Dataset Information

Interactions between Transport Protein Particle (TRAPP) complexes and Rab GTPases in Arabidopsis

ABSTRACT: The Transport Protein Particle II (TRAPPII) is essential for exocytosis, endocytosis, protein sorting and cytokinesis. In spite of a considerable understanding of its biological role, little is known about Arabidopsis TRAPPII complex topology and molecular function. In this study, independent proteomic approaches initiated with TRAPP components or Rab-A GTPase variants converge on the TRAPPII complex. We show that the Arabidopsis genome encodes the full complement of 13 TRAPPC subunits, including four previously unidentified components. A dimerization model is proposed to account for binary interactions between TRAPPII subunits. Preferential binding to dominant negative (GDP-bound) versus wild-type or constitutively active (GTP-bound) RAB-A2a variants discriminates between TRAPPII and TRAPPIII subunits and shows that Arabidopsis complexes differ from yeast but resemble metazoan TRAPP complexes. While the TRAPPII complex has been implicated in biosynthetic pathways, TRAPPIII appears to be implicated in degradative pathways. Analyses of Rab-A variants in trappii backgrounds provide genetic evidence for the conclusion that the TRAPPII complex behaves as a Guanine-nucleotide Exchange Factor (GEF) for the RAB-A2a GTPase. GEFs catalyze exchange of GDP for GTP; the GTP-bound, activated, Rab then recruits a diverse local network of Rab effectors to specify membrane identity in subsequent vesicle fusion events. Understanding the control of GEF-Rab interactions will be crucial to unraveling the co-ordination of membrane traffic.

INSTRUMENT(S): LTQ Orbitrap Velos

ORGANISM(S): Arabidopsis Thaliana (mouse-ear Cress)

TISSUE(S): Flower, Root

SUBMITTER: Christina Ludwig

LAB HEAD: Christina Ludwig

PROVIDER: PXD013016 | Pride | 2019-09-03

REPOSITORIES: Pride

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Publications

Interactions between Transport Protein Particle (TRAPP) complexes and Rab GTPases in Arabidopsis.

Kalde Monika M Elliott Liam L Ravikumar Raksha R Rybak Katarzyna K Altmann Melina M Klaeger Susan S Wiese Christian C Abele Miriam M Al Benjamin B Kalbfuß Nils N Qi Xingyun X Steiner Alexander A Meng Chen C Zheng Huanquan H Kuster Bernhard B Falter-Braun Pascal P Ludwig Christina C Moore Ian I Assaad Farhah F FF

The Plant journal : for cell and molecular biology 20190805 2

Transport Protein Particle II (TRAPPII) is essential for exocytosis, endocytosis, protein sorting and cytokinesis. In spite of a considerable understanding of its biological role, little information is known about Arabidopsis TRAPPII complex topology and molecular function. In this study, independent proteomic approaches initiated with TRAPP components or Rab-A GTPase variants converge on the TRAPPII complex. We show that the Arabidopsis genome encodes the full complement of 13 TRAPPC subunits, ...[more]

PMID: 31264742

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Project description:Rationale: Endothelial cells (ECs) line the inner surface of continuous capillaries and form a permselective barrier between blood and tissues to limit paracellular fluid and solute flux. The capillary barrier is maintained by intercellular tight junctions (TJs) which are regulated, in part, by differential activity of small GTPases. Tumor necrosis factor (TNF) causes TJ disassembly in a process dependent upon NF-κB-mediated gene expression. Activated (GTP-bound) RhoB has been identified as a downstream effector of TNF-induced leak both through Rho-associated coiled-coil kinase-mediated phosphorylation of RelA, enhancing TNF-induced NF-κB-mediated gene activation, and through sequestration of Rac1 away from the cell junction, preventing barrier restoration. To date, no TNF-induced, RhoB-selective GTP exchange factor (GEF) has been identified in ECs. Objective: Identify a TNF-induced RhoB specific GEF in capillary ECs. Method and Results: human dermal microvascular ECs (HDMECs) were used because they form TJs. Candidate GEFs were identified by whole transcriptome profiling of HDMECs with or without TNF stimulation. Fifty-seven of 73 known GEFs were expressed in HDMECs and 17 were significantly upregulated by TNF. Functional impact of each of the latter group was assessed by measuring the effects of depletion by short interfering RNA knockdown on TNF-induced reduction of trans-endothelial electrical resistance (TEER) of HDMEC monolayers. Depletions of ArhGEF10 or RhoB or double depletion of ArhGEF10/RhoB similarly decreased TNF-mediated reduction of TEER. ArhGEF10 knockdown prevented TNF-induced disruption of TJ proteins assessed by confocal microscopy. TNF-induced increases in the levels of activated RhoB in HDMEC lysates were markedly reduced with only minimal alterations in RhoA or RhoC activation. Finally, immunoisolated ArhGEF10 selectively catalyzed GTP exchange for GDP in RhoB, but not RhoA or RhoC, in vitro. Conclusion: ArhGEF10 is a TNF-induced RhoB-selective GEF for RhoB in cultured human capillary ECs that contributes to TJ disruption.

Dataset Information

Interactions between Transport Protein Particle (TRAPP) complexes and Rab GTPases in Arabidopsis

Publications

Interactions between Transport Protein Particle (TRAPP) complexes and Rab GTPases in Arabidopsis.

Similar Datasets

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