1OLS

Roles of His291-alpha and His146-beta' in the reductive acylation reaction catalyzed by human branched-chain alpha-ketoacid dehydrogenase


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.85 Å
  • R-Value Free: 0.199 
  • R-Value Work: 0.172 
  • R-Value Observed: 0.172 

Starting Model: experimental
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This is version 2.1 of the entry. See complete history


Literature

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

(2003) J Biol Chem 278: 43402

  • DOI: https://doi.org/10.1074/jbc.M306204200
  • Primary Citation of Related Structures:  
    1OLS, 1OLU, 1OLX

  • PubMed Abstract: 

    We report here that alterations of either His291-alpha or His146-beta' in the active site of human branched-chain alpha-ketoacid dehydrogenase (E1b) impede both the decarboxylation and the reductive acylation reactions catalyzed by E1b as well as the binding of cofactor thiamin diphosphate (ThDP). In a refined human E1b active-site structure, His291-alpha, which aligns with His407 in Escherichia coli pyruvate dehydrogenase and His263 in yeast transketolase, is on a largely ordered phosphorylation loop. The imidazole ring of His291-alpha in E1b coordinates to the terminal phosphate oxygen atoms of bound ThDP. The N3 atom of wild-type His146-beta', which can be protonated, binds a water molecule and points toward the aminopyrimidine ring of ThDP. Remarkably, the H291A-alpha mutation results in a complete order-to-disorder transition of the loop region, which precludes the binding of the substrate lipoyl-bearing domain to E1b. The H146A-beta' mutation, on the other hand, does not alter the loop structure, but nullifies the reductive acylation activity of E1b. Our results suggest that: 1) His291-alpha plays a structural rather than a catalytic role in the binding of cofactor ThDP and the lipoyl-bearing domain to E1b, and 2) His146-beta' is an essential catalytic residue, probably functioning as a proton donor in the reductive acylation of lipoamide on the lipoyl-bearing domain.


  • Organizational Affiliation

    Departments of Biochemistry and Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9038, USA.


Macromolecules
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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
2-OXOISOVALERATE DEHYDROGENASE ALPHA SUBUNIT400Homo sapiensMutation(s): 0 
EC: 1.2.4.4
UniProt & NIH Common Fund Data Resources
Find proteins for P12694 (Homo sapiens)
Explore P12694 
Go to UniProtKB:  P12694
PHAROS:  P12694
GTEx:  ENSG00000248098 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP12694
Sequence Annotations
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  • Reference Sequence
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 2
MoleculeChains Sequence LengthOrganismDetailsImage
2-OXOISOVALERATE DEHYDROGENASE BETA SUBUNIT342Homo sapiensMutation(s): 0 
EC: 1.2.4.4
UniProt & NIH Common Fund Data Resources
Find proteins for P21953 (Homo sapiens)
Explore P21953 
Go to UniProtKB:  P21953
PHAROS:  P21953
GTEx:  ENSG00000083123 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP21953
Sequence Annotations
Expand
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.85 Å
  • R-Value Free: 0.199 
  • R-Value Work: 0.172 
  • R-Value Observed: 0.172 
  • Space Group: P 31 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 144.721α = 90
b = 144.721β = 90
c = 69.151γ = 120
Software Package:
Software NamePurpose
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: 2003-08-15
    Type: Initial release
  • Version 1.1: 2011-05-08
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2019-05-15
    Changes: Data collection, Experimental preparation, Other
  • Version 1.4: 2019-09-25
    Changes: Data collection, Experimental preparation, Other
  • Version 2.0: 2021-08-04
    Changes: Atomic model, Data collection, Derived calculations, Non-polymer description, Structure summary
  • Version 2.1: 2023-12-13
    Changes: Data collection, Database references, Refinement description