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Indian Journal of Biochemistry and Biophysics (IJBB) >
IJBB Vol.45 [2008] >
IJBB Vol.45(4) [August 2008] >
| Title: | In vivo quality control of photosystem II in cyanobacteria Synechocystis sp. PCC 6803: D1 protein degradation and repair under the influence of light, heat and darkness |
| Authors: | Singh, Munna
Satoh, Kimiyuki
Yamamoto, Yasusi
Kanervo, Eira
Aro, Eva-Mari |
| Keywords: | D1 degradation
Photoinhibition
Protease
Photosystem II
Synechocystis sp. PCC 6803
Cyanobacteria |
| Issue Date: | Aug-2008 |
| Publisher: | CSIR |
| Abstract: | The cells of Synechocystis sp. PCC 6803 were subjected under photoinhibitory irradiation (600 μmolm⁻²s⁻¹) at various
temperatures (20-40°C) to study in vivo quality control of photosystem II (PSII). The protease biogenesis and its consequences
on photosynthetic efficiency (chlorophyll fluorescence ratio Fv/Fm) of the PSII, D1 degradation and repair were monitored
during illumination and darkness. The loss in Fv/Fm value and degradation of D1 protein occurred not only under high light
exposure, but also continued when the cells were subjected under dark restoration process after high light exposure. No loss in
Fv/Fm value or D1 degradation occurred during recovery under growth/low light (30 μmol m⁻² s⁻¹). Further, it helped the
resynthesis of new D1 protein, essential to sustain quality control of PSII. In vivo triggering of D1 protein required high light
exposure to switch-on the protease biosynthesis to maintain protease pool which induced temperature-dependent enzymatic
proteolysis of photodamaged D1 protein during photoinhition and dark incubation. Our findings suggested the involvement and
overexpression of a membrane-bound FtsH protease during high light exposure which caused degradation of D1 protein, strictly
regulated by high temperature (30-40ºC). However, lower temperature (20ºC) prevented further loss of photoinhibited PSII
efficiency in vivo and also retarded temperature-dependent proteolytic process of D1 degradation. |
| Page(s): | 237-243 |
| ISSN: | 0301-1208 |
| Source: | IJBB Vol.45(4) [August 2008]
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