1me8

<StructureSection load='1me8' size='340' side='right' caption='[[1me8]], [[Resolution|resolution]] 1.90&Aring;' scene=''>

<table><tr><td colspan='2'>[[1me8]] is a 1 chain structure. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1ME8 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1ME8 FirstGlance]. <br>

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=K:POTASSIUM+ION'>K</scene>, <scene name='pdbligand=NA:SODIUM+ION'>NA</scene>, <scene name='pdbligand=RVP:RIBAVIRIN+MONOPHOSPHATE'>RVP</scene></td></tr>

<tr id='NonStdRes'><td class="sblockLbl"><b>[[Non-Standard_Residue|NonStd Res:]]</b></td><td class="sblockDat"><scene name='pdbligand=CSO:S-HYDROXYCYSTEINE'>CSO</scene></td></tr>

<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[1ak5|1ak5]], [[1me7|1me7]], [[1me9|1me9]], [[1meh|1meh]], [[1mei|1mei]], [[1mew|1mew]]</td></tr>

<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/IMP_dehydrogenase IMP dehydrogenase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=1.1.1.205 1.1.1.205] </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=1me8 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1me8 OCA], [http://pdbe.org/1me8 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1me8 RCSB], [http://www.ebi.ac.uk/pdbsum/1me8 PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=1me8 ProSAT]</span></td></tr>

[[http://www.uniprot.org/uniprot/IMDH_TRIFO IMDH_TRIFO]] Catalyzes the conversion of inosine 5'-phosphate (IMP) to xanthosine 5'-phosphate (XMP), the first committed and rate-limiting step in the de novo synthesis of guanine nucleotides, and therefore plays an important role in the regulation of cell growth. Could also have a single-stranded nucleic acid-binding activity and could play a role in RNA and/or DNA metabolism.<ref>PMID:10029522</ref>

<div style="background-color:#fffaf0;">

== Publication Abstract from PubMed ==

Inosine monophosphate dehydrogenase (IMPDH) catalyzes the rate-limiting step in GMP biosynthesis. The resulting intracellular pool of guanine nucleotides is of great importance to all cells for use in DNA and RNA synthesis, metabolism, and signal transduction. The enzyme binds IMP and the cofactor NAD(+) in random order, IMP is converted to XMP, NAD(+) is reduced to NADH, and finally, NADH and then XMP are released sequentially. XMP is subsequently converted into GMP by GMP synthetase. Drugs that decrease GMP synthesis by inhibiting IMPDH have been shown to have antiproliferative as well as antiviral activity. Several drugs are in use that target the substrate- or cofactor-binding site; however, due to differences between the mammalian and microbial isoforms, most drugs are far less effective against the microbial form of the enzyme than the mammalian form. The high resolution crystal structures of the protozoan parasite Tritrichomonas foetus IMPDH complexed with the inhibitor ribavirin monophosphate as well as monophosphate together with a second inhibitor, mycophenolic acid, are presented here. These structures reveal an active site cation identified previously only in the Chinese hamster IMPDH structure with covalently bound IMP. This cation was not found previously in apo IMPDH, IMPDH in complex with XMP, or covalently bound inhibitor, indicating that the cation-binding site may be catalysis-dependent. A comparison of T. foetus IMPDH with the Chinese hamster and Streptococcus pyogenes structures reveals differences in the active site loop architecture, which contributes to differences in cation binding during the catalytic sequence and the kinetic rates between bacterial, protozoan, and mammalian enzymes. Exploitation of these differences may lead to novel inhibitors, which favor the microbial form of the enzyme.

Crystal structure of Tritrichomonas foetus inosine monophosphate dehydrogenase in complex with the inhibitor ribavirin monophosphate reveals a catalysis-dependent ion-binding site.,Prosise GL, Wu JZ, Luecke H J Biol Chem. 2002 Dec 27;277(52):50654-9. Epub 2002 Sep 13. PMID:12235158<ref>PMID:12235158</ref>

 

[[Category: IMP dehydrogenase]]

[[Category: Luecke, H]]

[[Category: Prosise, G L]]

[[Category: Wu, J]]

[[Category: Alpha beta barrel]]

[[Category: Oxidoreductase]]