Reduced expression of the proteolytically inactive FtsH members has impacts on the Darwinian fitness of Arabidopsis thaliana

Mishra, Laxmi S.; Mielke, Kati; Wagner, Raik; Funk, Christiane

doi:10.1093/jxb/erz004

Cited by 23 publications

(67 citation statements)

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“…The relevance of this question is reinforced due to the evolutionary history of FTSH proteins, during which a number of proteolytically inactive FTSHs (designated FTSHi) have been evolved. In the case of Arabidopsis, there are five such proteins, all of them are essential for development and growth (Sokolenko et al, 2002; Wagner et al, 2012; Mishra et al, 2019). Four of these have been recently identified in a large chloroplast complex, together with FTSH12, serving as a motor for protein import into chloroplasts (Kikuchi et al, 2018).…”

Section: Discussionmentioning

confidence: 99%

The Chloroplast Envelope Protease FTSH11 – Interaction With CPN60 and Identification of Potential Substrates

et al. 2019

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FTSH proteases are membrane-bound, ATP-dependent metalloproteases found in bacteria, mitochondria and chloroplasts. The product of one of the 12 genes encoding FTSH proteases in Arabidopsis, FTSH11, has been previously shown to be essential for acquired thermotolerance. However, the substrates of this protease, as well as the mechanism linking it to thermotolerance are largely unknown. To get insight into these, the FTSH11 knockout mutant was complemented with proteolytically active or inactive variants of this protease, tagged with HA-tag, under the control of the native promoter. Using these plants in thermotolerance assay demonstrated that the proteolytic activity, and not only the ATPase one, is essential for conferring thermotolerance. Immunoblot analyses of leaf extracts, isolated organelles and sub-fractionated chloroplast membranes localized FTSH11 mostly to chloroplast envelopes. Affinity purification followed by mass spectrometry analysis revealed interaction between FTSH11 and different components of the CPN60 chaperonin. In affinity enrichment assays, CPN60s as well as a number of envelope, stroma and thylakoid proteins were found associated with proteolytically inactive FTSH11. Comparative proteomic analysis of WT and knockout plants, grown at 20°C or exposed to 30°C for 6 h, revealed a plethora of upregulated chloroplast proteins in the knockout, some of them might be candidate substrates. Among these stood out TIC40, which was stabilized in the knockout line after recovery from heat stress, and three proteins that were found trapped in the affinity enrichment assay: the nucleotide antiporter PAPST2, the fatty acid binding protein FAP1 and the chaperone HSP70. The consistent behavior of these four proteins in different assays suggest that they are potential FTSH11 substrates.

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Section: Discussionmentioning

confidence: 99%

The Chloroplast Envelope Protease FTSH11 – Interaction With CPN60 and Identification of Potential Substrates

et al. 2019

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“…Relative transcript levels were determined by quantitative reverse transcription PCR (qRT–PCR) as described previously (Mishra et al , 2019), using the primers listed in Supplementary Table S2. RNA was extracted from the seedlings that were used to determine the impact of DEG10 and temperature on root growth.…”

Section: Methodsmentioning

confidence: 99%

DEG10 contributes to mitochondrial proteostasis, root growth, and seed yield in Arabidopsis

Huber

Jakobs

Mishra

et al. 2019

Journal of Experimental Botany

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Maintaining mitochondrial proteome integrity is especially important under stress conditions to ensure a continued ATP supply for protection and adaptation responses in plants. Deg/HtrA proteases are important factors in the cellular protein quality control system, but little is known about their function in mitochondria. Here we analyzed the expression pattern and physiological function of Arabidopsis thaliana DEG10, which has homologs in all photosynthetic eukaryotes. Both expression of DEG10:GFP fusion proteins and immunoblotting after cell fractionation showed an unambiguous subcellular localization exclusively in mitochondria. DEG10 promoter:GUS fusion constructs showed that DEG10 is expressed in trichomes but also in the vascular tissue of roots and aboveground organs. DEG10 loss-of-function mutants were impaired in root elongation, especially at elevated temperature. Quantitative proteome analysis revealed concomitant changes in the abundance of mitochondrial respiratory chain components and assembly factors, which partially appeared to depend on altered mitochondrial retrograde signaling. Under field conditions, lack of DEG10 caused a decrease in seed production. Taken together, our findings demonstrate that DEG10 affects mitochondrial proteostasis, is required for optimal root development and seed set under challenging environmental conditions, and thus contributes to stress tolerance of plants.

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“…While the location of FtsH11 ( Wagner et al , 2016 ) and FtsH12 ( Li et al , 2017 ) in the inner envelope could be confirmed, an unexpected localization of FtsHi4 in the thylakoid membrane has been reported ( Lu et al , 2014 ). With the exception of FTSHi 3, FTSHi knock-out mutants are embryo lethal ( Meinke et al , 2008 ), with reduced expression showing diminished Darwinian fitness ( Mishra et al , 2019 ). A point mutation in FTSHi1 that impaired its ATPase domain function ( ftsh1-1/arc1; Kadirjan-Kalbach et al , 2012 ) as well as knock-down mutants of FTSHi4 ( Lu et al , 2014 ) and FTSHi5 ( Wang et al , 2018 ) showed cotyledon and growth phenotypes, including alterations in chloroplast ultrastructure.…”

Section: Introductionmentioning

confidence: 99%

“…FtsH12 was thus suggested to be an essential component of an ATP-driven motor complex, while its proteolytic activity was reported to be dispensable ( Kikuchi et al , 2013 ). However, neither FtsH12 orthologues nor FtsHi are found in Poaceae ( Nakai, 2018 ; Mishra et al , 2019 ; Li et al , 2020 ), suggesting that it is not ubiquitous in all higher plants. Therefore, the importance of both the FtsH12-FtsHi complex and the interacting 1 MDa TIC complex for plastid protein import are subjects of a controversial debate ( Nakai, 2015 ; Agne et al , 2017 ; Bölter and Soll, 2017 ; Li et al , 2020 ; Nakai, 2020 ).…”

Section: Introductionmentioning

confidence: 99%

Abundance of metalloprotease FtsH12 modulates chloroplast development in Arabidopsis thaliana

Mielke

Wagner

Mishra

et al. 2020

Journal of Experimental Botany

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The ATP-dependent metalloprotease FtsH12 (filamentation temperature sensitive protein H 12) has been suggested to participate in a heteromeric motor complex, driving protein translocation into the chloroplast. FtsH12 was immuno-detected in proplastids, seedlings, leaves, and roots. Expression of Myc-tagged FtsH12 under its native promotor allowed identification of FtsHi1, 2, 4, and 5, and plastidic NAD-malate dehydrogenase, five of the six interaction partners in the suggested import motor complex. Arabidopsis thaliana mutant seedlings with reduced FTSH12 abundance exhibited pale cotyledons and small, deformed chloroplasts with altered thylakoid structure. Mature plants retained these chloroplast defects, resulting in slightly variegated leaves and lower chlorophyll content. Label-free proteomics revealed strong changes in the proteome composition of FTSH12 knock-down seedlings, reflecting impaired plastid development. The composition of the translocon on the inner chloroplast membrane (TIC) protein import complex was altered, with coordinated reduction of the FtsH12-FtsHi complex subunits and accumulation of the 1 MDa TIC complex subunits TIC56, TIC214 and TIC22-III. FTSH12 overexpressor lines showed no obvious phenotype, but still displayed distinct differences in their proteome. N-terminome analyses further demonstrated normal proteolytic maturation of plastid-imported proteins irrespective of FTSH12 abundance. Together, our data suggest that FtsH12 has highest impact during seedling development; its abundance alters the plastid import machinery and impairs chloroplast development.

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Reduced expression of the proteolytically inactive FtsH members has impacts on the Darwinian fitness of Arabidopsis thaliana

Abstract: The evolution of multiple genes encoding presumably proteolytically inactive filamentation-temperature-sensitive protein H (FtsHi) proteases accompanied the evolution of FTSH12 , and Arabidopsis mutants with reduced FTSHi expression show decreases in Darwinian fitness.

Cited by 23 publications

References 50 publications

The Chloroplast Envelope Protease FTSH11 – Interaction With CPN60 and Identification of Potential Substrates

The Chloroplast Envelope Protease FTSH11 – Interaction With CPN60 and Identification of Potential Substrates

DEG10 contributes to mitochondrial proteostasis, root growth, and seed yield in Arabidopsis

Abundance of metalloprotease FtsH12 modulates chloroplast development in Arabidopsis thaliana

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