Overexpression of Auxin-Binding Protein Enhances the Sensitivity of Guard Cells to Auxin

Bauly, James; Sealy, Ian; Macdonald, Heather; Brearley, Jane; Dröge, Swenja; Hillmer, Stefan; Robinson, David G.; Venis, Michael A.; Blatt, Michael R.; Lazarus, Colin M.; Napier, Richard

doi:10.1104/pp.124.3.1229

Cited by 94 publications

(53 citation statements)

References 58 publications

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“…Whereas ␣-amylase was distributed evenly among the Golgi stacks, ␣-amylase-HDEL was enriched specifically in the cis-most Golgi and to a lesser extent in the cis-Golgi (Figure 1). The strong statistical analysis shown in Figure 1 adds further weight to previous results on the distribution of the auxin binding protein (a KDEL protein), which is localized predominantly in the cis-Golgi (Bauly et al, 2000). This was observed as well when KDEL was replaced by HDEL, but not when the signal was rendered nonfunctional (KEQL or KDELGL).…”

Section: A Model System For Anterograde and Retrograde Er-to-golgi Trsupporting

confidence: 68%

Secretory Bulk Flow of Soluble Proteins Is Efficient and COPII Dependent

Phillipson¹,

Pimpl²,

daSilva³

et al. 2001

The Plant Cell

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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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Section: A Model System For Anterograde and Retrograde Er-to-golgi Trsupporting

confidence: 68%

Secretory Bulk Flow of Soluble Proteins Is Efficient and COPII Dependent

Phillipson¹,

Pimpl²,

daSilva³

et al. 2001

The Plant Cell

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159

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“…3 and 4). The few studies that have examined specific transport activities directly, for example, of outward-rectifying K + currents in intact guard cells of V. faba, tobacco (Nicotiana tabacum), and Arabidopsis (Blatt, 1988b;Armstrong et al, 1995;Blatt and Gradmann, 1997;Blatt et al, 1999;Ache et al, 2000;Bauly et al, 2000;Johansson et al, 2006;Chen et al, 2012b;Eisenach et al, 2012Eisenach et al, , 2014, indicate substantial variations between species independent of surface area. These comparisons call in question the validity of assuming a priori that transport activity remains constant on a unit-surface-area basis.…”

Section: Ion Transport Stomatal Response and Wuementioning

confidence: 99%

Stomatal Size, Speed, and Responsiveness Impact on Photosynthesis and Water Use Efficiency

2014

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The control of gaseous exchange between the leaf and bulk atmosphere by stomata governs CO 2 uptake for photosynthesis and transpiration, determining plant productivity and water use efficiency. The balance between these two processes depends on stomatal responses to environmental and internal cues and the synchrony of stomatal behavior relative to mesophyll demands for CO 2 . Here we examine the rapidity of stomatal responses with attention to their relationship to photosynthetic CO 2 uptake and the consequences for water use. We discuss the influence of anatomical characteristics on the velocity of changes in stomatal conductance and explore the potential for manipulating the physical as well as physiological characteristics of stomatal guard cells in order to accelerate stomatal movements in synchrony with mesophyll CO 2 demand and to improve water use efficiency without substantial cost to photosynthetic carbon fixation. We conclude that manipulating guard cell transport and metabolism is just as, if not more likely to yield useful benefits as manipulations of their physical and anatomical characteristics. Achieving these benefits should be greatly facilitated by quantitative systems analysis that connects directly the molecular properties of the guard cells to their function in the field.In order for plants to function efficiently, they must balance gaseous exchange between inside and outside the leaf to maximize CO 2 uptake for photosynthetic carbon assimilation (A) and to minimize water loss through transpiration. Stomata are the "gatekeepers" responsible for all gaseous diffusion, and they adjust to both internal and external environmental stimuli governing CO 2 uptake and water loss. The pathway for CO 2 uptake from the bulk atmosphere to the site of fixation is determined by a series of diffusional resistances, which start with the layer of air immediately surrounding the leaf (the boundary layer). Stomatal pores provide a major resistance to flux from the atmosphere to the substomatal cavity within the leaf. Further resistance is encountered by CO 2 across the aqueous and lipid boundaries into the mesophyll cell and chloroplasts (mesophyll resistance). Water leaving the leaf largely follows the same pathway in reverse, but without the mesophyll resistance component. Guard cells surround the stomatal pore. They increase or decrease in volume in response to external and internal stimuli, and the resulting changes in guard cell shape adjust stomatal aperture and thereby affect the flux of gases between the leaf internal environment and the bulk atmosphere. Stomatal behavior, therefore, controls the volume of CO 2 entering the intercellular air spaces of the leaf for photosynthesis. It also plays a key role in minimizing the amount of water lost. Transpiration, by virtue of the concentration differences, is an order of magnitude greater than CO 2 uptake, which is an inevitable consequence of free diffusion across this pathway. Although the cumulative area of stomatal pores only represents a small fraction...

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“…When attached to the C terminus, the ER retrieval motif KDEL (Lys-Asp-Glu-Leu) allows glycoproteins to be retained in, or returned to, the ER. Although there are exceptions (14), in general, glycans attached to proteins containing a C-terminal KDEL sequence would be expected to be restricted mainly to the oligomannose type (13,15,16). ER retention of proteins in transgenic plants usually improves the production levels (9,17).…”

mentioning

confidence: 99%

Function and glycosylation of plant-derived antiviral monoclonal antibody

Tekoah

Rudd

et al. 2003

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

236

164

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Plant genetic engineering led to the production of plant-derived mAb (mAb P ), which provides a safe and economically feasible alternative to the current methods of antibody production in animal systems. In this study, the heavy and light chains of human anti-rabies mAb were expressed and assembled in planta under the control of two strong constitutive promoters. An alfalfa mosaic virus untranslated leader sequence and Lys-Asp-Glu-Leu (KDEL) endoplasmic reticulum retention signal were linked at the N and C terminus of the heavy chain, respectively. mAb P was as effective at neutralizing the activity of the rabies virus as the mammalianderived antibody (mAb M ) or human rabies Ig (HRIG). The mAb P contained mainly oligomannose type N-glycans (90%) and had no potentially antigenic ␣(1,3)-linked fucose residues. mAb P had a shorter half-life than mAb M . The mAb P was as efficient as HRIG for post-exposure prophylaxis against rabies virus in hamsters, indicating that differences in N-glycosylation do not affect the efficacy of the antibody in this model.

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Overexpression of Auxin-Binding Protein Enhances the Sensitivity of Guard Cells to Auxin

Cited by 94 publications

References 58 publications

Secretory Bulk Flow of Soluble Proteins Is Efficient and COPII Dependent

Secretory Bulk Flow of Soluble Proteins Is Efficient and COPII Dependent

Stomatal Size, Speed, and Responsiveness Impact on Photosynthesis and Water Use Efficiency

Function and glycosylation of plant-derived antiviral monoclonal antibody

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