2HG8

Crystal Structure of Cys315Ala mutant of human mitochondrial branched chain aminotransferase complexed with its substrate mimic, N-methyl leucine.


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.8 Å
  • R-Value Free: 0.282 
  • R-Value Work: 0.252 

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, 2HGW, 2HGX, 2HHF

  • 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-O ...

    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.


    Related Citations: 
    • Cloning of the rat and human mitochondrial branched chain aminotransferases (BCATm).
      Bledsoe, R.K.,Dawson, P.A.,Hutson, S.M.
      (1997) Biochim.Biophys.Acta 1339: 9
    • Overexpression and characterization of the human mitochondrial and cytosolic branched-chain aminotransferases.
      Davoodi, J.,Drown, P.M.,Bledsoe, R.K.,Wallin, R.,Reinhart, G.D.,Hutson, S.M.
      (1998) J.BIOL.CHEM. 273: 4982


    Organizational Affiliation

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




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Branched-chain-amino-acid aminotransferase, mitochondrial
A, B
365Homo sapiensGene Names: BCAT2 (BCATM, BCT2, ECA40)
EC: 2.6.1.42
Find proteins for O15382 (Homo sapiens)
Go to Gene View: BCAT2
Go to UniProtKB:  O15382
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
MLE
Query on MLE

Download SDF File 
Download CCD File 
A
N-METHYLLEUCINE
C7 H15 N O2
XJODGRWDFZVTKW-LURJTMIESA-N
 Ligand Interaction
ACY
Query on ACY

Download SDF File 
Download CCD File 
A
ACETIC ACID
C2 H4 O2
QTBSBXVTEAMEQO-UHFFFAOYSA-N
 Ligand Interaction
PLP
Query on PLP

Download SDF File 
Download CCD File 
A, B
PYRIDOXAL-5'-PHOSPHATE
VITAMIN B6 Phosphate
C8 H10 N O6 P
NGVDGCNFYWLIFO-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.8 Å
  • R-Value Free: 0.282 
  • R-Value Work: 0.252 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 59.179α = 90.00
b = 109.278β = 97.23
c = 59.449γ = 90.00
Software Package:
Software NamePurpose
AMoREphasing
DENZOdata reduction
PDB_EXTRACTdata extraction
CNSrefinement
SCALEPACKdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

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