Structural changes associated with the acute thermal instability of Rubisco activase

Csengele Barta, Alison M. Dunkle, Rebekka Wachter, Michael E. Salvucci

Research output: Contribution to journalArticle

32 Scopus citations

Abstract

Inhibition of photosynthesis by heat has been linked to the instability of the ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) chaperone, Rubisco activase. Examination of the recombinant enzyme showed that ADP and ATP protected against inactivation, whereas Mg2+ promoted inactivation. Heating caused aggregation of Rubisco activase characterized by disruption of secondary structure content and formation of insoluble protein. In contrast, incubation at room temperature without nucleotide caused the active ∼660kDa protein to form a soluble, but inactive aggregate of >2×106Da. Circular dichroism (CD) spectroscopy and fluorescence established that structural perturbations in the aggregate did not reduce alpha-helical content significantly. Differences in the thermal stability between wild type and mutant Rubisco activase were observed for the recombinant proteins and when the proteins were expressed in transgenic Arabidopsis. That the sensitivity of these plants to heat differs indicates that the thermal instability of Rubisco activase is a main determinant of the temperature-sensitivity of photosynthesis.

Original languageEnglish (US)
Pages (from-to)17-25
Number of pages9
JournalArchives of Biochemistry and Biophysics
Volume499
Issue number1-2
DOIs
StatePublished - Jul 1 2010

Keywords

  • Adenine nucleotides
  • Calvin cycle
  • Heat stress
  • Magnesium ions
  • Photosynthetic CO fixation
  • Thermal stability

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology

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