The PP2A phosphatase associates with the Arabidopsis TRAPPII tethering complex and dephosphorylates a TRAPPII-derived phosphopeptide in vitro
- 1Biotechnology of Natural Products, TUM School of Life Sciences, Technical University of Munich, Freising, Germany
Abstract
The transport protein particle II (TRAPPII) complex is a conserved regulator of post-Golgi membrane trafficking. In Arabidopsis, phosphorylation of the TRAPPII-specific subunit TRS120 by SHAGGY-like kinases modulates adaptive growth responses, but the phosphatases that reverse this phosphorylation remain unknown. Here, proteomic analyses identified subunits of Protein Phosphatase 2A (PP2A) in the TRAPPII interactome. PP2A subunits physically associated with TRAPPII, and double-mutant analyses revealed genetic interactions between PP2A and TRAPPII. Loss of TRAPPII function reduced the relative membrane association of PP2A scaffolding subunits. We established an in vitro assay for Arabidopsis PP2A holoenzyme activity using complexes transiently co-expressed and affinity-purified from Nicotiana benthamiana. Structural modelling and interface analysis predicted binding of a phosphorylated peptide encompassing a TRS120 phosphosite cluster at the PP2A catalytic interface, while biochemical assays showed that a PP2A holoenzyme containing the B2 regulatory subunit dephosphorylated this peptide. Together, these findings identify a B2-containing PP2A holoenzyme as a candidate phosphatase for TRS120 and support a model in which antagonistic SHAGGY-like kinase and PP2A activities couple signalling to membrane trafficking during plant development and environmental adaptation.
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BibTeX
@misc{strohmayr2026pp2a,
title = {{The PP2A phosphatase associates with the Arabidopsis TRAPPII tethering complex and dephosphorylates a TRAPPII-derived phosphopeptide in vitro}},
author = {A. Strohmayr and A. Steiner and C. Wiese and M. Abele and E. Facher and K. Belcram and M. Altmann and P. Falter-Braun and C. Ludwig and M. Pastuglia and D. Bouchez and F. F. Assaad},
howpublished = {bioRxiv},
year = {2026},
month = sep,
doi = {10.64898/2026.09.03.749138},
url = {https://www.biorxiv.org/content/10.64898/2026.09.03.749138v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - The PP2A phosphatase associates with the Arabidopsis TRAPPII tethering complex and dephosphorylates a TRAPPII-derived phosphopeptide in vitro
AU - A. Strohmayr
AU - A. Steiner
AU - C. Wiese
AU - M. Abele
AU - E. Facher
AU - K. Belcram
AU - M. Altmann
AU - P. Falter-Braun
AU - C. Ludwig
AU - M. Pastuglia
AU - D. Bouchez
AU - F. F. Assaad
PY - 2026
DA - 2026/09/03
PB - bioRxiv
DO - 10.64898/2026.09.03.749138
UR - https://www.biorxiv.org/content/10.64898/2026.09.03.749138v1
AB - The transport protein particle II (TRAPPII) complex is a conserved regulator of post-Golgi membrane trafficking. In Arabidopsis, phosphorylation of the TRAPPII-specific subunit TRS120 by SHAGGY-like kinases modulates adaptive growth responses, but the phosphatases that reverse this phosphorylation remain unknown. Here, proteomic analyses identified subunits of Protein Phosphatase 2A (PP2A) in the TRAPPII interactome. PP2A subunits physically associated with TRAPPII, and double-mutant analyses revealed genetic interactions between PP2A and TRAPPII. Loss of TRAPPII function reduced the relative membrane association of PP2A scaffolding subunits. We established an in vitro assay for Arabidopsis PP2A holoenzyme activity using complexes transiently co-expressed and affinity-purified from Nicotiana benthamiana. Structural modelling and interface analysis predicted binding of a phosphorylated peptide encompassing a TRS120 phosphosite cluster at the PP2A catalytic interface, while biochemical assays showed that a PP2A holoenzyme containing the B2 regulatory subunit dephosphorylated this peptide. Together, these findings identify a B2-containing PP2A holoenzyme as a candidate phosphatase for TRS120 and support a model in which antagonistic SHAGGY-like kinase and PP2A activities couple signalling to membrane trafficking during plant development and environmental adaptation.
ER -