Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10796108 | Biochimica et Biophysica Acta (BBA) - Bioenergetics | 2005 | 15 Pages |
Abstract
Tobacco rbcL deletion mutant, which lacks the key enzyme Rubisco for photosynthetic carbon assimilation, was characterized with respect to thylakoid functional properties and protein composition. The ÎrbcL plants showed an enhanced capacity for dissipation of light energy by non-photochemical quenching which was accompanied by low photochemical quenching and low overall photosynthetic electron transport rate. Flash-induced fluorescence relaxation and thermoluminescence measurements revealed a slow electron transfer and decreased redox gap between QA and QB, whereas the donor side function of the Photosystem II (PSII) complex was not affected. The 77 K fluorescence emission spectrum of ÎrbcL plant thylakoids implied a presence of free light harvesting complexes. Mutant plants also had a low amount of photooxidisible P700 and an increased ratio of PSII to Photosystem I (PSI). On the other hand, an elevated level of plastid terminal oxidase and the lack of F0 'dark rise' in fluorescence measurements suggest an enhanced plastid terminal oxidase-mediated electron flow to O2 in ÎrbcL thylakoids. Modified electron transfer routes together with flexible dissipation of excitation energy through PSII probably have a crucial role in protection of PSI from irreversible protein damage in the ÎrbcL mutant under growth conditions. This protective capacity was rapidly exceeded in ÎrbcL mutant when the light level was elevated resulting in severe degradation of PSI complexes.
Keywords
ETR2,6-dimethyl-p-benzoquinoneferredoxin-NADP oxidoreductaseDMBQribulose-1,5-biphosphate carboxylase/oxygenaseCP29NDH-1P700P680PTOXDCMULHCIIFNRNPQChlPSIIPSIDABRuBisCO3-(3,4-Dichlorophenyl)-1,1-dimethylurea3,3′-diaminobenzidineQA and QBROSEPRElectron paramagnetic resonanceNon-photochemical quenchingChlorophyllcytcytochromephotosystem IPhotoinhibitionPhotosynthesisPhotosystem IIElectron transport ratewild typeplastid terminal oxidaseplastoquinoneThermoluminescenceReactive oxygen species
Related Topics
Life Sciences
Agricultural and Biological Sciences
Plant Science
Authors
Yagut Allahverdiyeva, Fikret Mamedov, Pirkko Mäenpää, Imre Vass, Eva-Mari Aro,