View source for 2xbn


==Inhibition of the PLP-dependent enzyme serine palmitoyltransferase by cycloserine: evidence for a novel decarboxylative mechanism of inactivation==
<StructureSection load='2xbn' size='340' side='right'caption='[[2xbn]], [[Resolution|resolution]] 1.40&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2xbn]] is a 1 chain structure with sequence from [https://en.wikipedia.org/wiki/Sphingomonas_paucimobilis Sphingomonas paucimobilis]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2XBN OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2XBN 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]] 1.4&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=MG:MAGNESIUM+ION'>MG</scene>, <scene name='pdbligand=PMP:4-DEOXY-4-AMINOPYRIDOXAL-5-PHOSPHATE'>PMP</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=2xbn FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2xbn OCA], [https://pdbe.org/2xbn PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2xbn RCSB], [https://www.ebi.ac.uk/pdbsum/2xbn PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2xbn ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/SPT_SPHPI SPT_SPHPI] Catalyzes the condensation of L-serine with palmitoyl-CoA (hexadecanoyl-CoA) to produce 3-oxosphinganine (PubMed:11279212, PubMed:17557831, PubMed:17559874, PubMed:19376777). Exhibits a broad substrate specificity concerning the chain length and the degree of unsaturation of acyl-CoA (PubMed:11279212, PubMed:19376777).<ref>PMID:11279212</ref> <ref>PMID:17557831</ref> <ref>PMID:17559874</ref> <ref>PMID:19376777</ref> 
== 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/xb/2xbn_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=2xbn ConSurf].
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Cycloserine (CS, 4-amino-3-isoxazolidone) is a cyclic amino acid mimic that is known to inhibit many essential pyridoxal 5'-phosphate (PLP)-dependent enzymes. Two CS enantiomers are known; d-cycloserine (DCS, also known as Seromycin) is a natural product that is used to treat resistant Mycobacterium tuberculosis infections as well as neurological disorders since it is a potent NMDA receptor agonist, and l-cycloserine (LCS) is a synthetic enantiomer whose usefulness as a drug has been hampered by its inherent toxicity arising through inhibition of sphingolipid metabolism. Previous studies on various PLP-dependent enzymes revealed a common mechanism of inhibition by both enantiomers of CS; the PLP cofactor is disabled by forming a stable 3-hydroxyisoxazole/pyridoxamine 5'-phosphate (PMP) adduct at the active site where the cycloserine ring remains intact. Here we describe a novel mechanism of CS inactivation of the PLP-dependent enzyme serine palmitoyltransferase (SPT) from Sphingomonas paucimobilis. SPT catalyses the condensation of l-serine and palmitoyl-CoA, the first step in the de novo sphingolipid biosynthetic pathway. We have used a range of kinetic, spectroscopic and structural techniques to postulate that both LCS and DCS inactivate SPT by transamination to form a free pyridoxamine 5'-phosphate (PMP) and beta-aminooxyacetaldehyde that remain bound at the active site. We suggest this occurs by ring opening of the cycloserine ring followed by decarboxylation. Enzyme kinetics show that inhibition is reversed by incubation with excess PLP and that LCS is a more effective SPT inhibitor than DCS. UV-visible spectroscopic data, combined with site-directed mutagenesis, suggest that a mobile Arg(378) residue is involved in cycloserine inactivation of SPT.

Inhibition of the PLP-dependent enzyme serine palmitoyltransferase by cycloserine: evidence for a novel decarboxylative mechanism of inactivation.,Lowther J, Yard BA, Johnson KA, Carter LG, Bhat VT, Raman MC, Clarke DJ, Ramakers B, McMahon SA, Naismith JH, Campopiano DJ Mol Biosyst. 2010 May 5. PMID:20445930<ref>PMID:20445930</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 2xbn" style="background-color:#fffaf0;"></div>

==See Also==
*[[Serine palmitoyltransferase 3D structures|Serine palmitoyltransferase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Large Structures]]
[[Category: Sphingomonas paucimobilis]]
[[Category: Bhat VT]]
[[Category: Campopiano DJ]]
[[Category: Carter LG]]
[[Category: Clarke DJ]]
[[Category: Johnson KA]]
[[Category: Lowther J]]
[[Category: McMahon SA]]
[[Category: Naismith JH]]
[[Category: Ramakers B]]
[[Category: Raman MCC]]
[[Category: Yard BA]]