Temperature effects on the allosteric transition of ATP sulfurylase from Penicillium chrysogenum

D. C. Medina, E. Hanna, I. J. MacRae, Andrew J Fisher, I. H. Segel

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4 Scopus citations


The effects of temperature on the initial velocity kinetics of allosteric ATP sulfurylase from Penicillium chrysogenum were measured. The experiments were prompted by the structural similarity between the C-terminal regulatory domain of fungal ATP sulfurylase and fungal APS kinase, a homodimer that undergoes a temperature-dependent, reversible dissociation of subunits over a narrow temperature range. Wild-type ATP sulfurylase yielded hyperbolic velocity curves between 18 and 30°C. Increasing the assay temperature above 30°C at a constant pH of 8.0 increased the cooperativity of the velocity curves. Hill coefficients (nH) up to 1.8 were observed at 42°C. The bireactant kinetics at 42°C were the same as those observed at 30°C in the presence of PAPS, the allosteric inhibitor. In contrast, yeast ATP sulfurylase yielded hyperbolic plots at 42°C. The P. chrysogenum mutant enzyme, C509S, which is intrinsically cooperative (nH = 1.8) at 30°C, became more cooperative as the temperature was increased yielding nH values up to 2.9 at 42°C. As the temperature was decreased, the cooperativity of C509S decreased; nH was 1.0 at 18°C. The cumulative results indicate that increasing the temperature increases the allosteric constant, L, i.e., promotes a shift in the base-level distribution of enzyme molecules from the high MgATP affinity R state toward the low MgATP affinity T state. As a result, the enzyme displays a true "temperature optimum" at subsaturating MgATP. The reversible temperature-dependent transitions of fungal ATP sulfurylase and APS kinase may play a role in energy conservation at high temperatures where the organism can survive but not grow optimally.

Original languageEnglish (US)
Pages (from-to)51-60
Number of pages10
JournalArchives of Biochemistry and Biophysics
Issue number1
StatePublished - Sep 1 2001


  • Allosteric behavior
  • Allosteric kinetics
  • ATP sulfurylase
  • Cooperativity
  • Kinetics
  • P. chrysogenum
  • Sulfurylase
  • Temperature effect
  • Temperature optimum

ASJC Scopus subject areas

  • Biochemistry
  • Biophysics
  • Molecular Biology


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