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| - | [[Image:1yrw.gif|left|200px]] | + | {{Seed}} |
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| | {{STRUCTURE_1yrw| PDB=1yrw | SCENE= }} | | {{STRUCTURE_1yrw| PDB=1yrw | SCENE= }} |
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| - | '''Crystal Structure of E.coli ArnA Transformylase Domain'''
| + | ===Crystal Structure of E.coli ArnA Transformylase Domain=== |
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| - | ==Overview==
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| - | Gram-negative bacteria have evolved mechanisms to resist the bactericidal action of cationic antimicrobial peptides of the innate immune system and antibiotics such as polymyxin. The strategy involves the addition of the positively charged sugar 4-amino-4-deoxy-l-arabinose (Ara4N) to lipid A in their outer membrane. ArnA is a key enzyme in the Ara4N-lipid A modification pathway. It is a bifunctional enzyme catalyzing (1) the oxidative decarboxylation of UDP-glucuronic acid (UDP-GlcA) to the UDP-4' '-ketopentose [UDP-beta-(l-threo-pentapyranosyl-4' '-ulose] and (2) the N-10-formyltetrahydrofolate-dependent formylation of UDP-Ara4N. Here we demonstrate that the transformylase activity of the Escherichia coli ArnA is contained in its 300 N-terminal residues. We designate it the ArnA transformylase domain and describe its crystal structure solved to 1.7 A resolution. The enzyme adopts a bilobal structure with an N-terminal Rossmann fold domain containing the N-10-formyltetrahydrofolate binding site and a C-terminal subdomain resembling an OB fold. Sequence and structure conservation around the active site of ArnA transformylase and other N-10-formyltetrahydrofolate-utilizing enzymes suggests that the HxSLLPxxxG motif can be used to identify enzymes that belong to this family. Binding of an N-10-formyltetrahydrofolate analogue was modeled into the structure of ArnA based on its similarity with glycinamide ribonucleotide formyltransferase. We also propose a mechanism for the transformylation reaction catalyzed by ArnA involving residues N(102), H(104), and D(140). Supporting this hypothesis, point mutation of any of these residues abolishes activity.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_15807526}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 15807526 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_15807526}} |
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| | ==About this Structure== | | ==About this Structure== |
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| | [[Category: Ob-like fold]] | | [[Category: Ob-like fold]] |
| | [[Category: Rossmann fold]] | | [[Category: Rossmann fold]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 16:42:23 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun Jul 27 18:48:59 2008'' |
Revision as of 15:49, 27 July 2008
Template:STRUCTURE 1yrw
Crystal Structure of E.coli ArnA Transformylase Domain
Template:ABSTRACT PUBMED 15807526
About this Structure
1YRW is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Crystal structure and mechanism of the Escherichia coli ArnA (PmrI) transformylase domain. An enzyme for lipid A modification with 4-amino-4-deoxy-L-arabinose and polymyxin resistance., Gatzeva-Topalova PZ, May AP, Sousa MC, Biochemistry. 2005 Apr 12;44(14):5328-38. PMID:15807526
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