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The role of the chloroplast coupling factor in the inactivation of thylakoid membranes at low temperatures
Author(s) -
Santarius Kurt A.
Publication year - 1984
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1984.tb05175.x
Subject(s) - thylakoid , photophosphorylation , spinacia , membrane , chemistry , chloroplast , electrochemical gradient , biophysics , spinach , electron transport chain , biochemistry , biology , gene
Thylakoids isolated from spinach leaves ( Spinacia oleracea L. cv. Monatol) were exposed to variable low temperatures under non‐freezing conditions. After incubation, changes in the activities of several photochemical reactions and physical properties of the membranes were measured at room temperature. Cyclic photophosphorylation was strictly dependent on the temperature and the electrolyte concentration: decrease in temperature and increase in NaCl concentration enhanced membrane damage. Inactivation of photophosphorylation was accompanied by stimulation of non‐cyclic electron transport, increase in proton permeability and decrease in δpH. When dicyclohexylcarbodiimide was added, the proton gradient became completely restored. The temperature‐ and salt‐dependent breakdown of photophosporylation was closely related to the release of the chloroplast coupling factor (CF 1 ) from the membranes. The addition of Mg 2+ , very low concentrations of ATP or ADP, or higher concentrations of low‐molecular‐weight polyols prior to temperature treatment prevented thylakoid damage. The data indicate that inactivation of photophosphorylation of thylakoids at low temperatures is determined to a considerable extent by the cold lability of the CF 1 . As a consequence, it must be concluded that damage of biomembranes caused by freezing is not due solely to changes resulting from the ice formation but additionally by temperature‐dependent alterations of cold‐labile proteins. Moreover, the data explain the mechanism of non‐colligative cryoprotection of isolated thylakoid membranes.