Kinetic properties of ATP sulfurylase and APS kinase from Thiobacillus denitrificans

Sean C. Gay, Jennifer L. Fribourgh, Paul D. Donohoue, Irwin H. Segel, Andrew J Fisher

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


The Thiobacillus denitrificans genome contains two sequences corresponding to ATP sulfurylase (Tbd_0210 and Tbd_0874). Both genes were cloned and expressed protein characterized. The larger protein (Tbd_0210; 544 residues) possesses an N-terminal ATP sulfurylase domain and a C-terminal APS kinase domain and was therefore annotated as a bifunctional enzyme. But, the protein was not bifunctional because it lacked ATP sulfurylase activity. However, the enzyme did possess APS kinase activity and displayed substrate inhibition by APS. Truncated protein missing the N-terminal domain had <2% APS kinase activity suggesting the function of the inactive sulfurylase domain is to promote the oligomerization of the APS kinase domains. The smaller gene product (Tbd_0874; 402 residues) possessed strong ATP sulfurylase activity with kinetic properties that appear to be kinetically optimized for the direction of APS utilization and ATP + sulfate production, which is consistent with an enzyme that functions physiologically to produce inorganic sulfate.

Original languageEnglish (US)
Pages (from-to)110-117
Number of pages8
JournalArchives of Biochemistry and Biophysics
Issue number1-2
StatePublished - Sep 2009


  • APS kinase, from Thiobacillus
  • ATP sulfurylase, from Thiobacillus
  • Chemolithotrophic
  • Enzyme kinetics
  • Kinase, APS, from Thiobacillus
  • Sulfate activating enzyme, from Thiobacillus
  • Sulfate formation, by Thiobacillus
  • Sulfate metabolism
  • Sulfurylase, ATP, from Thiobacillus
  • Thiobacillus denitrificans, ATP sulfurylase, from Thiobacillus

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology


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