2HGW

Crystal structure of Cys318Ala mutant of human mitochondrial branched chain aminotransferase

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.98 Å
  • R-Value Free: 0.254 
  • R-Value Work: 0.227 
  • R-Value Observed: 0.227 

wwPDB Validation   3D Report Full Report


This is version 1.3 of the entry. See complete history. 


Literature

Human Mitochondrial Branched Chain Aminotransferase Isozyme: STRUCTURAL ROLE OF THE CXXC CENTER IN CATALYSIS.

Yennawar, N.H., Islam, M.M., Conway, M., Wallin, R., Hutson, S.M.

(2006) J Biol Chem 281: 39660-39671

  • DOI: 10.1074/jbc.M607552200
  • Primary Citation of Related Structures:  
    2HDK, 2HG8, 2HHF, 2HGX, 2HGW

  • PubMed Abstract: 

    • Mammalian branched chain aminotransferases (BCATs) have a unique CXXC center. Kinetic and structural studies of three CXXC center mutants (C315A, C318A, and C315A/C318A) of human mitochondrial (hBCATm) isozyme and the oxidized hBCATm enzyme (hBCATm-Ox) h ...

    Mammalian branched chain aminotransferases (BCATs) have a unique CXXC center. Kinetic and structural studies of three CXXC center mutants (C315A, C318A, and C315A/C318A) of human mitochondrial (hBCATm) isozyme and the oxidized hBCATm enzyme (hBCATm-Ox) have been used to elucidate the role of this center in hBCATm catalysis. X-ray crystallography revealed that the CXXC motif, through its network of hydrogen bonds, plays a crucial role in orienting the substrate optimally for catalysis. In all structures, there were changes in the structure of the beta-turn preceding the CXXC motif when compared with wild type protein. The N-terminal loop between residues 15 and 32 is flexible in the oxidized and mutant enzymes, the disorder greater in the oxidized protein. Disordering of the N-terminal loop disrupts the integrity of the side chain binding pocket, particularly for the branched chain side chain, less so for the dicarboxylate substrate side chain. The kinetic studies of the mutant and oxidized enzymes support the structural analysis. The kinetic results showed that the predominant effect of oxidation was on the second half-reaction rather than the first half-reaction. The oxidized enzyme was completely inactive, whereas the mutants showed limited activity. Model building of the second half-reaction substrate alpha-ketoisocaproate in the pyridoxamine 5'-phosphate-hBCATm structure suggests that disruption of the CXXC center results in altered substrate orientation and deprotonation of the amino group of pyridoxamine 5'-phosphate, which inhibits catalysis.

    Organizational Affiliation: 

    Departments of Biochemistry and Internal Medicine, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.



Macromolecules
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(by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Branched-chain-amino-acid aminotransferase, mitochondrial A, B365Homo sapiensMutation(s): 1 
Gene Names: BCAT2, BCATM, ECA40, BCT2
EC: 2.6.1.42
Find proteins for O15382 (Homo sapiens)
Explore O15382 
Go to UniProtKB:  O15382
NIH Common Fund Data Resources
PHAROS:  O15382
GTEx:  ENSG00000105552
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Ligands 5 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
PLP
Query on PLP
Download Ideal Coordinates CCD File 
A, B
PYRIDOXAL-5'-PHOSPHATE
C8 H10 N O6 P
NGVDGCNFYWLIFO-UHFFFAOYSA-N		 Ligand Interaction
EPE
Query on EPE
Download Ideal Coordinates CCD File 
A
4-(2-HYDROXYETHYL)-1-PIPERAZINE ETHANESULFONIC ACID
C8 H18 N2 O4 S
JKMHFZQWWAIEOD-UHFFFAOYSA-N		 Ligand Interaction
SO4
Query on SO4
Download Ideal Coordinates CCD File 
B
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L		 Ligand Interaction
GOL
Query on GOL
Download Ideal Coordinates CCD File 
A
GLYCEROL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N		 Ligand Interaction
ACY
Query on ACY
Download Ideal Coordinates CCD File 
A, B
ACETIC ACID
C2 H4 O2
QTBSBXVTEAMEQO-UHFFFAOYSA-N		 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.98 Å
  • R-Value Free: 0.254 
  • R-Value Work: 0.227 
  • R-Value Observed: 0.227 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 69.668α = 90
b = 105.585β = 90
c = 106.599γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
CNSrefinement
PDB_EXTRACTdata extraction
AMoREphasing

Structure Validation

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View more in-depth experimental data

Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2006-10-24
    Type: Initial release
  • Version 1.1: 2008-05-01
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Non-polymer description, Version format compliance
  • Version 1.3: 2017-10-18
    Changes: Refinement description