A Rab1 GTPase Is Required for Transport between the Endoplasmic Reticulum and Golgi Apparatus and for Normal Golgi Movement in Plants

Batoko, Henri; Zheng, Huanquan; Hawes, Chris; Moore, Ian D.

doi:10.2307/3871115

Cited by 253 publications

(459 citation statements)

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“…In an optical section at the level of the cortex cytoplasm, the fluorescence appeared as a reticulate polygonal network often linked with punctuated structures (Figure 10E). Based on published data, this distinct pattern can be identified as indicating localization to the ER (Boevink et al, 1996(Boevink et al, , 1998Batoko et al, 2000). The ER localization of AtCKX2-GFP was supported further by the visualization of motile, spindle-shaped fluorescent bodies in the epidermis of petioles ( Figure 10F).…”

Section: Atckx Proteins Have Different Subcellular Localizationsmentioning

confidence: 78%

“…This was indicated previously by its excretion from yeast cells (Werner et al, 2001). Our inability to detect the GFP signal in the apoplast could be explained by the weak fluorescence of secreted GFP (Batoko et al, 2000). Interestingly, an increase in the extracellular CKX fraction was triggered in tobacco cell cultures by cytokinin and was correlated with enhanced CKX glycosylation (Motyka et al, 2003).…”

Section: Differential Subcellular Targeting Of Atckx Proteinsmentioning

confidence: 87%

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Cytokinin-Deficient Transgenic Arabidopsis Plants Show Multiple Developmental Alterations Indicating Opposite Functions of Cytokinins in the Regulation of Shoot and Root Meristem Activity

Werner

Motyka

Laucou³

et al. 2003

Plant Cell

1,322

1,243

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Cytokinins are hormones that regulate cell division and development. As a result of a lack of specific mutants and biochemical tools, it has not been possible to study the consequences of cytokinin deficiency. Cytokinin-deficient plants are expected to yield information about processes in which cytokinins are limiting and that, therefore, they might regulate. We have engineered transgenic Arabidopsis plants that overexpress individually six different members of the cytokinin oxidase/dehydrogenase ( AtCKX ) gene family and have undertaken a detailed phenotypic analysis. Transgenic plants had increased cytokinin breakdown (30 to 45% of wild-type cytokinin content) and reduced expression of the cytokinin reporter gene ARR5 : GUS ( ␤ -glucuronidase). Cytokinin deficiency resulted in diminished activity of the vegetative and floral shoot apical meristems and leaf primordia, indicating an absolute requirement for the hormone. By contrast, cytokinins are negative regulators of root growth and lateral root formation. We show that the increased growth of the primary root is linked to an enhanced meristematic cell number, suggesting that cytokinins control the exit of cells from the root meristem. Different AtCKX-green fluorescent protein fusion proteins were localized to the vacuoles or the endoplasmic reticulum and possibly to the extracellular space, indicating that subcellular compartmentation plays an important role in cytokinin biology. Analyses of promoter: GUS fusion genes showed differential expression of AtCKX genes during plant development, the activity being confined predominantly to zones of active growth. Our results are consistent with the hypothesis that cytokinins have central, but opposite, regulatory functions in root and shoot meristems and indicate that a fine-tuned control of catabolism plays an important role in ensuring the proper regulation of cytokinin functions.

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Section: Atckx Proteins Have Different Subcellular Localizationsmentioning

confidence: 78%

Section: Differential Subcellular Targeting Of Atckx Proteinsmentioning

confidence: 87%

Cytokinin-Deficient Transgenic Arabidopsis Plants Show Multiple Developmental Alterations Indicating Opposite Functions of Cytokinins in the Regulation of Shoot and Root Meristem Activity

Werner

Motyka

Laucou³

et al. 2003

Plant Cell

1,322

1,243

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“…In addition to this, the ␣-amylase transport assays can now be used for the functional analysis of Sec12p using the inhibition assay or for the analysis of Sar1p in the rescue assay. This should prove valuable as an additional tool in combination with the use of GTPase mutants that exhibit a trans dominant negative effect on secretion (Batoko et al, 2000;Takeuchi et al, 2000) (Figure 5). …”

Section: Sec12p Overexpression Inhibits Copii Transport Through the Dmentioning

confidence: 99%

Secretory Bulk Flow of Soluble Proteins Is Efficient and COPII Dependent

Phillipson¹,

Pimpl²,

daSilva³

et al. 2001

The Plant Cell

159

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COPII-coated vesicles, first identified in yeast and later characterized in mammalian cells, mediate protein export from the endoplasmic reticulum (ER) to the Golgi apparatus within the secretory pathway. In these organisms, the mechanism of vesicle formation is well understood, but the process of soluble cargo sorting has yet to be resolved. In plants, functional complements of the COPII-dependent protein traffic machinery were identified almost a decade ago, but the selectivity of the ER export process has been subject to considerable debate. To study the selectivity of COPII-dependent protein traffic in plants, we have developed an in vivo assay in which COPII vesicle transport is disrupted at two distinct steps in the pathway. First, overexpression of the Sar1p-specific guanosine nucleotide exchange factor Sec12p was shown to result in the titration of the GTPase Sar1p, which is essential for COPII-coated vesicle formation. A second method to disrupt COPII transport at a later step in the pathway was based on coexpression of a dominant negative mutant of Sar1p (H74L), which is thought to interfere with the uncoating and subsequent membrane fusion of the vesicles because of the lack of GTPase activity. A quantitative assay to measure ER export under these conditions was achieved using the natural secretory protein barley ␣ -amylase and a modified version carrying an ER retention motif. Most importantly, the manipulation of COPII transport in vivo using either of the two approaches allowed us to demonstrate that export of the ER resident protein calreticulin or the bulk flow marker phosphinothricin acetyl transferase is COPII dependent and occurs at a much higher rate than estimated previously. We also show that the instability of these proteins in post-ER compartments prevents the detection of the true rate of bulk flow using a standard secretion assay. The differences between the data on COPII transport obtained from these in vivo experiments and in vitro experiments conducted previously using yeast components are discussed. INTRODUCTIONIn yeast and mammalian cells, the export of proteins from the endoplasmic reticulum (ER) occurs in COPII-coated vesicles. The process of COPII vesicle formation is well understood and can be reconstituted using purified yeast components (Barlowe et al., 1994). Vesicle formation in vitro depends solely on the ER donor membrane, the GTPase Sar1p, the Sar1p-specific guanosine nucleotide exchange factor Sec12p, the cytosolic COPII coat components, and GTP (Barlowe et al., 1994). Considerably less is known about the sorting of soluble cargo molecules during ER export in eukaryotes (Klumperman, 2000), and conflicting reports from the plant field have contributed to the ongoing discussions (Crofts et al., 1999;Gomord and Faye, 2000;Pagny et al., 2000;.To support protein synthesis and folding, the ER lumen maintains high levels of soluble residents such as the lumenal binding protein (BiP), protein disulfide isomerase, or calreticulin. The concentration of nonresidents in the ER lume...

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“…Transient expression of YFP-and GFP-tagged constructs in tobacco (Nicotiana tabacum 'Petit Havana') was performed as described previously (Batoko et al, 2000). Briefly, 3-mL overnight cultures of recombinant A. tumefaciens (strain GV3101) grown at 28°C in YEB medium (per liter: 5 g of beef extract, 1 g of yeast extract, 5 g of Suc, and 0.5 g of MgSO 4 -7H 2 O, supplemented with 50 mg mL 21 kanamycin and 10 mg mL 21 rifampicin) were harvested by centrifugation at 4,000g for 5 min, and the pellet was washed and resuspended to an optical density at 600 nm of 0.05 in induction medium (50 mM MES, pH 5.6, 2 mM NaH 2 PO 4 , 0.05% [w/v] Glc, and 200 mM acetosyringone).…”

Section: Transient Expression In Tobaccomentioning

confidence: 99%

Differential Control of Ethylene Responses byGREEN-RIPEandGREEN-RIPE LIKE1Provides Evidence for Distinct Ethylene Signaling Modules in Tomato

Brandizzí

et al. 2012

Plant Physiology

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The factors that mediate specific responses to the plant hormone ethylene are not fully defined. In particular, it is not known how signaling at the receptor complex can control distinct subsets of ethylene responses. Mutations at the Green-ripe (Gr) and reversion to ethylene sensitivity1 (rte1) loci, which encode homologous proteins of unknown function, influence ethylene responses in tomato (Solanum lycopersicum) and Arabidopsis (Arabidopsis thaliana), respectively. In Arabidopsis, AtRTE1 is required for function of the ETR1 ethylene receptor and acts predominantly through this receptor via direct protein-protein interaction. While most eudicot families including the Brassicaceae possess a single gene that is closely related to AtRTE1, we report that members of the Solanaceae family contain two phylogenetically distinct genes defined by GR and GREEN-RIPE LIKE1 (GRL1), creating the possibility of subfunctionalization. We also show that SlGR and SlGRL1 are differentially expressed in tomato tissues and encode proteins predominantly localized to the Golgi. A combination of overexpression in tomato and complementation of the rte1-3 mutant allele indicates that SlGR and SlGRL1 influence distinct but overlapping ethylene responses. Overexpression of SlGRL1 in the Gr mutant background provides evidence for the existence of different ethylene signaling modules in tomato that are influenced by GR, GRL1, or both. In addition, overexpression of AtRTE1 in tomato leads to reduced ethylene responsiveness in a subset of tissues but does not mimic the Gr mutant phenotype. Together, these data reveal species-specific heterogeneity in the control of ethylene responses mediated by members of the GR/RTE1 family.The gaseous plant hormone ethylene influences many aspects of plant development and mediates responses to biotic and abiotic stresses (Abeles et al., 1992). Impaired ethylene biosynthesis and responsiveness can lead to altered cell expansion, cell elongation, senescence, abscission, cell death, fruit ripening, root hair formation, lateral root development, nodulation, and sex determination (Bleecker et al

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A Rab1 GTPase Is Required for Transport between the Endoplasmic Reticulum and Golgi Apparatus and for Normal Golgi Movement in Plants

Cited by 253 publications

References 0 publications

Cytokinin-Deficient Transgenic Arabidopsis Plants Show Multiple Developmental Alterations Indicating Opposite Functions of Cytokinins in the Regulation of Shoot and Root Meristem Activity

Cytokinin-Deficient Transgenic Arabidopsis Plants Show Multiple Developmental Alterations Indicating Opposite Functions of Cytokinins in the Regulation of Shoot and Root Meristem Activity

Secretory Bulk Flow of Soluble Proteins Is Efficient and COPII Dependent

Differential Control of Ethylene Responses byGREEN-RIPEandGREEN-RIPE LIKE1Provides Evidence for Distinct Ethylene Signaling Modules in Tomato

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