3UZO

Crystal Structures of Branched-Chain Aminotransferase from Deinococcus radiodurans Complexes with alpha-Ketoisocaproate and L-Glutamate Suggest Its Radio-Resistance for Catalysis


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 0.263 
  • R-Value Work: 0.221 
  • R-Value Observed: 0.221 

Starting Model: experimental
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Literature

Crystal Structures of Complexes of the Branched-Chain Aminotransferase from Deinococcus radiodurans with alpha-Ketoisocaproate and L-Glutamate Suggest the Radiation Resistance of This Enzyme for Catalysis

Chen, C.D.Lin, C.H.Chuankhayan, P.Huang, Y.C.Hsieh, Y.C.Huang, T.F.Guan, H.H.Liu, M.Y.Chang, W.C.Chen, C.J.

(2012) J Bacteriol 194: 6206-6216

  • DOI: https://doi.org/10.1128/JB.01659-12
  • Primary Citation of Related Structures:  
    3UYY, 3UZB, 3UZO

  • PubMed Abstract: 

    Branched-chain aminotransferases (BCAT), which utilize pyridoxal 5'-phosphate (PLP) as a cofactor, reversibly catalyze the transfer of the α-amino groups of three of the most hydrophobic branched-chain amino acids (BCAA), leucine, isoleucine, and valine, to α-ketoglutarate to form the respective branched-chain α-keto acids and glutamate. The BCAT from Deinococcus radiodurans (DrBCAT), an extremophile, was cloned and expressed in Escherichia coli for structure and functional studies. The crystal structures of the native DrBCAT with PLP and its complexes with L-glutamate and α-ketoisocaproate (KIC), respectively, have been determined. The DrBCAT monomer, comprising 358 amino acids, contains large and small domains connected with an interdomain loop. The cofactor PLP is located at the bottom of the active site pocket between two domains and near the dimer interface. The substrate (L-glutamate or KIC) is bound with key residues through interactions of the hydrogen bond and the salt bridge near PLP inside the active site pocket. Mutations of some interaction residues, such as Tyr71, Arg145, and Lys202, result in loss of the specific activity of the enzymes. In the interdomain loop, a dynamic loop (Gly173 to Gly179) clearly exhibits open and close conformations in structures of DrBCAT without and with substrates, respectively. DrBCAT shows the highest specific activity both in nature and under ionizing radiation, but with lower thermal stability above 60 °C, than either BCAT from Escherichia coli (eBCAT) or from Thermus thermophilus (HB8BCAT). The dimeric molecular packing and the distribution of cysteine residues at the active site and the molecular surface might explain the resistance to radiation but small thermal stability of DrBCAT.


  • Organizational Affiliation

    Life Science Group, Scientific Research Division, National Synchrotron Radiation Research Center, Hsinchu, Taiwan.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Branched-chain-amino-acid aminotransferase
A, B
358Deinococcus radioduransMutation(s): 0 
Gene Names: DR_1626
EC: 2.6.1.42
UniProt
Find proteins for Q9RTX5 (Deinococcus radiodurans (strain ATCC 13939 / DSM 20539 / JCM 16871 / CCUG 27074 / LMG 4051 / NBRC 15346 / NCIMB 9279 / VKM B-1422 / R1))
Explore Q9RTX5 
Go to UniProtKB:  Q9RTX5
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ9RTX5
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 0.263 
  • R-Value Work: 0.221 
  • R-Value Observed: 0.221 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 55.881α = 90
b = 75.98β = 105.98
c = 79.123γ = 90
Software Package:
Software NamePurpose
HKL-2000data collection
CNSrefinement
HKL-2000data reduction
HKL-2000data scaling
CNSphasing

Structure Validation

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Ligand Structure Quality Assessment 


Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2012-12-12
    Type: Initial release
  • Version 1.1: 2023-11-08
    Changes: Data collection, Database references, Derived calculations, Refinement description