The Variegated Mutants Lacking Chloroplastic FtsHs Are Defective in D1 Degradation and Accumulate Reactive Oxygen Species
Open Access
- 18 September 2009
- journal article
- Published by Oxford University Press (OUP) in Plant Physiology
- Vol. 151 (4), 1790-1801
- https://doi.org/10.1104/pp.109.146589
Abstract
In the photosynthetic apparatus, a major target of photodamage is the D1 reaction center protein of photosystem II (PSII). Photosynthetic organisms have developed a PSII repair cycle in which photodamaged D1 is selectively degraded. A thylakoid membrane-bound metalloprotease, FtsH, was shown to play a critical role in this process. Here, the effect of FtsHs in D1 degradation was investigated in Arabidopsis (Arabidopsis thaliana) mutants lacking FtsH2 (yellow variegated2 [var2]) or FtsH5 (var1). Because these mutants are characterized by variegated leaves that sometimes complicate biochemical studies, we employed another mutation, fu-gaeri1 (fug1), that suppresses leaf variegation in var1 and var2 to examine D1 degradation. Two-dimensional blue native PAGE showed that var2 has less PSII supercomplex and more PSII intermediate lacking CP43, termed RC47, than the wild type under normal growth light. Moreover, our histochemical and quantitative analyses revealed that chloroplasts in var2 accumulate significant levels of reactive oxygen species, such as superoxide radical and hydrogen peroxide. These results indicate that the lack of FtsH2 leads to impaired D1 degradation at the step of RC47 formation in PSII repair and to photooxidative stress even under nonphotoinhibitory conditions. Our in vivo D1 degradation assays, carried out by nonvariegated var2 fug1 and var1 fug1 leaves, demonstrated that D1 degradation was impaired in different light conditions. Taken together, our results suggest the important role of chloroplastic FtsHs, which was not precisely examined in vivo. Attenuated D1 degradation in the nonvariegated mutants also suggests that leaf variegation seems to be independent of the PSII repair.Keywords
This publication has 53 references indexed in Scilit:
- Mutations in SUPPRESSOR OF VARIEGATION1, a Factor Required for Normal Chloroplast Translation, Suppress var2-Mediated Leaf Variegation in ArabidopsisTHE PLANT CELL ONLINE, 2008
- Chlorophyll Fluorescence: A Probe of Photosynthesis In VivoAnnual Review of Plant Biology, 2008
- Distinct Functions for the Two PsbP-Like Proteins PPL1 and PPL2 in the Chloroplast Thylakoid Lumen of ArabidopsisPlant Physiology, 2007
- The Exposed N-Terminal Tail of the D1 Subunit Is Required for Rapid D1 Degradation during Photosystem II Repair inSynechocystissp PCC 6803THE PLANT CELL ONLINE, 2007
- Formation of DEG5 and DEG8 Complexes and Their Involvement in the Degradation of Photodamaged Photosystem II Reaction Center D1 Protein in ArabidopsisTHE PLANT CELL ONLINE, 2007
- White Leaf Sectors inyellow variegated2Are Formed by Viable Cells with Undifferentiated PlastidsPlant Physiology, 2007
- The Balance between Protein Synthesis and Degradation in Chloroplasts Determines Leaf Variegation inArabidopsis yellow variegatedMutantsTHE PLANT CELL ONLINE, 2007
- The Thylakoid Lumen Protease Deg1 Is Involved in the Repair of Photosystem II from Photoinhibition in ArabidopsisTHE PLANT CELL ONLINE, 2007
- Production and Scavenging of Reactive Oxygen Species in Chloroplasts and Their FunctionsPlant Physiology, 2006
- REACTIVE OXYGEN SPECIES: Metabolism, Oxidative Stress, and Signal TransductionAnnual Review of Plant Biology, 2004