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| Open AccessPlastid ancestors lacked a complete Entner-Doudoroff pathway, limiting plants to glycolysis and the pentose phosphate pathway
The Enter-Doudoroff (ED) pathway is an alternative to glycolysis present in some prokaryotes. Evans et al. show that its dehydratase enzyme, evolved from a branched chain amino acid pathway paralog, acquired a new function through mutations in its active site.
- Sonia E. Evans
- , Anya E. Franks
- & Michael A. Phillips
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| Open AccessAdjustment of light-responsive NADP dynamics in chloroplasts by stromal pH
NADP+ is the final electron acceptor for linear electron transfer in photosynthesis. Here, the authors show that the NADP pool size is modulated by its interconversion with NAD via ΔpH regulation in response to varying light conditions.
- Yusuke Fukuda
- , Chinami Ishiyama
- & Shin-nosuke Hashida
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| Open AccessWeak acids produced during anaerobic respiration suppress both photosynthesis and aerobic respiration
The processes of photosynthesis, aerobic and anaerobic respiration (fermentation) power life on Earth. Here, using mainly green alga Chlamydomonas, the authors find that the weak acids produced during fermentation could chemically suppress both photosynthesis and aerobic respiration.
- Xiaojie Pang
- , Wojciech J. Nawrocki
- & Lijin Tian
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| Open AccessAnterograde signaling controls plastid transcription via sigma factors separately from nuclear photosynthesis genes
Photoreceptors in the nucleus control plastid transcription by utilizing sigma factors as nucleus-to-plastid signals in parallel with the light regulation of nuclear photosynthesis genes.
- Youra Hwang
- , Soeun Han
- & Meng Chen
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Article
| Open AccessDe-etiolation-induced protein 1 (DEIP1) mediates assembly of the cytochrome b6f complex in Arabidopsis
The Cytb6f complex is a multi-subunit enzyme that couples the two photosystems during the light reactions of photosynthesis. Here the authors show that the thylakoid-localized DEIP1 protein interacts with the PetA and PetB subunits, and is essential for Cytb6f complex assembly in Arabidopsis.
- Omar Sandoval-Ibáñez
- , David Rolo
- & Ralph Bock
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| Open AccessSex-linked deubiquitinase establishes uniparental transmission of chloroplast DNA
Most sexual organisms ensure that organelles are inherited from a single parent. Here, the authors describe OTU2p, a Chlamydomonas deubiquitinase that drives uniparental organelle inheritance without gametic dimorphism by preventing proteasome-mediated degradation exclusively in gametes of the plus mating type.
- Sunjoo Joo
- , Thamali Kariyawasam
- & Jae-Hyeok Lee
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Article
| Open AccessArabidopsis guard cell chloroplasts import cytosolic ATP for starch turnover and stomatal opening
Stomatal guard cells require ATP in order to fuel stomatal movements. Here the authors show that guard cell photosynthesis is limited, mitochondria are the main source of ATP and that guard cell chloroplasts import ATP via nucleotide transporters.
- Shey-Li Lim
- , Sabrina Flütsch
- & Boon Leong Lim
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| Open AccessNuA4 and H2A.Z control environmental responses and autotrophic growth in Arabidopsis
Function of nucleosomal acetyltransferase of H4 (NuA4), one major complex of HAT, remains unclear in plants. Here, the authors generate mutants targeting two components of the putative NuA4 complex in Arabidopsis (EAF1 and EPL1) and show their roles in photosynthesis genes regulation through H4K5ac and H2A.Z acetylation.
- Tomasz Bieluszewski
- , Weronika Sura
- & Piotr A. Ziolkowski
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Article
| Open AccessInterdependent iron and phosphorus availability controls photosynthesis through retrograde signaling
Iron deficiency induces chlorosis in plants but only when phosphate supply is sufficient. Here, the authors show that phosphate-dependency is governed by a ROS-mediated retrograde signaling pathway involving the PHT4;4 chloroplast ascorbate transporter and the bZIP58 nuclear transcription factor.
- Hye-In Nam
- , Zaigham Shahzad
- & Hatem Rouached
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| Open AccessCoalescence and directed anisotropic growth of starch granule initials in subdomains of Arabidopsis thaliana chloroplasts
Starch is the major form of energy storage in plant cells and forms discrete, semi-crystalline granules within plastids. Here the authors use electron tomography and nanoSIMS to show that Arabidopsis starch granules initiate in stromal pockets between thylakoid membranes that coalesce before growing anisotropically.
- Léo Bürgy
- , Simona Eicke
- & Samuel C. Zeeman
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| Open AccessSingle cell genomics reveals plastid-lacking Picozoa are close relatives of red algae
The origin of primary plastids in an ancestor of Archaeplastida gave eukaryotes photosynthetic capabilities. This study used single-cell genomics and phylogenomics to infer the evolutionary origin of the plastid-lacking phylum Picozoa, a group of marine microbial heterotrophic eukaryotes, showing that they belong to the Archaeplastida and changing our understanding of plastid evolution.
- Max E. Schön
- , Vasily V. Zlatogursky
- & Fabien Burki
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| Open AccessPGRL2 triggers degradation of PGR5 in the absence of PGRL1
It is currently thought that the thylakoid proteins PGRL1 and PGR5 form a complex to mediate cyclic electron flow (CEF) around photosystem I. Here the authors show that CEF can in fact be mediated by PGR5 alone and that PGRL1 and the homologous PGRL2 modify the process by modulating PGR5 activity and stability.
- Thilo Rühle
- , Marcel Dann
- & Dario Leister
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| Open AccessEpidermal chloroplasts are defense-related motile organelles equipped with plant immune components
Leaf epidermal cells contain small chloroplasts which likely contribute little to photosynthesis and whose function is unclear. Here the authors show that these chloroplasts move toward the leaf surface in response to invasion trials by non-adapted fungal pathogens and contribute to non-host resistance.
- Hiroki Irieda
- & Yoshitaka Takano
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| Open AccessA molecular timescale for eukaryote evolution with implications for the origin of red algal-derived plastids
There are several competing hypotheses for the acquisition of red algal-derived plastids by eukaryotic phytoplankton. Here, the authors use Bayesian molecular clock analyses to evaluate the chronological possibility of the proposed plastid origins and transmissions.
- Jürgen F. H. Strassert
- , Iker Irisarri
- & Fabien Burki
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| Open AccessRETRACTED ARTICLE:The Arabidopsis NOT4A E3 ligase promotes PGR3 expression and regulates chloroplast translation
NOT4 proteins associate with ribosomes and are required for co-translational quality control in yeast and animals. Here, Bailey et al. show that Arabidopsis NOT4A positively regulates the expression of the nuclear encoded pentatricopeptide repeat (PPR) protein PGR3 and is required for ribosome biogenesis and mRNA translation in the chloroplast.
- Mark Bailey
- , Aiste Ivanauskaite
- & Daniel J. Gibbs
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| Open AccessIn planta study of photosynthesis and photorespiration using NADPH and NADH/NAD+ fluorescent protein sensors
NADP(H) and NAD(H) are crucial energy molecules in plant metabolism. Here, via the use of circularly permutated fluorescent protein sensors, the authors demonstrate dynamic changes in NADPH and the NADH/NAD+ ratio during photosynthesis and photorespiration at the subcellular level in planta.
- Shey-Li Lim
- , Chia Pao Voon
- & Boon Leong Lim
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| Open AccessTargeted delivery of nanomaterials with chemical cargoes in plants enabled by a biorecognition motif
Targeted delivery of nanomaterials to subcellular compartments could allow precision engineering of plant function. Here, Santana et al. show that quantum dots functionalized with a rationally-designed targeting peptide are preferentially delivered to chloroplasts where they can be used to tune organellar redox status.
- Israel Santana
- , Honghong Wu
- & Juan Pablo Giraldo
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| Open AccessMild proteasomal stress improves photosynthetic performance in Arabidopsis chloroplasts
Most chloroplast proteins are imported from the cytosol and thus transiently exposed to the cytosolic proteasome. Here the authors show that impairment of the cytosolic proteasome can elevate precursor protein abundance and photosynthetic activity suggesting that cytosolic protein turnover is a means to tune plastid function.
- Julia Grimmer
- , Stefan Helm
- & Sacha Baginsky
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| Open AccessOrthogonal regulation of phytochrome B abundance by stress-specific plastidial retrograde signaling metabolite
MEcPP is an evolutionarily conserved metabolite that acts as a plastid-to-nucleus retrograde signal to regulate adaptive responses to fluctuating light. Here the authors show that MEcPP regulates seedling development by stabilizing the phyB photoreceptor in an auxin and Ca2+ dependent manner.
- Jishan Jiang
- , Liping Zeng
- & Katayoon Dehesh
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| Open AccessOxidative post-translational modification of EXECUTER1 is required for singlet oxygen sensing in plastids
Singlet oxygen generated by photosynthesis under photo-oxidative stress conditions triggers retrograde signaling from plastids to nuclei. Here, the authors show that singlet oxygen perception and subsequent signaling events require oxidative post-translational modification of the EXECUTER1 protein.
- Vivek Dogra
- , Mingyue Li
- & Chanhong Kim
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| Open AccessNCP activates chloroplast transcription by controlling phytochrome-dependent dual nuclear and plastidial switches
Phytochrome signaling in the nucleus can activate expression of photosynthesis-associated genes in plastids. Here Yang et al. show that NCP is a dual-targeted protein that promotes phytochrome B localization to photobodies in the nucleus while facilitating PEP polymerase assembly in the plastids.
- Emily J. Yang
- , Chan Yul Yoo
- & Meng Chen
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| Open AccessPhytochrome activates the plastid-encoded RNA polymerase for chloroplast biogenesis via nucleus-to-plastid signaling
Light initiates chloroplast biogenesis by controlling gene expression in plastids. Here Yoo et al. show that nuclear phytochrome signaling triggers plastid gene expression via a novel dual-localized protein necessary for nuclear phytochrome signaling and subsequent anterograde signaling to the plastid.
- Chan Yul Yoo
- , Elise K. Pasoreck
- & Meng Chen
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| Open AccessInterplay of the two ancient metabolites auxin and MEcPP regulates adaptive growth
MEcPP is an evolutionarily conserved plastidial metabolite functioning as a retrograde signal to the nucleus in response to environmental stresses. Here Jiang et al. show that MEcPP can reduce the abundance of auxin and an auxin transporter, providing a mechanistic link between plastids and adaptive growth responses.
- Jishan Jiang
- , Cecilia Rodriguez-Furlan
- & Katayoon Dehesh
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| Open AccessRedox regulation of PEP activity during seedling establishment in Arabidopsis thaliana
The plastid-encoded RNA polymerase PEP is regulated according to plastid redox state. Here, the authors show that the redox-regulated PRIN2 protein is reduced to monomeric form in a thiol-dependent manner in response to light and that PRIN2 monomers are required for PEP activity and retrograde signaling.
- Manuel Guinea Díaz
- , Tamara Hernández-Verdeja
- & Åsa Strand
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Article
| Open AccessPlastid-nucleus communication involves calcium-modulated MAPK signalling
Retrograde signalling co-ordinates nuclear gene expression in response to stress perceived in the chloroplast. Here Guo et al. show that a MAPK cascade acting downstream of a plastid derived Ca2+signal contributes to the regulation of nuclear gene expression by phosphorylation of ABI4 during retrograde signalling.
- Hailong Guo
- , Peiqiang Feng
- & Lixin Zhang
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Article
| Open AccessStructural basis for cpSRP43 chromodomain selectivity and dynamics in Alb3 insertase interaction
The chloroplast signal recognition particle delivers LHCPs to the thylakoid membrane by interaction of cpSRP43 with the Alb3 insertase. Here the authors decipher the specific recognition of the Alb3 C-terminal tail within the interface of two communicating chromodomains by structural biochemistry.
- Annemarie Horn
- , Janosch Hennig
- & Irmgard Sinning
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IM30 triggers membrane fusion in cyanobacteria and chloroplasts
Thylakoid membranes are critical components of chloroplasts and cyanobacteria. Here, Hennig et al. demonstrate that IM30, a conserved chloroplast and cyanobacterial protein, binds to thylakoid membranes and can trigger membrane destabilization and fusion in a Mg2+dependent manner.
- Raoul Hennig
- , Jennifer Heidrich
- & Dirk Schneider
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Cytosolic targeting factor AKR2A captures chloroplast outer membrane-localized client proteins at the ribosome during translation
Post-translational import of nuclear-encoded proteins shapes the proteome of organelles. Here, Kim et al.show that AKR2A, a critical targeting factor for chloroplast outer membrane proteins, binds to client proteins co-translationally as they exit the ribosome.
- Dae Heon Kim
- , Jae-Eun Lee
- & Inhwan Hwang
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| Open AccessAtPHT4;4 is a chloroplast-localized ascorbate transporter in Arabidopsis
In plants, ascorbate is synthesized in the mitochondria yet plays essential roles as an antioxidant in the chloroplast. Here, Miyaji et al.show that AtPHT4;4 is a chloroplast envelope ascorbate transporter and suggest it is required for dissipation of excess energy under light stress.
- Takaaki Miyaji
- , Takashi Kuromori
- & Yoshinori Moriyama
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Chloroplast-mediated activation of plant immune signalling in Arabidopsis
Mediators of plant immunity, such as salicylic acid, are produced in the chloroplasts, but the molecular link between chloroplasts and the immune system is unclear. This work finds that pathogen-associated molecular pattern signals are relayed to chloroplasts and evoke Ca2+signatures in the stroma.
- Hironari Nomura
- , Teiko Komori
- & Takashi Shiina
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A chloroplast envelope-bound PHD transcription factor mediates chloroplast signals to the nucleus
Retrograde chloroplast signals are essential in coordinating nuclear gene expression, but the mechanism that relays chloroplast signals to the nucleus remains elusive. In this study, a chloroplast envelope-bound transcription factor PTM is shown to transmit chloroplast signals to the nucleus.
- Xuwu Sun
- , Peiqiang Feng
- & Lixin Zhang
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LTD is a protein required for sorting light-harvesting chlorophyll-binding proteins to the chloroplast SRP pathway
Chloroplast proteins are synthesized in the cytosol and imported into the chloroplast before being delivered to the thylakoids. The authors report that an ankyrin-repeat protein, LTD, is essential for the routing of chlorophyll-binding proteins to the signal recognition particle pathway.
- Min Ouyang
- , Xiaoyi Li
- & Lixin Zhang