1V11

CROSSTALK BETWEEN COFACTOR BINDING AND THE PHOSPHORYLATION LOOP CONFORMATION IN THE BCKD MACHINE


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.95 Å
  • R-Value Free: 0.171 
  • R-Value Work: 0.138 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Cross-Talk between Thiamin Diphosphate Binding and Phosphorylation Loop Conformation in Human Branched-Chain {Alpha}-Keto Acid Decarboxylase/Dehydrogenase

Li, J.Wynn, R.M.Machius, M.Chuang, J.L.Karthikeyan, S.Tomchick, D.R.Chuang, D.T.

(2004) J.Biol.Chem. 279: 32968

  • DOI: 10.1074/jbc.M403611200
  • Primary Citation of Related Structures:  
  • Also Cited By: 2J9F, 2BFF, 2BFE, 2BFD, 2BFC, 2BFB, 2BEW, 2BEV, 2BEU, 1WCI

  • PubMed Abstract: 
  • The decarboxylase/dehydrogenase (E1b) component of the 4-megadalton human branched-chain alpha-keto acid dehydrogenase (BCKD) metabolic machine is a thiamin diphosphate (ThDP)-dependent enzyme with a heterotetrameric cofactor-binding fold. The E1b co ...

    The decarboxylase/dehydrogenase (E1b) component of the 4-megadalton human branched-chain alpha-keto acid dehydrogenase (BCKD) metabolic machine is a thiamin diphosphate (ThDP)-dependent enzyme with a heterotetrameric cofactor-binding fold. The E1b component catalyzes the decarboxylation of alpha-keto acids and the subsequent reductive acylation of the lipoic acid-bearing domain (LBD) from the 24-meric transacylase (E2b) core. In the present study, we show that the binding of cofactor ThDP to the E1b active site induces a disorder-to-order transition of the conserved phosphorylation loop carrying the two phosphorylation sites Ser(292)-alpha and Ser(302)-alpha, as deduced from the 1.80-1.85 A apoE1b and holoE1b structures. The induced loop conformation is essential for the recognition of lipoylated LBD to initiate E1b-catalyzed reductive acylation. Alterations of invariant Arg(287)-alpha, Asp(295)-alpha, Tyr(300)-alpha, and Arg(301)-alpha that form a hydrogen-bonding network in the phosphorylation loop result in the disordering of the loop conformation as elucidated by limited proteolysis, accompanied by the impaired binding and diminished reductive acylation of lipoylated LBD. In contrast, k(cat) values for E1b-catalyzed decarboxylation of the alpha-keto acid are higher in these E1b mutants than in wild-type E1b, with higher K(m) values for the substrate in the mutants. ThDP binding that orders the loop prevents phosphorylation of E1b by the BCKD kinase and averts the inactivation of wild-type E1b, but not the above mutants, by this covalent modification. Our results establish that the cross-talk between the bound ThDP and the phosphorylation loop conformation serves as a feed-forward switch for multiple reaction steps in the BCKD metabolic machine.


    Related Citations: 
    • Crystal Structure of Human Branched-Chain Alpha-Ketoacid Dehydrogenase and the Molecular Basis of Multienzyme Complex Deficiency in Maple Syrup Urine Disease
      Aevarsson, A.,Chuang, J.L.,Wynn, R.M.,Turley, S.,Chuang, D.T.,Hol, W.G.J.
      (2000) Structure 8: 277
    • 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
    • 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.
      (2003) J.Biol.Chem. 274: 4168


    Organizational Affiliation

    Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9038, USA.




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

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

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

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

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

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B
GLYCEROL
GLYCERIN; PROPANE-1,2,3-TRIOL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
 Ligand Interaction
BEN
Query on BEN

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Download CCD File 
A
BENZAMIDINE
C7 H8 N2
PXXJHWLDUBFPOL-UHFFFAOYSA-N
 Ligand Interaction
External Ligand Annotations 
IDBinding Affinity (Sequence Identity %)
TDPKd: 104800 nM BINDINGMOAD
TDPKd: 104800 nM PDBBIND
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.95 Å
  • R-Value Free: 0.171 
  • R-Value Work: 0.138 
  • Space Group: P 31 2 1
Unit Cell:
Length (Å)Angle (°)
a = 145.505α = 90.00
b = 145.505β = 90.00
c = 69.172γ = 120.00
Software Package:
Software NamePurpose
HKL-2000data scaling
REFMACrefinement
HKL-2000data reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2004-06-03
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Advisory, Version format compliance