GTPase activation of ATP sulfurylase

The mechanism

C. Liu, E. Martin, Thomas S. Leyh

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

ATP sulfurylase from Escherichia coli K12 catalyzes two, coupled reactions: the hydrolysis of GTP and the formation of activated sulfate (APS). At saturating levels of GTP, the initial rate of APS formation is stimulated 116-fold. The mechanism of this activation has been investigated using isotope trapping, mass spectrometry, and initial velocity kinetic techniques. In the presence of GTP, APS formation proceeds via nucleophilic attack of sulfate at the α-phosphoryl group of ATP. Isotope-trapping experiments demonstrate productive, random binding of ATP and GTP. ATP is hydrolyzed to yield AMP and PP(i) AMP production requires GTP and is suppressible by sulfate, suggesting GTP-dependent formation of an E*AMP intermediate in the synthesis of APS. Studies using the hydrolysis-resistant nucleotide analogues AMPCPP and GMPPNP demonstrate that GTP hydrolysis precedes scision of the α-β bond of ATP. Product inhibition studies indicate that PP(i) release occurs prior to the addition of sulfate and APS formation. These results are used to construct a proposed mechanism for the GTP-activated synthesis of APS.

Original languageEnglish (US)
Pages (from-to)2042-2047
Number of pages6
JournalBiochemistry
Volume33
Issue number8
StatePublished - 1994

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Sulfate Adenylyltransferase
GTP Phosphohydrolases
Guanosine Triphosphate
Chemical activation
Sulfates
Adenosine Monophosphate
Adenosine Triphosphate
Hydrolysis
Isotopes
Escherichia coli K12
Escherichia coli
Mass spectrometry
Mass Spectrometry
Nucleotides

ASJC Scopus subject areas

  • Biochemistry

Cite this

GTPase activation of ATP sulfurylase : The mechanism. / Liu, C.; Martin, E.; Leyh, Thomas S.

In: Biochemistry, Vol. 33, No. 8, 1994, p. 2042-2047.

Research output: Contribution to journalArticle

Liu, C, Martin, E & Leyh, TS 1994, 'GTPase activation of ATP sulfurylase: The mechanism', Biochemistry, vol. 33, no. 8, pp. 2042-2047.
Liu, C. ; Martin, E. ; Leyh, Thomas S. / GTPase activation of ATP sulfurylase : The mechanism. In: Biochemistry. 1994 ; Vol. 33, No. 8. pp. 2042-2047.
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