2bll: Difference between revisions

Revision as of 17:39, 21 February 2008

APO-STRUCTURE OF THE C-TERMINAL DECARBOXYLASE DOMAIN OF ARNA

OverviewOverview

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 StructureAbout this Structure

2BLL is a Single protein structure of sequence from Escherichia coli. Active as UDP-glucuronate decarboxylase, with EC number 4.1.1.35 Full crystallographic information is available from OCA.

ReferenceReference

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

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-[[Image:2bll.gif|left|200px]]<br /><applet load="2bll" size="450" color="white" frame="true" align="right" spinBox="true"
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 caption="2bll, resolution 2.30&Aring;" />
 '''APO-STRUCTURE OF THE C-TERMINAL DECARBOXYLASE DOMAIN OF ARNA'''<br />
 ==Overview==
-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.
+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==
-BLL is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Active as [http://en.wikipedia.org/wiki/UDP-glucuronate_decarboxylase UDP-glucuronate decarboxylase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.1.1.35 4.1.1.35] Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=2BLL OCA].
+BLL is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Active as [http://en.wikipedia.org/wiki/UDP-glucuronate_decarboxylase UDP-glucuronate decarboxylase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=4.1.1.35 4.1.1.35] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2BLL OCA].
 ==Reference==
@@ Line 14: / Line 14: @@
 [[Category: Single protein]]
 [[Category: UDP-glucuronate decarboxylase]]
-[[Category: Breazeale, S.D.]]
+[[Category: Breazeale, S D.]]
-[[Category: Naismith, J.H.]]
+[[Category: Naismith, J H.]]
-[[Category: Raetz, C.R.H.]]
+[[Category: Raetz, C R.H.]]
-[[Category: Williams, G.J.]]
+[[Category: Williams, G J.]]
 [[Category: decarboxylase]]
 [[Category: l-ara4n biosynthesis]]
@@ Line 24: / Line 24: @@
 [[Category: transferase]]
-''Page seeded by [http://ispc.weizmann.ac.il/oca OCA ] on Wed Nov 21 08:49:36 2007''
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