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- Aigner, Harald, 1973-
(author)
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Characterization of FtsH proteases in the annual plant Arabidopsis thaliana
- 2012
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Doctoral thesis (other academic/artistic)abstract
- Background FtsH is an ATP-dependent membrane-bound metalloprotease. A. thaliana contains 12 FtsH proteases localized in membranes of chloroplasts and mitochondria where they form homo- or hetero-hexameric complexes. FtsH11 – the main subject of this thesis – is located in the chloroplast envelope. Methods Field studies with A. thaliana to determine Darwinian fitness. A growth under outdoor conditions often allows discovering of phenotypes that are unascertainable in the controlled environment of growth chambers. Proteomic methods to discover fragments of substrate proteins (limited proteolysis) and changes in the proteome of FtsH protease deficient mutants. Results ftsh11 has increased amount of: RuBisCO activase, several Calvin cycle enzymes, two enzymes involved in starch synthesis and some chaperons. Some of those enzymes have been identified as possible substrates of FtsH11. Under long photoperiods ftsh11 develops a chlorotic phenotype accompanied by decreasing NADP+/NADPH ratio and increase of ROS damaged proteins.
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| 2. |
- Aigner, Harald, 1973-
(author)
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Comparison of hypothetical 3D-structures of Arabidopsis thaliana FtsH Proteases with the aim to predict FtsH complex formation
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Other publication (other academic/artistic)abstract
- In Arabidopsis thaliana 12 metallo proteases of the FtsH family are located in the organellar membranes of chloroplasts and mitochondria. While it is known for the Arabidopsis FtsH proteases FtsH1, 2, 5 and 8 to form a hetero–oligomeric, hexameric complex in the chloroplast thylakoid membrane and for FtsH3 and 10 in the inner membrane of mitochondria, no data are available for the remaining (low abundant) FtsH proteases . We compared the sequence identity of amino acids predicted to be relevant in complex formation of FtsH proteases in order to predict additional hetero-oligomeric FtsH complexes. Focus was set on FtsH11 and FtsH4, two subunits that might form a complex in mitochondria.
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| 3. |
- Aigner, Harald, 1973-, et al.
(author)
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FtsH11 protease is required for Arabidopsis thaliana to adapt to gtowth in continuous light
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Other publication (other academic/artistic)abstract
- Continuous light can increase greenhouse food production; however, some of the most important greenhouse horticulture crops are not able to adapt to long photoperiods. Here, we provide evidence that knock-out of the FtsH11 protease causes molecular differences that prevent Arabidopsis thaliana to adapt to prolonged photoperiods. Previously this protease had been shown to be critical for thermotolerance (Chen et al. 2006). We demonstrate that knock-out mutants deficient of FtsH11 develop chlorosis when shifted to continuous light. When grown under normal growth conditions and short days, ftsh11 displayed changes in protein amount of chloroplast proteins involved in the photosynthetic light reaction and the Calvin cycle as well as of the FtsH12 protease. The proteomic changes are accompanied by reduced non-photochemical quenching and faster state transition. A shift to continuous light further enhanced these effects and induced morphological changes of the chloroplast and chlorosis. No changes in the mitochondrial proteome were observed between wild type and ftsh11.
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| 4. |
- Aigner, Harald, 1973-
(author)
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Searching for substrates of the metallo protease FtsH11 of Arabidopsis thaliana using N-terminal proteomics
- 2012
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Other publication (other academic/artistic)abstract
- FtsH11 is a membrane-bound metalloprotease localized in mitochondria and in the chloroplast envelope of Arabidopsis thaliana. An ftsh11 knock-out mutant has been shown to develop a chlorotic phenotype in prolonged photoperiods. The proteome of the ftsh11 chloroplast revealed increased abundance of several Calvin cycle enzymes, chaperones and some other proteins, however, none of those proteins could be verified to be an FtsH11 substrate (Harald Aigner, Raik Wagner, Lars L.E. Sjögren, Holger Eubel, A. Harvey Millar, Adrian K. Clarke, Christiane Funk, 2012, manuscript submitted). Here, we have used positional proteomics to identify peptides that report FtsH11 processing events. In this work we were able to identify seven chloroplast-localized proteins that are processed in wild type, but not in ftsh11.
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| 5. |
- Lâm, Xuân Tâm, 1986-, et al.
(author)
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Proteomic approaches to identify substrates of the three Deg/HtrA proteases of the cyanobacterium Synechocystis sp. PCC 6803
- 2015
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In: Biochemical Journal. - : Portland Press. - 0264-6021 .- 1470-8728. ; 468:3, s. 373-384
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Journal article (peer-reviewed)abstract
- The family of Deg/HtrA proteases plays an important role in quality control of cellular proteins in a wide range of organisms. In the genome of the cyanobacterium Synechocystis sp. PCC 6803, a model organism for photosynthetic research and renewable energy products, three Deg proteases are encoded, termed HhoA, HhoB and HtrA. In the present study, we compared wild-type (WT) Synechocystis cells with the single insertion mutants ΔhhoA, ΔhhoB and ΔhtrA. Protein expression of the remaining Deg/HtrA proteases was strongly affected in the single insertion mutants. Detailed proteomic studies using DIGE (difference gel electrophoresis) and N-terminal COFRADIC (N-terminal combined fractional diagonal chromatography) revealed that inactivation of a single Deg protease has similar impact on the proteomes of the three mutants; differences to WT were observed in enzymes involved in the major metabolic pathways. Changes in the amount of phosphate permease system Pst-1 were observed only in the insertion mutant ΔhhoB. N-terminal COFRADIC analyses on cell lysates of ΔhhoB confirmed changed amounts of many cell envelope proteins, including the phosphate permease systems, compared with WT. In vitro COFRADIC studies were performed to identify the specificity profiles of the recombinant proteases rHhoA, rHhoB or rHtrA added to the Synechocystis WT proteome. The combined in vivo and in vitro N-terminal COFRADIC datasets propose RbcS as a natural substrate for HhoA, PsbO for HhoB and HtrA and Pbp8 for HtrA. We therefore suggest that each Synechocystis Deg protease protects the cell through different, but connected mechanisms.
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| 6. |
- Wagner, Raik, 1976-, et al.
(author)
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Fitness analyses of Arabidopsis thaliana mutants depleted of FtsH metalloproteases and characterization of three FtsH6 deletion mutants exposed to high light stress, senescence and chilling
- 2011
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In: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 191:2, s. 449-458
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Journal article (peer-reviewed)abstract
- Darwinian fitness analyses were performed, comparing single ftsh mutants with wild-type Arabidopsis thaliana plants grown under controlled laboratory conditions and in the field, by measuring plant size, survival rate, and silique and seed production. Additionally, three genotypes of ΔFtsH6 were analysed, under controlled growth conditions, with respect to both their ability to degrade the light-harvesting complex of photosystem II during senescence and light acclimation. In the field, substantial increases in variegation and reductions in growth were observed in the ΔFtsH2, ΔFtsH5 and ΔFtsH10 mutants; FtsH2 seemed particularly important for plant survival. Despite being grown in relatively cold weather, the ΔFtsH11 mutant displayed strong phenotypic deviations from wild type. Both ΔFtsH10 and ΔFtsH3 mutants exhibited less severe phenotypic changes, but were different from wild-type plants when placed in the field as young plants. When older ΔFtsH3 or ΔFtsH10 mutants were placed outdoors, no phenotypic differences from wild type were observed. Three genotypes of ΔFtsH6 displayed no phenotypic deviations from wild-type plants. Under controlled growth conditions, during senescence and light acclimation, no differences in the amount of chlorophyll or Photosystem II light-harvesting complex b3 (Lhcb3) were detected in ΔFtsH6 mutants compared with the wild type. Therefore, FtsH6 seems to be unimportant for LHCII degradation in vivo.
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| 7. |
- Wagner, Raik, 1976-, et al.
(author)
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FtsH proteases located in the plant chloroplast
- 2012
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In: Physiologia Plantarum. - Oxford : Wiley-Blackwell. - 0031-9317 .- 1399-3054. ; 145:1, s. 203-214
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Journal article (peer-reviewed)abstract
- FtsHs are a well-characterized family of membrane bound proteases containing an AAA (ATPase associated with various cellular activities) and a Zn2+ metalloprotease domain. FtsH proteases are found in eubacteria, animals and plants, and are known to have a crucial role in housekeeping proteolysis of membrane proteins. In Arabidopsis thaliana 12 FtsH family members are present (FtsH 1–12) and their subcellular localization is restricted to mitochondria and chloroplasts. In addition, five genes coding for proteins homologous to FtsH (FtsHi 1–5) have been detected in the genome, lacking the conserved zinc-binding motif HEXXH, which presumably renders them inactive for proteolysis. These inactive FtsHs as well as nine of the active FtsHs are thought to be localized in the chloroplast. In this minireview we shortly summarize the recent findings on plastidic FtsH proteases in text and figures. We will mainly focus on FtsH 1, 2, 5 and 8, localized in the thylakoid membrane and known for their importance in photosynthesis.
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