The Syntaxin Homolog AtPEP12p Resides on a Late Post-Golgi Compartment in Plants

Conceição, Alexandre da Silva; Marty-Mazars, Daniele; Bassham, Diane C.; Sanderfoot, Anton A.; Marty, Francis; Raikhel, Natasha V.

doi:10.2307/3870508

Cited by 48 publications

(38 citation statements)

References 9 publications

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“…It was also found on the PVC membranes where it colocalized with VTI11 and SYP51 (da Silva Conceicao et al, 1997;Sanderfoot et al, 1998Sanderfoot et al, , 2001aZheng et al, 1999;Bassham et al, 2000;Uemura et al, 2004). This corresponds well with the coprecipitation data and supports the view that these three SNAREs are likely to form a SNARE complex involved in Golgi-to-PVC trafficking Sanderfoot et al, 2001a).…”

Section: Introductionsupporting

confidence: 74%

Overexpression of theArabidopsisSyntaxin PEP12/SYP21 Inhibits Transport from the Prevacuolar Compartment to the Lytic Vacuole in Vivo

2006

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Golgi-mediated transport to the lytic vacuole involves passage through the prevacuolar compartment (PVC), but little is known about how vacuolar proteins exit the PVC. We show that this last step is inhibited by overexpression of Arabidopsis thaliana syntaxin PEP12/SYP21, causing an accumulation of soluble and membrane cargo and the plant vacuolar sorting receptor BP80 in the PVC. Anterograde transport proceeds normally from the endoplasmic reticulum to the Golgi and the PVC, although export from the PVC appears to be compromised, affecting both anterograde membrane flow to the vacuole and the recycling route of BP80 to the Golgi. However, Golgi-mediated transport of soluble and membrane cargo toward the plasma membrane is not affected, but a soluble BP80 ligand is partially mis-sorted to the culture medium. We also observe clustering of individual PVC bodies that move together and possibly fuse with each other, forming enlarged compartments. We conclude that PEP12/SYP21 overexpression specifically inhibits export from the PVC without affecting the Golgi complex or compromising the secretory branch of the endomembrane system. The results provide a functional in vivo assay that confirms PEP12/SYP21 involvement in vacuolar sorting and indicates that excess of this syntaxin in the PVC can be detrimental for further transport from this organelle.

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Section: Introductionsupporting

confidence: 74%

Overexpression of theArabidopsisSyntaxin PEP12/SYP21 Inhibits Transport from the Prevacuolar Compartment to the Lytic Vacuole in Vivo

2006

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“…The fractionated sample was enriched for the SYP61 fusion protein, but contained minor traces of the abundant ER marker BiP [20] and the PVC marker SYP21 [21] (Supplementary information, Figure S1). These contaminants were eliminated in the second immunopurification step ( Figure 1A).…”

Section: Resultsmentioning

confidence: 99%

Isolation and proteomic analysis of the SYP61 compartment reveal its role in exocytic trafficking in Arabidopsis

et al. 2011

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The endomembrane system is a complex and dynamic intracellular trafficking network. It is very challenging to track individual vesicles and their cargos in real time; however, affinity purification allows vesicles to be isolated in their natural state so that their constituent proteins can be identified. Pioneering this approach in plants, we isolated the SYP61 trans-Golgi network compartment and carried out a comprehensive proteomic analysis of its contents with only minimal interference from other organelles. The proteome of SYP61 revealed the association of proteins of unknown function that have previously not been ascribed to this compartment. We identified a complete SYP61 SNARE complex, including regulatory proteins and validated the proteome data by showing that several of these proteins associated with SYP61 in planta. We further identified the SYP121-complex and cellulose synthases, suggesting that SYP61 plays a role in the exocytic trafficking and the transport of cell wall components to the plasma membrane. The presence of proteins of unknown function in the SYP61 proteome including ECHIDNA offers the opportunity to identify novel trafficking components and cargos. The affinity purification of plant vesicles in their natural state provides a basis for further analysis and dissection of complex endomembrane networks. The approach is widely applicable and can afford the study of several vesicle populations in plants, which can be compared with the SYP61 vesicle proteome.

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“…Western blotting was carried out using antibodies for TIP [34], PIP [35] and LHCb3 (Agrisera AB, Sweden). Secondary antibodies (anti-rabbit or anti-chicken, coupled to alkaline phosphatase …”

Section: Western Blottingmentioning

confidence: 99%

Quantitative detection of changes in the leaf‐mesophyll tonoplast proteome in dependency of a cadmium exposure of barley (Hordeum vulgare L.) plants

et al. 2009

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Although the vacuole is the most important final store for toxic heavy metals like cadmium (Cd(2+)), our knowledge on how they are transported into the vacuole is still insufficient. It has been suggested that Cd(2+) can be transported as phytochelatin-Cd(2+) by an unknown ABC transporter or in exchange with protons by cation/proton exchanger (CAX) transporters. To unravel the contribution of vacuolar transporters to Cd(2+) detoxification, a quantitative proteomics approach was performed. Highly purified vacuoles were isolated from barley plants grown under minus, low (20 microM), and high (200 microM) Cd(2+ )conditions and protein levels of the obtained tonoplast samples were analyzed using isobaric tag for relative and absolute quantitation (iTRAQ). Although 56 vacuolar transporter proteins were identified, only a few were differentially expressed. Under low-Cd(2+) conditions, an inorganic pyrophosphatase and a gamma-tonoplast intrinsic protein (gamma-TIP) were up-regulated, indicating changes in energization and water fluxes. In addition, the protein ratio of a CAX1a and a natural resistance-associated macrophage protein (NRAMP), responsible for vacuolar Fe(2+) export was increased. CAX1a might play a role in vacuolar Cd(2+) transport. An increase in NRAMP activity leads to a higher cytosolic Fe(2+) concentration, which may prevent the exchange of Fe(2+) by toxic Cd(2+). Additionally, an ABC transporter homolog to AtMRP3 showed up-regulation. Under high Cd(2+) conditions, the plant response was more specific. Only a protein homologous to AtMRP3 that showed already a response under low Cd(2+) conditions, was up-regulated. Interestingly, AtMRP3 is able to partially rescue a Cd(2+)-sensitive yeast mutant. The identified transporters are good candidates for further investigation of their roles in Cd(2+) detoxification. AbstractAlthough the vacuole is the most important final store for toxic heavy metals like cadmium (Cd 2+ ), our knowledge on how they are transported into the vacuole is still scarce. It has been suggested that Cd 2+ can be transported either as phytochelatin-Cd 2+ by an unknown ABC transporter or in exchange with protons by CAX transporters. To unravel the contribution of vacuolar transporters to Cd 2+ detoxification, a quantitative proteomics approach was performed.Highly purified vacuoles were isolated from barley plants grown under minus, low (20 µM), and high (200 µM) Cd 2+ conditions and protein levels of the obtained tonoplast samples were analyzed using iTRAQ TM . Although, 56 vacuolar transporter proteins were identified, however only a few were differentially expressed. Under low-Cd 2+ conditions an inorganic pyrophosphatase and a γ-tonoplast intrinsic protein (γ-TIP) were upregulated, indicating changes in energization and water fluxes. In addition, the protein ratio of a calcium/proton exchanger (CAX1a) and an NRAMP, responsible for vacuolar Fe 2+ export were increased. CAX1a might play a role in vacuolar Cd 2+ transport. An increase in NRAMP activity leads to a higher cytosol...

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The Syntaxin Homolog AtPEP12p Resides on a Late Post-Golgi Compartment in Plants

Cited by 48 publications

References 9 publications

Overexpression of theArabidopsisSyntaxin PEP12/SYP21 Inhibits Transport from the Prevacuolar Compartment to the Lytic Vacuole in Vivo

Overexpression of theArabidopsisSyntaxin PEP12/SYP21 Inhibits Transport from the Prevacuolar Compartment to the Lytic Vacuole in Vivo

Isolation and proteomic analysis of the SYP61 compartment reveal its role in exocytic trafficking in Arabidopsis

Quantitative detection of changes in the leaf‐mesophyll tonoplast proteome in dependency of a cadmium exposure of barley (Hordeum vulgare L.) plants

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