Vacuolar H+-ATPase Activity Is Required for Endocytic and Secretory Trafficking inArabidopsis

Abstract

In eukaryotic cells, compartments of the highly dynamic endomembrane system are acidified to varying degrees by the activity of vacuolar H þ -ATPases (V-ATPases). In the Arabidopsis thaliana genome, most V-ATPase subunits are encoded by small gene families, thus offering potential for a multitude of enzyme complexes with different kinetic properties and localizations. We have determined the subcellular localization of the three Arabidopsis isoforms of the membrane-integral V-ATPase subunit VHA-a. Colocalization experiments as well as immunogold labeling showed that VHA-a1 is preferentially found in the trans-Golgi network (TGN), the main sorting compartment of the secretory pathway. Uptake experiments with the endocytic tracer FM4-64 revealed rapid colocalization with VHA-a1, indicating that the TGN may act as an early endosomal compartment. Concanamycin A, a specific V-ATPase inhibitor, blocks the endocytic transport of FM4-64 to the tonoplast, causes the accumulation of FM4-64 together with newly synthesized plasma membrane proteins, and interferes with the formation of brefeldin A compartments. Furthermore, nascent cell plates are rapidly stained by FM4-64, indicating that endocytosed material is redirected into the secretory flow after reaching the TGN. Together, our results suggest the convergence of the early endocytic and secretory trafficking pathways in the TGN.

Myosins XI modulate host cellular responses and penetration resistance to fungal pathogens

“…We further examined effects of NEM treatment on the vesicle trafficking pathways, including transports of ARA6-GFP-tagged vesicles to plasma membrane (34), GFP-ARA7-tagged vesicles to multivesicular body (35), VHA-a1-GFP-tagged vesicles to transGolgi network (36), and GFP-VAMP727-tagged vesicles to vacuole (37). Each of these four vesicle classes aggregated toward the fungal attack site, indicating that localized delivery of a broad range of membrane-bound cargoes is triggered by penetration attempts.…”

TNO1 Is Involved in Salt Tolerance and Vacuolar Trafficking in Arabidopsis

“…In Arabidopsis, the trafficking inhibitor BFA targets the Arf-GEF GNOM and induces the formation of BFA compartments (Geldner et al, 2001), most likely by homotypic fusion of the TGN (which is also an early endosome) and heterotypic fusion between the TGN and other endosomes (Dettmer et al, 2006;Lam et al, 2009;Viotti et al, 2010). Therefore, SNAREs at the TGN mayfunction in these fusion events upon BFA treatment.…”

“…The localization of SYP61 and SYP41 was investigated in wild-type and tno1 mutant protoplasts. Previously, SYP61 has been shown to colocalize with VHAa1-GFP (Dettmer et al, 2006). To investigate the localization of SYP61 in the tno1 mutant, a VHAa1-GFP transgenic tno1 mutant was generated.…”

Peculiar features of plant cell vacuolar H+-ATPase regulation

“…У растений протонная V-АТФаза локализована на тонопласте, и ее основопо-лагающая роль заключается в поддержании ионного и метаболического гомеоста-за посредством создания мембранного потенциала на вакуолярной мембране [10,11]. Наряду с тонопластом данный фермент идентифицируется в мембранах эндо-плазматического ретикулума, аппарата Гольджи, провакуолей и т. д. Растительные V-АТФазы принимают участие в процессах эндо-и экзоцитоза и играют важную роль в регуляции эмбрионального развития и роста клеток растяжением [10][11][12].…”

“…Наряду с тонопластом данный фермент идентифицируется в мембранах эндо-плазматического ретикулума, аппарата Гольджи, провакуолей и т. д. Растительные V-АТФазы принимают участие в процессах эндо-и экзоцитоза и играют важную роль в регуляции эмбрионального развития и роста клеток растяжением [10][11][12].…”