View source for 1tmj


==Crystal structure of E.coli apo-HPPK(W89A) at 1.45 Angstrom resolution==
<StructureSection load='1tmj' size='340' side='right'caption='[[1tmj]], [[Resolution|resolution]] 1.45&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1tmj]] is a 1 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=1TMJ OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1TMJ FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 1.45&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene></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=1tmj FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1tmj OCA], [https://pdbe.org/1tmj PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1tmj RCSB], [https://www.ebi.ac.uk/pdbsum/1tmj PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1tmj ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/HPPK_ECOLI HPPK_ECOLI] 
== 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/tm/1tmj_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/main_output.php?pdb_ID=1tmj ConSurf].
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== Publication Abstract from PubMed ==
Deletion mutagenesis, biochemical, and X-ray crystallographic studies have shown that loop 3 of Escherichia coli 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase (HPPK) is required for the assembly of the active center, plays an important role in the stabilization of the ternary complex of HPPK with MgATP and 6-hydroxymethyl-7,8-dihydropterin (HP), and is essential for catalysis. Whether the critical functional importance of loop 3 is due to the interactions between residues R84 and W89 and the two substrates has been addressed by site-directed mutagenesis, biochemical, and X-ray crystallographic studies. Substitution of R84 with alanine causes little changes in the dissociation constants and kinetic constants of the HPPK-catalyzed reaction, indicating that R84 is not important for either substrate binding or catalysis. Substitution of W89 with alanine increases the K(d) for the binding of MgATP by a factor of 3, whereas the K(d) for HP increases by a factor of 6, which is due to the increase in the dissociation rate constant. The W89A mutation decreases the rate constant for the chemical step of the forward reaction by a factor of 15 and the rate constant for the chemical step of the reverse reaction by a factor of 25. The biochemical results of the W89A mutation indicate that W89 contributes somewhat to the binding of HP and more significantly to the chemical step. The crystal structures of W89A show that W89A has different conformations in loops 2 and 3, but the critical catalytic residues are positioned for catalysis. When these results are taken together, they suggest that the critical functional importance of loop 3 is not due to the interactions of the R84 guanidinium group or the W89 indole ring with the substrates.

Is the critical role of loop 3 of Escherichia coli 6-hydroxymethyl-7,8-dihydropterin pyrophosphokinase in catalysis due to loop-3 residues arginine-84 and tryptophan-89? Site-directed mutagenesis, biochemical, and crystallographic studies.,Li Y, Blaszczyk J, Wu Y, Shi G, Ji X, Yan H Biochemistry. 2005 Jun 21;44(24):8590-9. PMID:15952765<ref>PMID:15952765</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 1tmj" style="background-color:#fffaf0;"></div>

==See Also==
*[[HPPK 3D structures|HPPK 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia coli]]
[[Category: Large Structures]]
[[Category: Blaszczyk J]]
[[Category: Ji X]]