The Crystal Structure of Candida glabrata THI6, a Bifunctional Enzyme involved in Thiamin Biosyhthesis of Eukaryotes

Experimental Data Snapshot

  • Resolution: 2.61 Å
  • R-Value Free: 0.271 
  • R-Value Work: 0.221 
  • R-Value Observed: 0.223 

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Domain Organization in Candida glabrata THI6, a Bifunctional Enzyme Required for Thiamin Biosynthesis in Eukaryotes .

Paul, D.Chatterjee, A.Begley, T.P.Ealick, S.E.

(2010) Biochemistry 49: 9922-9934

  • DOI: https://doi.org/10.1021/bi101008u
  • Primary Citation of Related Structures:  
    3NL2, 3NL3, 3NL5, 3NL6, 3NM1, 3NM3

  • PubMed Abstract: 

    THI6 is a bifunctional enzyme found in the thiamin biosynthetic pathway in eukaryotes. The N-terminal domain of THI6 catalyzes the ligation of the thiamin thiazole and pyrimidine moieties to form thiamin phosphate, and the C-terminal domain catalyzes the phosphorylation of 4-methyl-5-hydroxyethylthiazole in a salvage pathway. In prokaryotes, thiamin phosphate synthase and 4-methyl-5-hydroxyethylthiazole kinase are separate gene products. Here we report the first crystal structure of a eukaryotic THI6 along with several complexes that characterize the active sites responsible for the two chemical reactions. THI6 from Candida glabrata is a homohexamer in which the six protomers form a cage-like structure. Each protomer is composed of two domains, which are structurally homologous to their monofunctional bacterial counterparts. Two loop regions not found in the bacterial enzymes provide interactions between the two domains. The structures of different protein-ligand complexes define the thiazole and ATP binding sites of the 4-methyl-5-hydroxyethylthiazole kinase domain and the thiazole phosphate and 4-amino-5-hydroxymethyl-2-methylpyrimidine pyrophosphate binding sites of the thiamin phosphate synthase domain. Our structural studies reveal that the active sites of the two domains are 40 Å apart and are not connected by an obvious channel. Biochemical studies show 4-methyl-5-hydroxyethylthiazole phosphate is a substrate for THI6; however, adenosine diphospho-5β-ethyl-4-methylthiazole-2-carboxylic acid, the product of THI4, is not a substrate for THI6. This suggests that an unidentified enzyme is necessary to produce the substrate for THI6 from the THI4 product.

  • Organizational Affiliation

    Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853, United States.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Thiamine biosynthetic bifunctional enzyme
A, B, C
540Nakaseomyces glabratusMutation(s): 0 
Gene Names: CAGL0E05808gTHI6
EC: (PDB Primary Data), (PDB Primary Data)
Find proteins for Q6FV03 (Candida glabrata (strain ATCC 2001 / BCRC 20586 / JCM 3761 / NBRC 0622 / NRRL Y-65 / CBS 138))
Explore Q6FV03 
Go to UniProtKB:  Q6FV03
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ6FV03
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 3 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on ACP

Download Ideal Coordinates CCD File 
F [auth A],
I [auth B],
L [auth C]
C11 H18 N5 O12 P3
Query on TPS

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E [auth A],
H [auth B],
K [auth C]
C12 H18 N4 O4 P S
Query on MG

Download Ideal Coordinates CCD File 
D [auth A],
G [auth B],
J [auth C]
Experimental Data & Validation

Experimental Data

  • Resolution: 2.61 Å
  • R-Value Free: 0.271 
  • R-Value Work: 0.221 
  • R-Value Observed: 0.223 
  • Space Group: C 1 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 163.173α = 90
b = 153.528β = 117.99
c = 109.618γ = 90
Software Package:
Software NamePurpose
PDB_EXTRACTdata extraction

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2010-11-10
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2013-05-29
    Changes: Other
  • Version 1.3: 2024-02-21
    Changes: Data collection, Database references, Derived calculations