期刊
BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS
卷 1797, 期 1, 页码 63-70出版社
ELSEVIER
DOI: 10.1016/j.bbabio.2009.08.001
关键词
Chlorophyll-containing protein complex; Chlorophyll fluorescence temperature curve, Disassembly; Heat denaturation; High temperature; Native electrophoresis
资金
- Ministry of Education, Youth and Sports of the Czech Republic [MSM 6198959215]
Gradual heating of green leaves up to non-physiological temperatures is often used to estimate thermal stability of photosynthetic apparatus. However, a complete sequence of heat-induced disassembly and denaturation of chlorophyll-containing protein complexes (CPCs) has not been reported yet. In this work, we heated (1 degrees C.min(-1)) barley leaves to temperatures selected according to the changes in the chlorophyll fluorescence temperature curve (FTC) and we analyzed CPC stability by two-dimensional native Deriphat/SDS-PAGE. The first distinct change in both structure and function of photosystem II (PSII) appeared at 4050 degrees C. PSII core (CCII) dimers began to dissociate monomers, which was accompanied by a decrease in PSII photochemistry and reflected in FTC as the first fluorescence increase. Further changes in CPCs appeared at 57-60 degrees C, when FTC increases to its second maximum. Photosystem I (PSI) cores4 (CCI) partially dissociated from light-harvesting complexes of PSI (LHCI) and formed aggregates. The rest of CCI-LHCI complexes, as well as the CCI aggregates, degraded to the PSI-A/B heterodimer in leaves heated to 70 degrees C. Heating to these temperatures led to a complete degradation of CCII components and corresponding loss of PSII photochemistry. Trimeric light-harvesting complexes of PSII (LHCII) markedly dissociated to monomers and denatured, as evidenced by a release of large amount of free chlorophylls. Between 70 and 80 degrees C, a complete degradation of LHCII occurred, leaving the PSI-A/B heterodimer as the only detectable CPC in the membrane. This most thermostable CPC disappeared after heating to 90 degrees C. which corresponded to a loss of PSI photochemistry. (C) 2009 Elsevier B.V. All rights reserved.
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