1YRW

Crystal Structure of E.coli ArnA Transformylase Domain


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.7 Å
  • R-Value Free: 0.225 
  • R-Value Work: 0.198 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

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, P.Z.May, A.P.Sousa, M.C.

(2005) Biochemistry 44: 5328-5338

  • DOI: 10.1021/bi047384g

  • PubMed Abstract: 
  • 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-am ...

    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.


    Organizational Affiliation

    Department of Chemistry and Biochemistry, University of Colorado at Boulder, 80309, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
protein ArnA
A
302Escherichia coli (strain K12)Gene Names: arnA (pmrI, yfbG)
EC: 2.1.2.13, 1.1.1.305
Find proteins for P77398 (Escherichia coli (strain K12))
Go to UniProtKB:  P77398
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.7 Å
  • R-Value Free: 0.225 
  • R-Value Work: 0.198 
  • Space Group: C 2 2 21
Unit Cell:
Length (Å)Angle (°)
a = 59.103α = 90.00
b = 113.253β = 90.00
c = 124.946γ = 90.00
Software Package:
Software NamePurpose
CNSrefinement
SCALEPACKdata scaling
AMoREphasing
DENZOdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2005-04-12
    Type: Initial release
  • Version 1.1: 2008-04-30
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance