The chaperonin protein cpn60 from Escherichia coli protects the monomeric, mitochondrial enzyme rhodanese (thiosulfate:cyanide sulfurtransferase, EC 126.96.36.199) against heat inactivation. The thermal inactivation of rhodanese was studied for four different states of the enzyme: native, refolded, bound to cpn60 in the form of a binary complex formed from unfolded rhodanese, and a thermally perturbed state. Thermal stabilization is observed in a range of temperatures from 25 to 48 °C. Rhodanese that had been inactivated by incubation at 48 °C, in the presence of cpn60 can be reactivated at 25 °C, upon addition of cpn10, K+, and MgATP. A recovery of about 80% was achieved after 1 h of the addition of those components. Thus, the enzyme is protected against heat inactivation and kept in a reactivable form if inactivation is attempted using the binary complex formed between rhodanese folding intermediate(s) and cpn60. The chaperonin-assisted refolding of urea- denatured rhodanese is dependent on the temperature of the refolding reaction. However, optimal chaperonin assisted refolding of rhodanese observed at 25 °C, which is achieved upon addition of cpn10 and ATP to the cpn60-rhodanese complex, is independent of the temperature of preincubation of the complex, that was formed previously at low temperature. The results are in agreement with a model in which the chaperonin cpn60 interacts with partly folded intermediates by forming a binary complex which is stable to elevated temperatures. In addition, it appears that native rhodanese can be thermally perturbed to produce a state different from that achieved by denaturation that can interact with cpn60.
|Original language||English (US)|
|Number of pages||4|
|Journal||Journal of Biological Chemistry|
|State||Published - 1992|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology