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[[Image:2bln.gif|left|200px]]<br /><applet load="2bln" size="450" color="white" frame="true" align="right" spinBox="true"
caption="2bln, resolution 1.20&Aring;" />
'''N-TERMINAL FORMYLTRANSFERASE DOMAIN OF ARNA IN COMPLEX WITH N-5-FORMYLTETRAHYDROFOLATE AND UMP'''<br />


==Overview==
==N-terminal formyltransferase domain of ArnA in complex with N-5- formyltetrahydrofolate and UMP==
Modification of the lipid A moiety of lipopolysaccharide by the addition, of the sugar 4-amino-4-deoxy-L-arabinose (L-Ara4N) is a strategy adopted, by pathogenic Gram-negative bacteria to evade cationic antimicrobial, peptides produced by the innate immune system. L-Ara4N biosynthesis is, therefore a potential anti-infective target, because inhibiting its, synthesis would render certain pathogens more sensitive to the immune, system. The bifunctional enzyme ArnA, which is required for L-Ara4N, biosynthesis, catalyzes the NAD(+)-dependent oxidative decarboxylation of, UDP-glucuronic acid to generate a UDP-4'-keto-pentose sugar and also, catalyzes transfer of a formyl group from N-10-formyltetrahydrofolate to, the 4'-amine of UDP-L-Ara4N. We now report the crystal structure of the, N-terminal formyltransferase domain in a complex with uridine, monophosphate and N-5-formyltetrahydrofolate. Using this structure, we, identify the active site of formyltransfer in ArnA, including the key, catalytic residues Asn(102), His(104), and Asp(140). Additionally, we have, shown that residues Ser(433) and Glu(434) of the decarboxylase domain are, required for the oxidative decarboxylation of UDP-GlcUA. An E434Q mutant, is inactive, suggesting that chemical rather than steric properties of, this residue are crucial in the decarboxylation reaction. Our data suggest, that the decarboxylase domain catalyzes both hydride abstraction, (oxidation) from the C-4' position and the subsequent decarboxylation.
<StructureSection load='2bln' size='340' side='right'caption='[[2bln]], [[Resolution|resolution]] 1.20&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2bln]] 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=2BLN OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2BLN 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]] 1.2&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ACT:ACETATE+ION'>ACT</scene>, <scene name='pdbligand=FON:N-{[4-({[(6R)-2-AMINO-5-FORMYL-4-OXO-1,4,5,6,7,8-HEXAHYDROPTERIDIN-6-YL]METHYL}AMINO)PHENYL]CARBONYL}-L-GLUTAMIC+ACID'>FON</scene>, <scene name='pdbligand=U5P:URIDINE-5-MONOPHOSPHATE'>U5P</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=2bln FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2bln OCA], [https://pdbe.org/2bln PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2bln RCSB], [https://www.ebi.ac.uk/pdbsum/2bln PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2bln ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/ARNA_ECOLI ARNA_ECOLI] Bifunctional enzyme that catalyzes the oxidative decarboxylation of UDP-glucuronic acid (UDP-GlcUA) to UDP-4-keto-arabinose (UDP-Ara4O) and the addition of a formyl group to UDP-4-amino-4-deoxy-L-arabinose (UDP-L-Ara4N) to form UDP-L-4-formamido-arabinose (UDP-L-Ara4FN). The modified arabinose is attached to lipid A and is required for resistance to polymyxin and cationic antimicrobial peptides.<ref>PMID:11706007</ref> <ref>PMID:15695810</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/bl/2bln_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=2bln ConSurf].
<div style="clear:both"></div>
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Modification of the lipid A moiety of lipopolysaccharide by the addition of the sugar 4-amino-4-deoxy-L-arabinose (L-Ara4N) is a strategy adopted by pathogenic Gram-negative bacteria to evade cationic antimicrobial peptides produced by the innate immune system. L-Ara4N biosynthesis is therefore a potential anti-infective target, because inhibiting its synthesis would render certain pathogens more sensitive to the immune system. The bifunctional enzyme ArnA, which is required for L-Ara4N biosynthesis, catalyzes the NAD(+)-dependent oxidative decarboxylation of UDP-glucuronic acid to generate a UDP-4'-keto-pentose sugar and also catalyzes transfer of a formyl group from N-10-formyltetrahydrofolate to the 4'-amine of UDP-L-Ara4N. We now report the crystal structure of the N-terminal formyltransferase domain in a complex with uridine monophosphate and N-5-formyltetrahydrofolate. Using this structure, we identify the active site of formyltransfer in ArnA, including the key catalytic residues Asn(102), His(104), and Asp(140). Additionally, we have shown that residues Ser(433) and Glu(434) of the decarboxylase domain are required for the oxidative decarboxylation of UDP-GlcUA. An E434Q mutant is inactive, suggesting that chemical rather than steric properties of this residue are crucial in the decarboxylation reaction. Our data suggest that the decarboxylase domain catalyzes both hydride abstraction (oxidation) from the C-4' position and the subsequent decarboxylation.


==About this Structure==
Structure and function of both domains of ArnA, a dual function decarboxylase and a formyltransferase, involved in 4-amino-4-deoxy-L-arabinose biosynthesis.,Williams GJ, Breazeale SD, Raetz CR, Naismith JH J Biol Chem. 2005 Jun 17;280(24):23000-8. Epub 2005 Apr 4. PMID:15809294<ref>PMID:15809294</ref>
2BLN is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli] with ACT, FON and U5P as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Guanidinoacetate_N-methyltransferase Guanidinoacetate N-methyltransferase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=2.1.1.2 2.1.1.2] Known structural/functional Site: <scene name='pdbsite=AC1:Act Binding Site For Chain B'>AC1</scene>. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=2BLN OCA].


==Reference==
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
Structure and function of both domains of ArnA, a dual function decarboxylase and a formyltransferase, involved in 4-amino-4-deoxy-L-arabinose biosynthesis., Williams GJ, Breazeale SD, Raetz CR, Naismith JH, J Biol Chem. 2005 Jun 17;280(24):23000-8. Epub 2005 Apr 4. PMID:[http://ispc.weizmann.ac.il//pmbin/getpm?pmid=15809294 15809294]
</div>
<div class="pdbe-citations 2bln" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia coli]]
[[Category: Escherichia coli]]
[[Category: Guanidinoacetate N-methyltransferase]]
[[Category: Large Structures]]
[[Category: Single protein]]
[[Category: Breazeale SD]]
[[Category: Breazeale, S.D.]]
[[Category: Naismith JH]]
[[Category: Naismith, J.H.]]
[[Category: Raetz CRH]]
[[Category: Raetz, C.R.H.]]
[[Category: Williams GJ]]
[[Category: Williams, G.J.]]
[[Category: ACT]]
[[Category: FON]]
[[Category: U5P]]
[[Category: formyltransferase]]
[[Category: l-ara4n biosynthesis]]
[[Category: methyltransferase]]
[[Category: transferase]]
 
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