Alpha subunit of A. brasilense glutamate synthase

Experimental Data Snapshot

  • Resolution: 3.00 Å
  • R-Value Free: 0.287 
  • R-Value Work: 0.256 
  • R-Value Observed: 0.256 

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This is version 1.3 of the entry. See complete history


Cross-Talk and Ammonia Channeling between Active Centers in the Unexpected Domain Arrangement of Glutamate Synthase

Binda, C.Bossi, R.T.Wakatsuki, S.Arzt, S.Coda, A.Curti, B.Vanoni, M.A.Mattevi, A.

(2000) Structure 8: 1299

  • DOI: https://doi.org/10.1016/s0969-2126(00)00540-2
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    The complex iron-sulfur flavoprotein glutamate synthase catalyses the reductive synthesis of L-glutamate from 2-oxoglutarate and L-glutamine, a reaction in the plant and bacterial pathway for ammonia assimilation. The enzyme functions through three distinct active centers carrying out L-glutamine hydrolysis, conversion of 2-oxoglutarate into L-glutamate, and electron uptake from an electron donor. The 3.0 A crystal structure of the dimeric 324 kDa core protein of a bacterial glutamate synthase was solved by the MAD method, using the very weak anomalous signal of the two 3Fe-4S clusters present in the asymmetric unit. The 1,472 amino acids of the monomer fold into a four-domain architecture. The two catalytic domains have canonical Ntn-amidotransferase and FMN binding (beta/alpha)8 barrel folds, respectively. The other two domains have an unusual "cut (beta/alpha)8 barrel" topology and an unexpected novel beta-helix structure. Channeling of the ammonia intermediate is brought about by an internal tunnel of 31 A length, which runs from the site of L-glutamine hydrolysis to the site of L-glutamate synthesis. The outstanding property of glutamate synthase is the ability to coordinate the activity of its various functional sites to avoid wasteful consumption of L-glutamine. The structure reveals two polypeptide segments that connect the catalytic centers and embed the ammonia tunnel, thus being ideally suited to function in interdomain signaling. Depending on the enzyme redox and ligation states, these signal-transducing elements may affect the active site geometry and control ammonia diffusion through a gating mechanism.

  • Organizational Affiliation

    Dipartimento di Genetica e Microbiologia, Università degli Studi di Pavia, Italy.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B
1,479Azospirillum brasilenseMutation(s): 0 
Find proteins for Q05755 (Azospirillum brasilense)
Explore Q05755 
Go to UniProtKB:  Q05755
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ05755
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 3.00 Å
  • R-Value Free: 0.287 
  • R-Value Work: 0.256 
  • R-Value Observed: 0.256 
  • Space Group: P 31 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 233.612α = 90
b = 233.612β = 90
c = 305.089γ = 120
Software Package:
Software NamePurpose
MOSFLMdata reduction
CCP4data scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2001-11-01
    Type: Initial release
  • Version 1.1: 2011-05-08
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2024-05-08
    Changes: Data collection, Database references, Derived calculations, Other