound product.,Massiah MA, Saraswat V, Azurmendi HF, Mildvan AS Biochemistry. 2003 Sep 2;42(34):10140-54. PMID:12939141<ref>PMID:12939141</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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<div class="pdbe-citations 1ppx" style="background-color:#fffaf0;"></div>

[[Category: Bacillus coli migula 1895]]

[[Category: Azurmendi, H F]]

[[Category: Massiah, M A]]

[[Category: Mildvan, A S]]

[[Category: Saraswat, V]]

[[Category: Nucleoside triphosphate pyrophosphohydrolase]]