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The crystal structure of yeast thiamin pyrophosphokinase.

BACKGROUND: Thiamin pyrophosphokinase (TPK) catalyzes the transfer of a pyrophosphate group from ATP to vitamin B1 (thiamin) to form the coenzyme thiamin pyrophosphate (TPP). Thus, TPK is important for the formation of a coenzyme required for central metabolic functions. TPK has no sequence homologs in the PDB and functions by an unknown mechanism. The TPK structure has been determined as a significant step toward elucidating its catalytic action. RESULTS: The crystal structure of Saccharomyces cerevisiae TPK complexed with thiamin has been determined at 1.8 A resolution. TPK is a homodimer, and each subunit consists of two domains. One domain resembles a Rossman fold with four alpha helices on each side of a 6 strand parallel beta sheet. The other domain has one 4 strand and one 6 strand antiparallel beta sheet, which form a flattened sandwich structure containing a jelly-roll topology. The active site is located in a cleft at the dimer interface and is formed from residues from domains of both subunits. The TPK dimer contains two compound active sites at the subunit interface. CONCLUSIONS: The structure of TPK with one substrate bound identifies the location of the thiamin binding site and probable catalytic residues. The structure also suggests a likely binding site for ATP. These findings are further supported by TPK sequence homologies. Although possessing no significant sequence homology with other pyrophospokinases, thiamin pyrophosphokinase may operate by a mechanism of pyrophosphoryl transfer similar to those described for pyrophosphokinases functioning in nucleotide biosynthesis.

Pubmed ID: 11435118

Authors

  • Baker LJ
  • Dorocke JA
  • Harris RA
  • Timm DE

Journal

Structure (London, England : 1993)

Publication Data

June 13, 2001

Associated Grants

  • Agency: NIDDK NIH HHS, Id: DK19259
  • Agency: NIDDK NIH HHS, Id: DK54738

Mesh Terms

  • Adenosine Triphosphate
  • Amino Acid Sequence
  • Binding Sites
  • Crystallography, X-Ray
  • Molecular Sequence Data
  • Protein Conformation
  • Saccharomyces cerevisiae
  • Sequence Homology, Amino Acid
  • Thiamin Pyrophosphokinase
  • Thiamine