Reversible association of ribulose-1, 5-bisphosphate carboxylase/oxygenase activase with the thylakoid membrane depends upon the ATP level and pH in rice without heat stress

• Published in: Journal of experimental botany Vol. 61; no. 11; pp. 2939 - 2950
• Main Authors: Chen, Juan, Wang, Peng, Mi, Hua-ling, Chen, Gen-Yun, Xu, Da-Quan
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01.06.2010
• Subjects: Activation; Adenosine Triphosphate - metabolism; ATP; Biological and medical sciences; Enzyme Activation; Fluorescence; Fundamental and applied biological sciences. Psychology; Heat stress disorders; Hot Temperature; Hydrogen-Ion Concentration; Leaves; Oryza - enzymology; Oryza - genetics; Oryza - metabolism; Oryza sativa; Photosynthesis; Plant physiology; Plant Proteins - genetics; Plant Proteins - metabolism; Plants; Protein Binding; Protein isoforms; RESEARCH PAPER; Research Papers; Ribulose-Bisphosphate Carboxylase - genetics; Ribulose-Bisphosphate Carboxylase - metabolism; Rice; Rubisco; Rubisco activase; Stress, Physiological; thylakoid membrane; Thylakoids; Thylakoids - genetics; Thylakoids - metabolism; ΔpH; ΔpH; Monocotyledones; Enzyme; Ribulose-bisphosphate carboxylase; Rubisco; Lyases; Activation; Biomembrane; Rubisco activase; Thylakoid; Stress; Carbon-carbon lyases; Oryza; thylakoid membrane; Gramineae; Carboxy-lyases; Thermal shock; Angiospermae; Botany; pH; Herbaceous plant; Spermatophyta; ATP
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/erq122

Ribulose-1, 5-bisphosphate carboxylase/oxygenase (Rubisco) activase (RCA) in the thylakoid membrane (TM) has been shown to play a role in protection and regulation of photosynthesis under moderate heat stress. However, the physiological significance of RCA bound to the TM (TM–RCA) without heat stress remains unknown. In this study, it is first shown, using experiments in vivo, that the TM–RCA varies in rice leaves at different development stages, under different environmental conditions, and in a rice mutant. Furthermore, it is shown that the amount of TM–RCA always increased when the Rubisco activation state and the pH gradient across the TM (ΔpH) decreased. It was then demonstrated in vitro that the RCA bound dynamically to TM and the amount of TM–RCA increased during Rubisco activation. A high level of ATP and a high pH value promoted the dissociation of RCA from the TM. Both the RCA association with and dissociation from the TM showed conformational changes related to the ATP level or pH as indicated by the changes in fluorescence intensity of 1-anilinonaphthalene-8-sulphonic acid (ANS) binding to RCA. These results suggest that the reversible association of RCA with the TM is ATP and pH (or ΔpH) dependent; it might be involved in the RCA activation of Rubisco, in addition to the previously discovered role in the protection and regulation of photosynthesis under heat stress.