2BTY

Acetylglutamate kinase from Thermotoga maritima complexed with its inhibitor arginine


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.75 Å
  • R-Value Free: 0.273 
  • R-Value Work: 0.242 
  • R-Value Observed: 0.242 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Structural Bases of Feed-Back Control of Arginine Biosynthesis, Revealed by the Structure of Two Hexameric N-Acetylglutamate Kinases, from Thermotoga Maritima and Pseudomonas Aeruginosa

Ramon-Maiques, S.Fernandez-Murga, M.L.Gil-Ortiz, F.Vagin, A.Fita, I.Rubio, V.

(2006) J Mol Biol 356: 695

  • DOI: 10.1016/j.jmb.2005.11.079
  • Primary Citation of Related Structures:  
    2BTY, 2BUF

  • PubMed Abstract: 
  • N-Acetylglutamate kinase (NAGK) catalyses the second step in the route of arginine biosynthesis. In many organisms this enzyme is inhibited by the final product of the route, arginine, and thus plays a central regulatory role. In addition, in photosy ...

    N-Acetylglutamate kinase (NAGK) catalyses the second step in the route of arginine biosynthesis. In many organisms this enzyme is inhibited by the final product of the route, arginine, and thus plays a central regulatory role. In addition, in photosynthetic organisms NAGK is the target of the nitrogen-signalling protein PII. The 3-D structure of homodimeric, arginine-insensitive, Escherichia coli NAGK, clarified substrate binding and catalysis but shed no light on arginine inhibition of NAGK. We now shed light on arginine inhibition by determining the crystal structures, at 2.75 A and 2.95 A resolution, of arginine-complexed Thermotoga maritima and arginine-free Pseudomonas aeruginosa NAGKs, respectively. Both enzymes are highly similar ring-like hexamers having a central orifice of approximately 30 A diameter. They are formed by linking three E.coli NAGK-like homodimers through the interlacing of an N-terminal mobile kinked alpha-helix, which is absent from E.coli NAGK. Arginine is bound in each subunit of T.maritima NAGK, flanking the interdimeric junction, in a site formed between the N helix and the C lobe of the subunit. This site is also present, in variable conformations, in P.aeruginosa NAGK, but is missing from E.coli NAGK. Arginine, by gluing the C lobe of each subunit to the inter-dimeric junction, may stabilize an enlarged active centre conformation, hampering catalysis. Acetylglutamate counters arginine inhibition by promoting active centre closure. The hexameric architecture justifies the observed sigmoidal arginine inhibition kinetics with a high Hill coefficient (N approximately 4), and appears essential for arginine inhibition and for NAGK-PII complex formation, since this complex may involve binding of NAGK and PII with their 3-fold axes aligned. The NAGK structures allow identification of diagnostic sequence signatures for arginine inhibition. These signatures are found also in the homologous arginine-inhibited enzyme NAG synthase. The findings on NAGK shed light on the structure, function and arginine inhibition of this synthase, for which a hexameric model is constructed.


    Organizational Affiliation

    Instituto de Biomedicina de Valencia (CSIC), Jaume Roig 11, Valencia 46010, Spain.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
ACETYLGLUTAMATE KINASEABC282Thermotoga maritimaMutation(s): 0 
EC: 2.7.2.8
Find proteins for Q9X2A4 (Thermotoga maritima (strain ATCC 43589 / MSB8 / DSM 3109 / JCM 10099))
Explore Q9X2A4 
Go to UniProtKB:  Q9X2A4
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
NLG
Query on NLG

Download CCD File 
A, B, C
N-ACETYL-L-GLUTAMATE
C7 H11 N O5
RFMMMVDNIPUKGG-YFKPBYRVSA-N
 Ligand Interaction
ARG
Query on ARG

Download CCD File 
A, B, C
ARGININE
C6 H15 N4 O2
ODKSFYDXXFIFQN-BYPYZUCNSA-O
 Ligand Interaction
K
Query on K

Download CCD File 
A
POTASSIUM ION
K
NPYPAHLBTDXSSS-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.75 Å
  • R-Value Free: 0.273 
  • R-Value Work: 0.242 
  • R-Value Observed: 0.242 
  • Space Group: C 2 2 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 94.998α = 90
b = 207.709β = 90
c = 117.996γ = 90
Software Package:
Software NamePurpose
CNSrefinement
MOSFLMdata reduction
SCALAdata scaling
MOLREPphasing

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2005-12-13
    Type: Initial release
  • Version 1.1: 2011-05-08
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance