Modulation of photosynthetic electron transport in the absence of terminal electron acceptors: Characterization of the rbcL deletion mutant of tobacco

Yagut Allahverdiyeva, Fikret Mamedov, Pirkko Mäenpää, Imre Vass, Eva Mari Aro

Research output: Contribution to journalArticle

56 Citations (Scopus)

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 ΔrbcL 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 ΔrbcL 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 ΔrbcL 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 ΔrbcL mutant under growth conditions. This protective capacity was rapidly exceeded in ΔrbcL mutant when the light level was elevated resulting in severe degradation of PSI complexes.

Original languageEnglish
Pages (from-to)69-83
Number of pages15
JournalBiochimica et Biophysica Acta - Bioenergetics
Volume1709
Issue number1
DOIs
Publication statusPublished - Aug 15 2005

Keywords

  • Photoinhibition
  • Photosynthesis
  • Photosystem I
  • Photosystem II
  • Rubisco

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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