Determination of the genetic, molecular, and biochemical basis of the Arabidopsis thaliana thiamin auxotroph th1

Arch Biochem Biophys. 2007 Mar 1;459(1):107-14. doi: 10.1016/ Epub 2006 Nov 18.


2-methyl-4-amino-5-hydroxymethylpyrimidine phosphate kinase/thiamin monophosphate pyrophosphorylase (HMPPK/TMPPase) is a key enzyme involved in thiamin biosynthesis. A candidate HMPPK/TMPPase gene identified in the Arabidopsis genome complemented the thiamin auxotrophy of the th1 mutant, thus proving that the th1 locus corresponds to the structural gene for the HMPPK/TMPPase. Sequence comparisons between the wild-type HMPPK/TMPPase gene and the th1-201 mutant allele identified a single point mutation that caused the substitution of a phenylalanine for a conserved serine residue in the HMPPK domain. Functional analyses of the mutant HMPPK/TMPPase in Escherichia coli revealed that the amino acid substitution in the HMPPK domain of mutant enzyme resulted in a conformational change that severely compromised both activities of the bifunctional enzyme. Studies were also performed to identify the chloroplast as the specific subcellular locale of the Arabidopsis HMPPK/TMPPase.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Arabidopsis Proteins / chemistry*
  • Arabidopsis Proteins / genetics*
  • Arabidopsis Proteins / metabolism
  • Chloroplasts
  • Evolution, Molecular
  • Molecular Sequence Data
  • Phosphotransferases (Phosphate Group Acceptor) / chemistry*
  • Phosphotransferases (Phosphate Group Acceptor) / genetics*
  • Phosphotransferases (Phosphate Group Acceptor) / metabolism
  • Sequence Homology, Amino Acid
  • Thiamine / metabolism*
  • Thiamine Pyrophosphatase / chemistry*
  • Thiamine Pyrophosphatase / genetics*
  • Thiamine Pyrophosphatase / metabolism


  • Arabidopsis Proteins
  • 4-amino-5-(hydroxymethyl)-2-methylpyrimidine phosphate kinase
  • Phosphotransferases (Phosphate Group Acceptor)
  • Thiamine Pyrophosphatase
  • Thiamine