The crystal structure of yeast thiamin pyrophosphokinase

L. J. Baker, Jill A. Dorocke, Robert A. Harris, David E. Timm

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Abstract

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 Å resolution. TPK is a homodimer, and each subunit consists of two domains. One domain resembles a Rossman fold with four α helices on each side of a 6 strand parallel β sheet. The other domain has one 4 strand and one 6 strand antiparallel β 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.

Original languageEnglish (US)
Pages (from-to)539-546
Number of pages8
JournalStructure
Volume9
Issue number6
DOIs
StatePublished - Jan 1 2001

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Keywords

  • Metabolism
  • Multiwavelength anomalous dispersion
  • Pyrophosphokinase
  • Thiamin
  • X-ray crystallography

ASJC Scopus subject areas

  • Molecular Biology
  • Structural Biology

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