GTP-binding proteins in plants

Bischoff, F. Ralf; Molendijk, Arthur J.; Rajendrakumar, C. S. V.; Palme, Klaus

doi:10.1007/s000180050287

Cited by 90 publications

(88 citation statements)

References 271 publications

(263 reference statements)

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“…On the basis of these observations, we suggest that the trafficking defect associated with AtRab1b(N121I) is specific to a trafficking function in which AtRab1b can act. Consistent with this interpretation, the inhibition of secGFP transport by AtRab1b(N121I) was not rescued by coexpression with AtRab8c, a member of a different but closely related Rab subclass, Rab8 Bischoff et al, 1999), which is predicted to perform a different trafficking function from that of AtRAB1b ( Figure 5C). …”

supporting

confidence: 55%

“…In the absence of effective in vivo trafficking assays, information on plant Rab GTPase function has been derived from complementation and expression studies in yeast (Palme et al, 1992;Bednarek et al, 1994;Ueda et al, 2000), immunolocalization data (Ueda et al, 1996), and expression studies (Terryn et al, 1993;Nagano et al, 1995;Moore et al, 1997). Transgenic approaches suggest that disrupting Rab function produces various developmental and cellular anomalies, but they have not identified the in vivo trafficking roles of any plant Rab GTPase (Cheon et al, 1993;Bischoff et al, 1999).A GFP fusion translocated into the lumen of the ER reportedly fails to accumulate in a fluorescent form unless its transport to a post-Golgi compartment is prevented (Boevink et al, 1996(Boevink et al, , 1999. This has been achieved both by providing the GFP with targeting information that causes it to accumulate in either the ER or Golgi apparatus and by treating the cells with brefeldin A (BFA) (Boevink et al, 1996(Boevink et al, , 1999Nebenführ et al, 1999).…”

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confidence: 99%

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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

et al. 2000

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We describe a green fluorescent protein (GFP)-based assay for investigating membrane traffic on the secretory pathway in plants. Expression of At Rab1b(N121I), predicted to be a dominant inhibitory mutant of the Arabidopsis Rab GTPase At Rab1b, resulted in accumulation of a secreted GFP marker in an intracellular reticulate compartment reminiscent of the endoplasmic reticulum. This accumulation was alleviated by coexpressing wild-type At Rab1b but not At Rab8c. When a Golgi-targeted and N -glycosylated variant of GFP was coexpressed with At Rab1b(N121I), the variant also accumulated in a reticulate network and an endoglycosidase H-sensitive population appeared. Unexpectedly, expression of At Rab1b(N121I), but not of the wild-type At Rab1b, resulted in a reduction or cessation of vectorial Golgi movement, an effect that was reversed by coexpression of the wild type. We conclude that At Rab1b function is required for transport from the endoplasmic reticulum to the Golgi apparatus and suggest that this process may be coupled to the control of Golgi movement. INTRODUCTIONThe structure and biosynthetic activities of the endoplasmic reticulum (ER) and Golgi apparatus in higher plants are well described, but the mechanisms that promote and regulate membrane traffic between these compartments are not well understood (reviewed in Robinson and Kristen, 1982;Staehelin and Moore, 1995;Dupree and Sherrier, 1998;Vitale and Denecke, 1999). The Golgi apparatus in higher plants exists as a large number of independent Golgi stacks distributed throughout the cytoplasm. Each Golgi stack typically comprises five to eight flattened cisternae, whose protein and polysaccharide composition may vary in a cis to trans direction across the stack (Zhang and Staehelin, 1992; Wee et al., 1998;Nebenführ et al., 1999). Analysis of tobacco cells in which the Golgi stacks were labeled with green fluorescent protein (GFP) revealed that each stack can travel as much as 2 to 4 m sec Ϫ 1 on an actin network that is coextensive with the dynamic ER network (Boevink et al., 1998;Nebenführ et al., 1999). Consequently, despite the dynamic organization of both the ER and Golgi, both organelles remain in close association. The movement of individual Golgi stacks appears to alternate between two modes: a directed vectorial mode, probably dependent on myosin motors, and a nonvectorial mode involving apparently random oscillations reminiscent of Brownian motion at particular points in the cytoplasm (Nebenführ et al., 1999). Video microscopy of GFP-labeled Golgi stacks in cultured tobacco cells suggests that the control of Golgi movement is devolved to the individual stacks because adjacent stacks can enter independently into phases of vectorial movement, and a stack undergoing vectorial movement can travel past another that is exhibiting the nondirected oscillatory type of motion (Nebenführ et al., 1999).In contrast, the mammalian Golgi apparatus in general forms a single interconnected cluster of membranes at the microtubule organizing center. ER-derived COP...

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confidence: 55%

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confidence: 99%

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

et al. 2000

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“…Overexpression of GCR1 resulted in more GTP␥ 35 S binding, suggesting more active GCR1 coupled to G␣ at the plasma membrane. Binding of GTP␥ 35 S to the membranes of the gpa1-2 mutant was less than in wt, suggesting that total binding in wt membranes reflects binding to GPA1 (a G␣ protein), but possibly also to other G␣ proteins (8) or to small G proteins (31). Overexpression of GCR1 in gpa1 could be used to demonstrate whether GPA1 is coupled to GCR1.…”

Section: Overexpression Of Gcr1 In a Thaliana Abolishes Seed Dormancymentioning

confidence: 99%

GCR1 , the putative Arabidopsis G protein-coupled receptor gene is cell cycle-regulated, and its overexpression abolishes seed dormancy and shortens time to flowering

Colucci

Apone

Alyeshmerni

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

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Although signaling through heterotrimeric G proteins has been extensively studied in eukaryotes, there is little information about this important signaling pathway in plants. We observed that expression of GCR1, the gene encoding the only known (but still putative) G protein-coupled receptor of Arabidopsis thaliana, is modulated during the cell cycle and during plant development. Overexpression of GCR1 in tobacco (Nicotiana tabacum) BY-2 cells caused an increase in thymidine incorporation and in the mitotic index of aphidicolin synchronized cells. Overexpression of GCR1 in Arabidopsis caused two remarkable phenotypes: seed dormancy was abolished and time to flowering was reduced. Molecular markers of these two developmental processes (phosphatase PP2A and MYB65 in germination; LFY during flowering) were upregulated in GCR1 overexpressors. These data are consistent with the hypothesis that GCR1 may be a regulator of the cell cycle and that this regulation underlies the developmental changes observed in the GCR1 transformants.

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“…5) As well as in mammalian cells, this protein complex has been shown to participate in a variety of cellular processes of plants, such as blue or red light-mediated responses, 6) plant hormone signaling, 7) and pathogen-induced resistance mechanisms. 8) It is well known that a-subunits of G-protein complex in mammalian cells are generally composed of more than 20 isoforms 9,10) ; however, in contrast, it has been demonstrated that Ga proteins in plants are usually encoded by only one or two genes in the genomes. [11][12][13][14][15] We showed previously 16) that the biosynthetic activity of a series of tetracyclic diterpenoids, such as scopadulcic acid, scopadulciol, and scopadulin, in Scoparia dulcis is markedly increased when the plant was treated with MJ.…”

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confidence: 99%

Cloning and Characterization of Sdga Gene Encoding .ALPHA.-Subunit of Heterotrimeric Guanosine 5'-Triphosphate-Binding Protein Complex in Scoparia dulcis

Shite

Yamamura

Hayashi

et al. 2008

Biological & Pharmaceutical Bulletin

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A homology-based cloning strategy yielded Sdga, a cDNA clone presumably encoding a a-subunit of heterotrimeric guanosine 5Ј-triphosphate-binding protein complex, from leaf tissues of Scoparia dulcis. Phylogenetic tree analysis of G-protein a a-subunits from various biological sources suggested that, unlike in animal cells, classification of Ga a-proteins into specific subfamilies could not be applicable to the proteins from higher plants. Restriction digests of genomic DNA of S. dulcis showed a single hybridized signal in Southern blot analysis, suggesting that Sdga is a sole gene encoding Ga a-subunit in this plant. The expression level of Sdga appeared to be maintained at almost constant level after exposure of the leaves to methyl jasmonate as analyzed by reverse-transcription polymerase chain reaction. These results suggest that Sdga plays roles in methyl jasmonate-induced responses of S. dulcis without a notable change in the transcriptional level.Key words a-subunit; guanosine 5Ј-triphosphate-binding protein; heterotrimer complex; Scoparia dulcis Biol. Pharm. Bull. 31(11) 2150-2153 (2008) © 2008 Pharmaceutical Society of Japan * To whom correspondence should be addressed. e-mail: kurosaki@pha.u-toyama.ac.jp (G-Biosciences) according to the instruction manuals, and the restriction digests were prepared using XbaI, XhoI, EcoRI, or EcoRV (Takara). They were electrophoresed on a 0.8% agarose gel, and the separated DNA fragments were transferred onto an Immobilon-NY ϩ (Millipore). The translatable region of Sdga including stop codon (1152 nucleotides) was amplified by PCR and was directly labeled with AlkPhos Direct Labeling and Detection System (GE Healthcare Bio-Science) to be used as the probe. The membrane was hybridized with the probe at 55°C for 24 h in a solution containing 6ϫSSC, and, after appropriate washings, the filters were dried and exposed to an X-ray film at room temperature for 3 h. Expression of Sdga GeneThe expression level of Sdga was analyzed semi-quantitatively using RT-PCR. The leaves of S. dulcis were detached from the middle part of the stem, and incubated with MJ (100 mmol l Ϫ1 water, Wako Pure Chemicals) in Petri dishes at 26°C under constant illumination according to the method described previously. 20) Control treatments received only water instead of MJ. At regular intervals, the treated leaves were harvested and total RNA was isolated according to the method described above. Aliquots of RNA solutions (approximately 0.5 mg RNA equivalent) were subjected to RT reaction using Transcriptor First Strand cDNA Synthesis Kit (Roche), and then, PCR was carried out with the primer pair, 5Ј-ATG CGG TGG ATG CTA ATC November 2008 2151 Fig. 1. Alignment of Amino Acids Sequences of a-Subunits of GTP-Binding Protein Complex from Various Biological SourcesA cDNA clone encoding the a-subunit of GTP-binding protein, Sdga, was isolated from S. dulcis, and the deduced amino acid sequence was compared with the proteins from various biological sources (Arab, Arabidopsis thaliana; Rice, Oryza sativa...

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GTP-binding proteins in plants

Cited by 90 publications

References 271 publications

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

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

GCR1 , the putative Arabidopsis G protein-coupled receptor gene is cell cycle-regulated, and its overexpression abolishes seed dormancy and shortens time to flowering

Cloning and Characterization of Sdga Gene Encoding .ALPHA.-Subunit of Heterotrimeric Guanosine 5'-Triphosphate-Binding Protein Complex in Scoparia dulcis

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