The exocyst complex in plants

Eliáš, Marek; Drdová, Edita Janková; Ziak, D.; Bavlnka, B.; Hála, Michal; Cvrčková, Fatima; Soukupová, Hana; Žárský, Viktor

doi:10.1016/s1065-6995(02)00349-9

Cited by 123 publications

(120 citation statements)

References 6 publications

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“…Indeed, considerable data have accumulated over the last 5 years that confirm the existence of the exocyst in plants and its importance for polarized plant growth (Zá rský et al, 2009). Not only has in silico research resulted in the identification of homologs of all exocyst subunits (Elias et al, 2003;Synek et al, 2006;Chong et al, 2010), but a 900-kD complex containing seven of the eight exocyst subunits has recently been successfully identified from an Arabidopsis cell extract (Há la et al, 2008). Moreover, a number of studies have described the deleterious effects on growth, especially localized tip growth in pollen tubes and root hairs in plants expressing mutant exocyst proteins (Cole et al, 2005;Wen et al, 2005;Synek et al, 2006;Há la et al, 2008;Samuel et al, 2009).…”

Section: Exocyst and Expomentioning

confidence: 99%

“…Homologs to all eight exocyst proteins have been found in plants (Elias et al, 2003;Chong et al, 2010;Há la et al, 2008), but interestingly, there are over 23 paralogs of Exo70 in Arabidopsis thaliana, with Exo70A1 being the most abundant (Synek et al, 2006). It has recently been proposed by Zá rský et al (2009) that the large number of Exo70 proteins, together with the greater number of SNAREs and Rab GTPases (Rutherford and Moore, 2002;Lipka et al, 2007), reflect an increased variability in targeting domains for vesicle traffic in plant cells.…”

Section: Introductionmentioning

confidence: 99%

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EXPO, an Exocyst-Positive Organelle Distinct from Multivesicular Endosomes and Autophagosomes, Mediates Cytosol to Cell Wall Exocytosis inArabidopsisand Tobacco Cells

et al. 2010

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The exocyst protein complex mediates vesicle fusion with the plasma membrane. By expressing an (X)FP-tagged Arabidopsis thaliana homolog of the exocyst protein Exo70 in suspension-cultured Arabidopsis and tobacco (Nicotiana tabacum) BY-2 cells, and using antibodies specific for Exo70, we detected a compartment, which we term EXPO (for exocyst positive organelles). Standard markers for the Golgi apparatus, the trans-Golgi network/early endosome, and the multivesicular body/ late endosome in plants do not colocalize with EXPO. Inhibitors of the secretory and endocytic pathways also do not affect EXPO. Exo70E2-(X)FP also locates to the plasma membrane (PM) as discrete punctae and is secreted outside of the cells. Immunogold labeling of sections cut from high-pressure frozen samples reveal EXPO to be spherical double membrane structures resembling autophagosomes. However, unlike autophagosomes, EXPOs are not induced by starvation and do not fuse with the lytic compartment or with endosomes. Instead, they fuse with the PM, releasing a single membrane vesicle into the cell wall. EXPOs are also found in other cell types, including root tips, root hair cells, and pollen grains. EXPOs therefore represent a form of unconventional secretion unique to plants.

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Section: Exocyst and Expomentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

EXPO, an Exocyst-Positive Organelle Distinct from Multivesicular Endosomes and Autophagosomes, Mediates Cytosol to Cell Wall Exocytosis inArabidopsisand Tobacco Cells

et al. 2010

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“…Most metazoans possess only one Exo70 gene. By contrast, the Exo70 gene family underwent a substantial expansion unique to plants (Elias et al, 2003;Synek et al, 2006;Chong et al, 2010). In Arabidopsis, 23 homologs can be found ( Figure 1A), and rice (Oryza sativa) contains at least 32 (Cvr cková et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

The Ubiquitin Ligase PUB22 Targets a Subunit of the Exocyst Complex Required for PAMP-Triggered Responses in Arabidopsis

et al. 2012

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Plant pathogens are perceived by pattern recognition receptors, which are activated upon binding to pathogen-associated molecular patterns (PAMPs). Ubiquitination and vesicle trafficking have been linked to the regulation of immune signaling. However, little information exists about components of vesicle trafficking involved in immune signaling and the mechanisms that regulate them. In this study, we identified Arabidopsis thaliana Exo70B2, a subunit of the exocyst complex that mediates vesicle tethering during exocytosis, as a target of the plant U-box-type ubiquitin ligase 22 (PUB22), which acts in concert with PUB23 and PUB24 as a negative regulator of PAMP-triggered responses. We show that Exo70B2 is required for both immediate and later responses triggered by all tested PAMPs, suggestive of a role in signaling. Exo70B2 is also necessary for the immune response against different pathogens. Our data demonstrate that PUB22 mediates the ubiquitination and degradation of Exo70B2 via the 26S Proteasome. Furthermore, degradation is regulated by the autocatalytic turnover of PUB22, which is stabilized upon PAMP perception. We therefore propose a mechanism by which PUB22-mediated degradation of Exo70B2 contributes to the attenuation of PAMP-induced signaling.

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“…Exocyst is an evolutionarily conserved protein complex in all eukaryotes and plays an important role in polarized exocytosis (Elias et al, 2003;Munson and Novick, 2006;Cvr cková et al, 2012). The exocyst complex consists of eight subunits (SEC3, SEC5, SEC6, SEC8, SEC10, SEC15, EXO70, and EXO84).…”

mentioning

confidence: 99%

“…The exocyst complex consists of eight subunits (SEC3, SEC5, SEC6, SEC8, SEC10, SEC15, EXO70, and EXO84). Although it has been initially described in yeast (Saccharomyces cerevisiae; TerBush et al, 1996), homologs of all of the subunits have been described in plants (Elias et al, 2003), where they also form a complex (Hála et al, 2008). The role of the exocyst complex is tethering and docking of the post-Golgi vesicles to plasma membrane.…”

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confidence: 99%

Cell Wall Maturation of Arabidopsis Trichomes Is Dependent on Exocyst Subunit EXO70H4 and Involves Callose Deposition

et al. 2015

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Arabidopsis (Arabidopsis thaliana) leaf trichomes are single-cell structures with a well-studied development, but little is understood about their function. Developmental studies focused mainly on the early shaping stages, and little attention has been paid to the maturation stage. We focused on the EXO70H4 exocyst subunit, one of the most up-regulated genes in the mature trichome. We uncovered EXO70H4-dependent development of the secondary cell wall layer, highly autofluorescent and callose rich, deposited only in the upper part of the trichome. The boundary is formed between the apical and the basal parts of mature trichome by a callose ring that is also deposited in an EXO70H4-dependent manner. We call this structure the Ortmannian ring (OR). Both the secondary cell wall layer and the OR are absent in the exo70H4 mutants. Ecophysiological aspects of the trichome cell wall thickening include interference with antiherbivore defense and heavy metal accumulation. Ultraviolet B light induces EXO70H4 transcription in a CONSTITUTIVE PHOTOMORPHOGENIC1-dependent way, resulting in stimulation of trichome cell wall thickening and the OR biogenesis. EXO70H4-dependent trichome cell wall hardening is a unique phenomenon, which may be conserved among a variety of the land plants. Our analyses support a concept that Arabidopsis trichome is an excellent model to study molecular mechanisms of secondary cell wall deposition.

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The exocyst complex in plants

Cited by 123 publications

References 6 publications

EXPO, an Exocyst-Positive Organelle Distinct from Multivesicular Endosomes and Autophagosomes, Mediates Cytosol to Cell Wall Exocytosis inArabidopsisand Tobacco Cells

EXPO, an Exocyst-Positive Organelle Distinct from Multivesicular Endosomes and Autophagosomes, Mediates Cytosol to Cell Wall Exocytosis inArabidopsisand Tobacco Cells

The Ubiquitin Ligase PUB22 Targets a Subunit of the Exocyst Complex Required for PAMP-Triggered Responses in Arabidopsis

Cell Wall Maturation of Arabidopsis Trichomes Is Dependent on Exocyst Subunit EXO70H4 and Involves Callose Deposition

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