The Arabidopsis V-ATPase is localized to the TGN/EE via a seed plant-specific motif

• Main Authors: Upendo Lupanga, Rachel Röhrich, Jana Askani, Stefan Hilmer, Christiane Kiefer, Melanie Krebs, Takehiko Kanazawa, Takashi Ueda, Karin Schumacher
• Format: Article
• Language: English
• Published: eLife Sciences Publications Ltd 2020-11-01
• Series: eLife
• Subjects: V-ATPase; targeting; TGN/EE; Marchantia polymorpha; proton pump; CRISPR
• Online Access: https://elifesciences.org/articles/60568

The V-ATPase is a versatile proton-pump found in a range of endomembrane compartments yet the mechanisms governing its differential targeting remain to be determined. In Arabidopsis, VHA-a1 targets the V-ATPase to the TGN/EE whereas VHA-a2 and VHA-a3 are localized to the tonoplast. We report here that the VHA-a1 targeting domain serves as both an ER-exit and as a TGN/EE-retention motif and is conserved among seed plants. In contrast, Marchantia encodes a single VHA-isoform that localizes to the TGN/EE and the tonoplast in Arabidopsis. Analysis of CRISPR/Cas9 generated null alleles revealed that VHA-a1 has an essential function for male gametophyte development but acts redundantly with the tonoplast isoforms during vegetative growth. We propose that in the absence of VHA-a1, VHA-a3 is partially re-routed to the TGN/EE. Our findings contribute to understanding the evolutionary origin of V-ATPase targeting and provide a striking example that differential localization does not preclude functional redundancy.