Evaluation of Defective Endosomal Trafficking to the Vacuole by Monitoring Seed Storage Proteins in Arabidopsis thaliana

Shimada, Tomoo; Koumoto, Yasuko; Hara‐Nishimura, Ikuko

doi:10.1007/978-1-4939-1420-3_10

Cited by 3 publications

(2 citation statements)

References 16 publications

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“…The GFP fluorescence of dry seeds was observed as described previously (Fuji et al, 2007). The immunoelectron microscopic analysis of dry seeds was performed as described previously (Li et al, 2013;Shimada et al, 2014).…”

Section: Confocal Laser Scanning Microscopy and Electron Microscopymentioning

confidence: 99%

The Adaptor Complex AP-4 Regulates Vacuolar Protein Sorting at the trans-Golgi Network by Interacting with VACUOLAR SORTING RECEPTOR1

et al. 2015

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Adaptor protein (AP) complexes play critical roles in protein sorting among different post-Golgi pathways by recognizing specific cargo protein motifs. Among the five AP complexes (AP-1-AP-5) in plants, AP-4 is one of the most poorly understood; the AP-4 components, AP-4 cargo motifs, and AP-4 functional mechanism are not known. Here, we identify the AP-4 components and show that the AP-4 complex regulates receptor-mediated vacuolar protein sorting by recognizing VACUOLAR SORTING RECEPTOR1 (VSR1), which was originally identified as a sorting receptor for seed storage proteins to target protein storage vacuoles in Arabidopsis (Arabidopsis thaliana). From the vacuolar sorting mutant library GREEN FLUORESCENT SEED (GFS), we isolated three gfs mutants that accumulate abnormally high levels of VSR1 in seeds and designated them as gfs4, gfs5, and gfs6. Their responsible genes encode three (AP4B, AP4M, and AP4S) of the four subunits of the AP-4 complex, respectively, and an Arabidopsis mutant (ap4e) lacking the fourth subunit, AP4E, also had the same phenotype. Mass spectrometry demonstrated that these four proteins form a complex in vivo. The four mutants showed defects in the vacuolar sorting of the major storage protein 12S globulins, indicating a role for the AP-4 complex in vacuolar protein transport. AP4M bound to the tyrosine-based motif of VSR1. AP4M localized at the trans-Golgi network (TGN) subdomain that is distinct from the AP-1-localized TGN subdomain. This study provides a novel function for the AP-4 complex in VSR1-mediated vacuolar protein sorting at the specialized domain of the TGN.

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Section: Confocal Laser Scanning Microscopy and Electron Microscopymentioning

confidence: 99%

The Adaptor Complex AP-4 Regulates Vacuolar Protein Sorting at the trans-Golgi Network by Interacting with VACUOLAR SORTING RECEPTOR1

et al. 2015

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“…Thin sections were prepared as described previously 26 with the upper parts (1–3 cm from the top) of the primary inflorescence stem (14 cm height). The sections were stained with 1% Toluidine Blue 27 and were observed in a bright field with a light microscope (Axioplan 2 Imaging; Zeiss) using objectives (20 × 0.5 NA and 10 × 0.3 NA).…”

Section: Methodsmentioning

confidence: 99%

An ABC transporter B family protein, ABCB19, is required for cytoplasmic streaming and gravitropism of the inflorescence stems

Okamoto

Ueda

Shimada

et al. 2016

Plant Signaling & Behavior

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A significant feature of plant cells is the extensive motility of organelles and the cytosol, which was originally defined as cytoplasmic streaming. We suggested previously that a three-way interaction between plant-specific motor proteins myosin XIs, actin filaments, and the endoplasmic reticulum (ER) was responsible for cytoplasmic streaming.1 Currently, however, there are no reports of molecular components for cytoplasmic streaming other than the actin-myosin-cytoskeleton and ER-related proteins. In the present study, we found that elongated cells of inflorescence stems of Arabidopsis thaliana exhibit vigorous cytoplasmic streaming. Statistical analysis showed that the maximal velocity of plastid movements is 7.26 µm/s, which is much faster than the previously reported velocities of organelles. Surprisingly, the maximal velocity of streaming in the inflorescence stem cells was significantly reduced to 1.11 µm/s in an Arabidopsis mutant, abcb19-101, which lacks ATP BINDING CASSETTE SUBFAMILY B19 (ABCB19) that mediates the polar transport of the phytohormone auxin together with PIN-FORMED (PIN) proteins. Polar auxin transport establishes the auxin concentration gradient essential for plant development and tropisms. Deficiency of ABCB19 activity eventually caused enhanced gravitropic responses of the inflorescence stems and abnormally flexed inflorescence stems. These results suggest that ABCB19-mediated auxin transport plays a role not only in tropism regulation, but also in cytoplasmic streaming.

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Multifaceted roles of Arabidopsis heat shock factor binding protein in plant growth, development, and heat shock response

Huang,

Liu,

et al. 2024

Environmental and Experimental Botany

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Evaluation of Defective Endosomal Trafficking to the Vacuole by Monitoring Seed Storage Proteins in Arabidopsis thaliana

Cited by 3 publications

References 16 publications

The Adaptor Complex AP-4 Regulates Vacuolar Protein Sorting at the trans-Golgi Network by Interacting with VACUOLAR SORTING RECEPTOR1

The Adaptor Complex AP-4 Regulates Vacuolar Protein Sorting at the trans-Golgi Network by Interacting with VACUOLAR SORTING RECEPTOR1

An ABC transporter B family protein, ABCB19, is required for cytoplasmic streaming and gravitropism of the inflorescence stems

Multifaceted roles of Arabidopsis heat shock factor binding protein in plant growth, development, and heat shock response

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