Abstract
Photosynthetic organisms are able to enhance the thermal stability of photosystem II (PSII) when they grow at moderately high temperatures. We studied molecular mechanisms responsible for the acclimation of PSII to high temperature in thylakoid membranes of suspension-cultured cells of soybean. The thermal stability of PSII in isolated thylakoid membranes was enhanced when the growth temperature was shifted from 25oC to 35oC. Disruption of the vesicular structure of thylakoid membrane with 0.05% Triton X-100 abolished the enhanced thermal stability. The components released by Triton X-100 from thylakoid membranes from cells grown at 35oC were able to increase the thermal stability of Triton-treated membranes. Boiling or filtration of the released components abolished the ability to increase thermal stability, suggesting that the active components should be proteins. Thus, proteins that are associated with thylakoid membranes might be involved in the enhancement of the thermal stability of PSII.
