Underlying data for: The Arabidopsis thaliana TRAPPIII subunit AtTRAPPC8/AtTRS85 is involved in ER functions and autophagy
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ABSTRACT:
ORGANISM(S): Arabidopsis thaliana (thale cress)
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PROVIDER: S-BSST1721 | biostudies-other |
REPOSITORIES: biostudies-other
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Project description:The endoplasmic reticulum (ER) is the major site for protein folding in eukaryotic cells. ER homeostasis is essential for the development of an organism, whereby the unfolded protein response (UPR) within the ER is precisely regulated. ER-phagy is a newly identified selective autophagic pathway for removal of misfolded or unfolded proteins within the ER in mammalian cells. Sec62, a component of the translocon complex, was recently characterized as an ER-phagy receptor during the ER stress recovery phase in mammals. In this study, we demonstrated that the Arabidopsis Sec62 (AtSec62) is required for plant development and might function as an ER-phagy receptor in plants. We showed that AtSec62 is an ER-localized membrane protein with three transmembrane domains (TMDs) with its C-terminus facing to the ER lumen. AtSec62 is required for plant development because atsec62 mutants display impaired vegetative growth, abnormal pollen and decreased fertility. atsec62 mutants are sensitive towards tunicamycin (TM)-induced ER stress, whereas overexpression of AtSec62 subsequently enhances stress tolerance during the ER stress recovery phase. Moreover, YFP-AtSec62 colocalizes with the autophagosome marker mCh-Atg8e in ring-like structures upon ER stress induction. Taken together, these data provide evidence for the pivotal roles of AtSec62 in plant development and ER-phagy.
| S-EPMC7028082 | biostudies-literature
Project description:The receptor kinase FERONIA (FER) is a versatile regulator of plant growth and development, biotic and abiotic stress responses, and reproduction. To gain new insights into the molecular interplay of these processes and to identify new FER functions, we carried out quantitative transcriptome, proteome, and phosphoproteome profiling of Arabidopsis (Arabidopsis thaliana) wild-type and fer-4 loss-of-function mutant plants. Gene ontology terms for phytohormone signaling, abiotic stress, and biotic stress were significantly enriched among differentially expressed transcripts, differentially abundant proteins, and/or misphosphorylated proteins, in agreement with the known roles for FER in these processes. Analysis of multiomics data and subsequent experimental evidence revealed previously unknown functions for FER in endoplasmic reticulum (ER) body formation and glucosinolate biosynthesis. FER functions through the transcription factor NAI1 to mediate ER body formation. FER also negatively regulates indole glucosinolate biosynthesis, partially through NAI1. Furthermore, we found that a group of abscisic acid (ABA)-induced transcription factors is hypophosphorylated in the fer-4 mutant and demonstrated that FER acts through the transcription factor ABA INSENSITIVE5 (ABI5) to negatively regulate the ABA response during cotyledon greening. Our integrated omics study, therefore, reveals novel functions for FER and provides new insights into the underlying mechanisms of FER function.
| S-EPMC9252503 | biostudies-literature
Project description:Macroautophagy/autophagy is a conserved process in eukaryotes that contributes to cell survival in response to stress. Previously, we found that endoplasmic reticulum (ER) stress induces autophagy in plants via a pathway dependent upon AT5G24360/IRE1B (INOSITOL REQUIRING 1-1), an ER membrane-anchored factor involved in the splicing of AT1G42990/BZIP60 (basic leucine zipper protein 60) mRNA. IRE1B is a dual protein kinase and ribonuclease, and here we determined the involvement of the protein kinase catalytic domain, nucleotide binding and RNase domains of IRE1B in activating autophagy. We found that the nucleotide binding and RNase activity of IRE1B, but not its protein kinase activity or splicing target BZIP60, are required for ER stress-mediated autophagy. Upon ER stress, the RNase activity of IRE1B engages in regulated IRE1-dependent decay of messenger RNA (RIDD), in which mRNAs of secreted proteins are degraded by IRE1 upon ER stress. Twelve genes most highly targeted by RIDD were tested for their role in inhibiting ER stress-induced autophagy, and 3 of their encoded proteins, AT1G66270/BGLU21 (?-glucosidase 21), AT2G16005/ROSY1/ML (MD2-related lipid recognition protein) and AT5G01870/PR-14 (pathogenesis-related protein 14), were found to inhibit autophagy upon overexpression. From these findings, IRE1B is posited to be a 'licensing factor' linking ER stress to autophagy by degrading the RNA transcripts of factors that interfere with the induction of autophagy. ABBREVIATIONS:ACT2: actin 2; ATG: autophagy-related; BGLU21: ?-glucosidase 21; BIP3: binding protein 3; BZIP: basic leucine zipper; DAPI: 4', 6-diamidino-2-phenylindole; DTT: dithiothreitol; ER: endoplasmic reticulum; ERN1: endoplasmic reticulum to nucleus signaling 1; IRE1: inositol requiring 1; GFP: green fluorescent protein; MAP3K5/ASK1: mitogen-activated protein kinase kinase kinase 5; MAPK8/JNK1: mitogen-activated protein kinase 8/c-Jun N-terminal kinase 1; MDC: monodansylcadaverine; PR-14: pathogenesis-related protein 14; RIDD: Regulated IRE1-Dependent Decay of Messenger RNA; ROSY1/ML: interactor of synaptotagmin1/MD2-related lipid recognition protein; Tm: tunicamycin; UPR: unfolded protein response; WT: wild-type.
| S-EPMC6135571 | biostudies-literature
Project description:The endoplasmic reticulum (ER) has a unique, network-like morphology. The ER structures are composed of tubules, cisternae, and three-way junctions. This morphology is highly conserved among eukaryotes, but the molecular mechanism that maintains ER morphology has not yet been elucidated. In addition, certain Brassicaceae plants develop a unique ER-derived organelle called the ER body. This organelle accumulates large amounts of PYK10, a ?-glucosidase, but its physiological functions are still obscure. We aimed to identify a novel factor required for maintaining the morphology of the ER, including ER bodies, and employed a forward-genetic approach using transgenic Arabidopsis thaliana (GFP-h) with fluorescently-labeled ER. We isolated and investigated a mutant (designated endoplasmic reticulum morphology3, ermo3) with huge aggregates and abnormal punctate structures of ER. ERMO3 encodes a GDSL-lipase/esterase family protein, also known as MVP1. Here, we showed that, although ERMO3/MVP1/GOLD36 was expressed ubiquitously, the morphological defects of ermo3 were specifically seen in a certain type of cells where ER bodies developed. Coimmunoprecipitation analysis combined with mass spectrometry revealed that ERMO3/MVP1/GOLD36 interacts with the PYK10 complex, a huge protein complex that is thought to be important for ER body-related defense systems. We also found that the depletion of transcription factor NAI1, a master regulator for ER body formation, suppressed the formation of ER-aggregates in ermo3 cells, suggesting that NAI1 expression plays an important role in the abnormal aggregation of ER. Our results suggest that ERMO3/MVP1/GOLD36 is required for preventing ER and other organelles from abnormal aggregation and for maintaining proper ER morphology in a coordinated manner with NAI1.
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Project description:BackgroundDNA topoisomerases are enzymes that control the topology of DNA in all cells. DNA gyrase is unique among the topoisomerases in that it is the only enzyme that can actively supercoil DNA using the free energy of ATP hydrolysis. Until recently gyrase was thought to be unique to bacteria, but has now been discovered in plants. The genome of the model plant, Arabidopsis thaliana, is predicted to encode four gyrase subunits: AtGyrA, AtGyrB1, AtGyrB2 and AtGyrB3.Methodology/principal findingsWe found, contrary to previous data, that AtGyrB3 is not essential to the survival of A. thaliana. Bioinformatic analysis suggests AtGyrB3 is considerably shorter than other gyrase B subunits, lacking part of the ATPase domain and other key motifs found in all type II topoisomerases; but it does contain a putative DNA-binding domain. Partially purified AtGyrB3 cannot bind E. coli GyrA or support supercoiling. AtGyrB3 cannot complement an E. coli gyrB temperature-sensitive strain, whereas AtGyrB2 can. Yeast two-hybrid analysis suggests that AtGyrB3 cannot bind to AtGyrA or form a dimer.Conclusions/significanceThese data strongly suggest that AtGyrB3 is not a gyrase subunit but has another unknown function. One possibility is that it is a nuclear protein with a role in meiosis in pollen.
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Project description:The plant endoplasmic reticulum (ER) is crucial to the maintenance of cellular homeostasis. The ER consists of a dynamic and continuously remodelling network of tubules and cisternae. Several conserved membrane proteins have been implicated in formation and maintenance of the ER network in plants, such as RHD3 and the reticulon proteins. Despite the recent work in mammalian and yeast cells, the detailed molecular mechanisms of ER network organization in plants remain largely unknown. Recently, novel ER network-shaping proteins called Lunapark (LNP) have been identified in yeast and mammalian cells. Here we identify two Arabidopsis LNP homologues and investigate their subcellular localization via confocal microscopy and potential function in shaping the ER network using protein-protein interaction assays and mutant analysis. We show that AtLNP1 overexpression in tobacco leaf epidermal cells mainly labels cisternae in the ER network, whereas AtLNP2 labels the whole ER. Overexpression of LNP proteins results in an increased abundance of ER cisternae and lnp1 and lnp1lnp2 amiRNA lines display a reduction in cisternae and larger polygonal areas. Thus, we hypothesize that AtLNP1 and AtLNP2 are involved in determining the network morphology of the plant ER, possibly by regulating the formation of ER cisternae.
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Project description:Hydrogen sulfide (H2S) is an endogenously generated gaseous signaling molecule, which recently has been implicated in autophagy regulation in both plants and mammals through persulfidation of specific targets. Persulfidation has been suggested as the molecular mechanism through which sulfide regulates autophagy in plant cells. ATG18a is a core autophagy component that is required for bulk autophagy and also for reticulophagy during endoplasmic reticulum (ER) stress. In this research, we revealed the role of sulfide in plant ER stress responses as a negative regulator of autophagy. We demonstrate that sulfide regulates ATG18a phospholipid-binding activity by reversible persulfidation at Cys103, and that this modification activates ATG18a binding capacity to specific phospholipids in a reversible manner. Our findings strongly suggest that persulfidation of ATG18a at C103 regulates autophagy under ER stress, and that the impairment of persulfidation affects both the number and size of autophagosomes.
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Project description:The elongator complex subunit 2 (ELP2) protein, one subunit of an evolutionarily conserved histone acetyltransferase complex, has been shown to participate in leaf patterning, plant immune and abiotic stress responses in Arabidopsis thaliana. Here, its role in root development was explored. Compared to the wild type, the elp2 mutant exhibited an accelerated differentiation of its root stem cells and cell division was more active in its quiescent centre (QC). The key transcription factors responsible for maintaining root stem cell and QC identity, such as AP2 transcription factors PLT1 (PLETHORA1) and PLT2 (PLETHORA2), GRAS transcription factors such as SCR (SCARECROW) and SHR (SHORT ROOT) and WUSCHEL-RELATED HOMEOBOX5 transcription factor WOX5, were all strongly down-regulated in the mutant. On the other hand, expression of the G2/M transition activator CYCB1 was substantially induced in elp2. The auxin efflux transporters PIN1 and PIN2 showed decreased protein levels and PIN1 also displayed mild polarity alterations in elp2, which resulted in a reduced auxin content in the root tip. Either the acetylation or methylation level of each of these genes differed between the mutant and the wild type, suggesting that the ELP2 regulation of root development involves the epigenetic modification of a range of transcription factors and other developmental regulators.
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Project description:Glucosinolates are plant secondary metabolites present in Brassicaceae plants such as the model plant Arabidopsis thaliana. Intact glucosinolates are believed to be biologically inactive, whereas degradation products after hydrolysis have multiple roles in growth regulation and defense. The degradation of glucosinolates is catalyzed by thioglucosidases called myrosinases and leads by default to the formation of isothiocyanates. The interaction of a protein called epithiospecifier protein (ESP) with myrosinase diverts the reaction toward the production of epithionitriles or nitriles depending on the glucosinolate structure. Here we report the identification of a new group of nitrile-specifier proteins (AtNSPs) in A. thaliana able to generate nitriles in conjunction with myrosinase and a more detailed characterization of one member (AtNSP2). Recombinant AtNSP2 expressed in Escherichia coli was used to test its impact on the outcome of glucosinolate hydrolysis using a gas chromatography-mass spectrometry approach. AtNSP proteins share 30-45% sequence homology with A. thaliana ESP. Although AtESP and AtNSP proteins can switch myrosinase-catalyzed degradation of 2-propenylglucosinolate from isothiocyanate to nitrile, only AtESP generates the corresponding epithionitrile. Using the aromatic benzylglucosinolate, recombinant AtNSP2 is also able to direct product formation to the nitrile. Analysis of glucosinolate hydrolysis profiles of transgenic A. thaliana plants overexpressing AtNSP2 confirms its nitrile-specifier activity in planta. In silico expression analysis reveals distinctive expression patterns of AtNSPs, which supports a biological role for these proteins. In conclusion, we show that AtNSPs belonging to a new family of A. thaliana proteins structurally related to AtESP divert product formation from myrosinase-catalyzed glucosinolate hydrolysis and, thereby, likely affect the biological consequences of glucosinolate degradation. We discuss similarities and properties of AtNSPs and related proteins and the biological implications.
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Project description:Plants can defend themselves against a wide array of enemies, from microbes to large animals, yet there is great variability in the effectiveness of such defences, both within and between species. Some of this variation can be explained by conflicting pressures from pathogens with different modes of attack. A second explanation comes from an evolutionary 'tug of war', in which pathogens adapt to evade detection, until the plant has evolved new recognition capabilities for pathogen invasion. If selection is, however, sufficiently strong, susceptible hosts should remain rare. That this is not the case is best explained by costs incurred from constitutive defences in a pest-free environment. Using a combination of forward genetics and genome-wide association analyses, we demonstrate that allelic diversity at a single locus, ACCELERATED CELL DEATH 6 (ACD6), underpins marked pleiotropic differences in both vegetative growth and resistance to microbial infection and herbivory among natural Arabidopsis thaliana strains. A hyperactive ACD6 allele, compared to the reference allele, strongly enhances resistance to a broad range of pathogens from different phyla, but at the same time slows the production of new leaves and greatly reduces the biomass of mature leaves. This allele segregates at intermediate frequency both throughout the worldwide range of A. thaliana and within local populations, consistent with this allele providing substantial fitness benefits despite its marked impact on growth.
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