2BFB

Reactivity modulation of human branched-chain alpha-ketoacid dehydrogenase by an internal molecular switch


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.77 Å
  • R-Value Free: 0.184 
  • R-Value Work: 0.145 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

A Versatile Conformational Switch Regulates Reactivity in Human Branched-Chain Alpha-Ketoacid Dehydrogenase.

Machius, M.Wynn, R.M.Chuang, J.L.Tomchick, D.R.Brautigam, C.A.Chuang, D.T.

(2006) Structure 14: 287

  • DOI: 10.1016/j.str.2005.10.009
  • Primary Citation of Related Structures:  
  • Also Cited By: 2J9F

  • PubMed Abstract: 
  • The dehydrogenase/decarboxylase (E1b) component of the 4 MD human branched-chain alpha-ketoacid dehydrogenase complex (BCKDC) is a thiamin diphosphate (ThDP)-dependent enzyme. We have determined the crystal structures of E1b with ThDP bound intermedi ...

    The dehydrogenase/decarboxylase (E1b) component of the 4 MD human branched-chain alpha-ketoacid dehydrogenase complex (BCKDC) is a thiamin diphosphate (ThDP)-dependent enzyme. We have determined the crystal structures of E1b with ThDP bound intermediates after decarboxylation of alpha-ketoacids. We show that a key tyrosine residue in the E1b active site functions as a conformational switch to reduce the reactivity of the ThDP cofactor through interactions with its thiazolium ring. The intermediates do not assume the often-postulated enamine state, but likely a carbanion state. The carbanion presumably facilitates the second E1b-catalyzed reaction, involving the transfer of an acyl moiety from the intermediate to a lipoic acid prosthetic group in the transacylase (E2b) component of the BCKDC. The tyrosine switch further remodels an E1b loop region to promote E1b binding to E2b. Our results illustrate the versatility of the tyrosine switch in coordinating the catalytic events in E1b by modulating the reactivity of reaction intermediates.


    Related Citations: 
    • Crosstalk between Cofactor Binding and the Phosphorylation Loop Conformation in the Bckd Machine
      Li, J.,Wynn, R.M.,Machius, M.,Chuang, J.L.,Karthikeyan, S.,Tomchick, D.R.,Chuang, D.T.
      (2004) J.Biol.Chem. 279: 32968
    • Roles of Active Site and Novel K+ Ion-Binding Site Residues in Human Mitochondrial Branched-Chain Alpha-Ketoacid Decarboxylase/Dehydrogenase
      Wynn, R.M.,Ho, R.,Chuang, J.L.,Chuang, D.T.
      (2001) J.Biol.Chem. 276: 4168
    • Roles of His291-Alpha and His146-Beta in the Reductive Acylation Reaction Catalyzed by Human Branched-Chain Alpha-Ketoacid Dehydrogenase: Refined Phosphorylation Loop Structure in the Active Site
      Wynn, R.,Machius, M.,Chuang, J.,Li, J.,Tomchick, D.,Chuang, D.
      (2003) J.Biol.Chem. 278: 43402


    Organizational Affiliation

    Department of Biochemistry, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, Texas 75390, USA. mischa.machius@utsouthwestern.edu




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
2-OXOISOVALERATE DEHYDROGENASE ALPHA SUBUNIT
A
400Homo sapiensMutation(s): 1 
Gene Names: BCKDHA
EC: 1.2.4.4
Find proteins for P12694 (Homo sapiens)
Go to Gene View: BCKDHA
Go to UniProtKB:  P12694
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
2-OXOISOVALERATE DEHYDROGENASE BETA SUBUNIT
B
342Homo sapiensMutation(s): 0 
Gene Names: BCKDHB
EC: 1.2.4.4
Find proteins for P21953 (Homo sapiens)
Go to Gene View: BCKDHB
Go to UniProtKB:  P21953
Small Molecules
Ligands 6 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
K
Query on K

Download SDF File 
Download CCD File 
A, B
POTASSIUM ION
K
NPYPAHLBTDXSSS-UHFFFAOYSA-N
 Ligand Interaction
MN
Query on MN

Download SDF File 
Download CCD File 
A
MANGANESE (II) ION
Mn
WAEMQWOKJMHJLA-UHFFFAOYSA-N
 Ligand Interaction
TDP
Query on TDP

Download SDF File 
Download CCD File 
A
THIAMIN DIPHOSPHATE
C12 H18 N4 O7 P2 S
AYEKOFBPNLCAJY-UHFFFAOYSA-N
 Ligand Interaction
CL
Query on CL

Download SDF File 
Download CCD File 
A
CHLORIDE ION
Cl
VEXZGXHMUGYJMC-UHFFFAOYSA-M
 Ligand Interaction
GOL
Query on GOL

Download SDF File 
Download CCD File 
B
GLYCEROL
GLYCERIN; PROPANE-1,2,3-TRIOL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
 Ligand Interaction
MRD
Query on MRD

Download SDF File 
Download CCD File 
B
(4R)-2-METHYLPENTANE-2,4-DIOL
C6 H14 O2
SVTBMSDMJJWYQN-RXMQYKEDSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.77 Å
  • R-Value Free: 0.184 
  • R-Value Work: 0.145 
  • Space Group: P 31 2 1
Unit Cell:
Length (Å)Angle (°)
a = 145.781α = 90.00
b = 145.781β = 90.00
c = 69.372γ = 120.00
Software Package:
Software NamePurpose
HKL-2000data reduction
REFMACrefinement
HKL-2000data scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2006-02-16
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Advisory, Version format compliance