scholarly journals Cardosin A contains two vacuolar sorting signals using different vacuolar routes in tobacco epidermal cells

2013 ◽  
pp. n/a-n/a ◽  
Author(s):  
Cláudia Pereira ◽  
Susana Pereira ◽  
Béatrice Satiat-Jeunemaitre ◽  
José Pissarra
Keyword(s):  
Epidermal Cells ◽  
Sorting Signals ◽  
Vacuolar Sorting ◽  
Cardosin A

scholarly journals Different sensitivity to wortmannin of two vacuolar sorting signals indicates the presence of distinct sorting machineries in tobacco cells.

1995 ◽  
Vol 130 (6) ◽  
pp. 1307-1318 ◽  
Author(s):  
K Matsuoka ◽  
D C Bassham ◽  
N V Raikhel ◽  
K Nakamura
Keyword(s):  
Secretory Pathway ◽  
Plant Cells ◽  
Specific Inhibitor ◽  
Matrix Proteins ◽  
Wild Type ◽  
Dose Dependency ◽  
Tobacco Cells ◽  
Sorting Signals ◽  
Vacuolar Sorting ◽  
Mature Part

Vacuolar matrix proteins in plant cells are sorted from the secretory pathway to the vacuoles at the Golgi apparatus. Previously, we reported that the NH2-terminal propeptide (NTPP) of the sporamin precursor and the COOH-terminal propeptide (CTPP) of the barley lectin precursor contain information for vacuolar sorting. To analyze whether these propeptides are interchangeable, we expressed constructs consisting of wild-type or mutated NTPP with the mature part of barley lectin and sporamin with CTPP and mutated NTPP in tobacco BY-2 cells. The vacuolar localization of these constructs indicated that the signals were interchangeable. We next analyzed the effect of wortmannin, a specific inhibitor of mammalian phosphatidylinositol (PI) 3-kinase on vacuolar delivery by NTPP and CTPP in tobacco cells. Pulse-chase analysis indicated that 33 microM wortmannin caused almost complete inhibition of CTPP-mediated transport to the vacuoles, while NTPP-mediated transport displayed almost no sensitivity to wortmannin at this concentration. This indicates that there are at least two different mechanisms for vacuolar sorting in tobacco cells, and the CTPP-mediated pathway is sensitive to wortmannin. We compared the dose dependencies of wortmannin on the inhibition of CTPP-mediated vacuolar delivery of proteins and on the inhibition of the synthesis of phospholipids in tobacco cells. Wortmannin inhibited PI 3- and PI 4-kinase activities and phospholipid synthesis. Missorting caused by wortmannin displays a dose dependency that is similar to the dose dependency for the inhibition of synthesis of PI 4-phosphate and major phospholipids. This is different, however, than the inhibition of synthesis of PI 3-phosphate. Thus, the synthesis of phospholipids could be involved in CTPP-mediated vacuolar transport.

scholarly journals N-Linked Glycosylation Modulates Golgi-Independent Vacuolar Sorting Mediated by the Plant Specific Insert

Plants ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 312 ◽  
Author(s):  
Vanessa Vieira ◽  
Bruno Peixoto ◽  
Mónica Costa ◽  
Susana Pereira ◽  
José Pissarra ◽  
...  
Keyword(s):  
Sequence Similarity ◽  
Site Directed Mutagenesis ◽  
Research Gaps ◽  
Glycosylation Pattern ◽  
High Sequence Similarity ◽  
Post Translational Modifications ◽  
Vacuolar Sorting ◽  
Prevacuolar Compartment ◽  
Cardosin A ◽  
Comprehensive Study

In plant cells, the conventional route to the vacuole involves the endoplasmic reticulum, the Golgi and the prevacuolar compartment. However, over the years, unconventional sorting to the vacuole, bypassing the Golgi, has been described, which is the case of the Plant-Specific Insert (PSI) of the aspartic proteinase cardosin A. Interestingly, this Golgi-bypass ability is not a characteristic shared by all PSIs, since two related PSIs showed to have different sensitivity to ER-to-Golgi blockage. Given the high sequence similarity between the PSI domains, we sought to depict the differences in terms of post-translational modifications. In fact, one feature that draws our attention is that one is N-glycosylated and the other one is not. Using site-directed mutagenesis to obtain mutated versions of the two PSIs, with and without the glycosylation motif, we observed that altering the glycosylation pattern interferes with the trafficking of the protein as the non-glycosylated PSI-B, unlike its native glycosylated form, is able to bypass ER-to-Golgi blockage and accumulate in the vacuole. This is also true when the PSI domain is analyzed in the context of the full-length cardosin. Regardless of opening exciting research gaps, the results obtained so far need a more comprehensive study of the mechanisms behind this unconventional direct sorting to the vacuole.

scholarly journals Lysosomal and vacuolar sorting: not so different after all!

2016 ◽  
Vol 44 (3) ◽  
pp. 891-897 ◽  
Author(s):  
Carine de Marcos Lousa ◽  
Jurgen Denecke
Keyword(s):  
Secretory Pathway ◽  
Early Stage ◽  
Model Systems ◽  
Cellular Damage ◽  
Plant Model ◽  
Sorting Signals ◽  
Vacuolar Sorting Receptors ◽  
Specific Receptors ◽  
Vacuolar Sorting ◽  
Eukaryotic Organisms

Soluble hydrolases represent the main proteins of lysosomes and vacuoles and are essential to sustain the lytic properties of these organelles typical for the eukaryotic organisms. The sorting of these proteins from ER residents and secreted proteins is controlled by highly specific receptors to avoid mislocalization and subsequent cellular damage. After binding their soluble cargo in the early stage of the secretory pathway, receptors rely on their own sorting signals to reach their target organelles for ligand delivery, and to recycle back for a new round of cargo recognition. Although signals in cargo and receptor molecules have been studied in human, yeast and plant model systems, common denominators and specific examples of diversification have not been systematically explored. This review aims to fill this niche by comparing the structure and the function of lysosomal/vacuolar sorting receptors (VSRs) from these three organisms.

scholarly journals The Plant Vacuolar Sorting Receptor Atelp Is Involved in Transport of Nh2-Terminal Propeptide-Containing Vacuolar Proteins in Arabidopsis thaliana

2000 ◽  
Vol 149 (7) ◽  
pp. 1335-1344 ◽  
Author(s):  
Sharif U. Ahmed ◽  
Enrique Rojo ◽  
Valentina Kovaleva ◽  
Sridhar Venkataraman ◽  
James E. Dombrowski ◽  
...  
Keyword(s):  
Arabidopsis Thaliana ◽  
Transgenic Arabidopsis ◽  
Sorting Signals ◽  
Specific Manner ◽  
Vacuolar Sorting Receptor ◽  
Vacuolar Sorting ◽  
Sorting Receptor ◽  
Vacuolar Protein ◽  
Golgi Network ◽  
Endogenous Plant

Many soluble plant vacuolar proteins are sorted away from secreted proteins into small vesicles at the trans-Golgi network by transmembrane cargo receptors. Cleavable vacuolar sorting signals include the NH2-terminal propeptide (NTPP) present in sweet potato sporamin (Spo) and the COOH-terminal propeptide (CTPP) present in barley lectin (BL). These two proteins have been found to be transported by different mechanisms to the vacuole. We examined the ability of the vacuolar cargo receptor AtELP to interact with the sorting signals of heterologous and endogenous plant vacuolar proteins in mediating vacuolar transport in Arabidopsis thaliana. AtELP extracted from microsomes was found to interact with the NTPPs of barley aleurain and Spo, but not with the CTPPs of BL or tobacco chitinase, in a pH-dependent and sequence-specific manner. In addition, EM studies revealed the colocalization of AtELP with NTPP-Spo at the Golgi apparatus, but not with BL-CTPP in roots of transgenic Arabidopsis plants. Further, we found that AtELP interacts in a similar manner with the NTPP of the endogenous vacuolar protein AtALEU (Arabidopsis thaliana Aleu), a protein highly homologous to barley aleurain. We hypothesize that AtELP functions as a vacuolar sorting receptor involved in the targeting of NTPP-, but not CTPP-containing proteins in Arabidopsis.

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