Role of the Arabidopsis TRAPPII tethering complex in division plane establishment

• Applicant: Professorin Farhah Assaad, Ph.D.
• Subject Area: Plant Cell and Developmental Biology ; Cell Biology
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 505695129

In plants, the position of the interphase nucleus determines the division plane prior to mitotic entry. Later in the cell cycle, nascent cross walls are assembled in a transient membrane compartment referred to as the cell plate. The Arabidopsis transport protein particle TRAPPII tethering complex is required for both division plane establishment and cell plate formation. We have screened for conditional protein-protein interactions using TRAPPII as bait and have validated interesting candidates. Our preliminary data has led to the working model that TRAPPII is a target of GSK3/shaggy-like kinases (AtSKs) and PP2A phosphatases. We posit that a TRAPPII phosphocode mediates the spatiotemporal control of plant cytokinesis. This grant focuses on division plane establishment and on the TRAPPII-PP2A interaction; PP2A is a component of the TON/TRM/PP2A complex, which is required for cross wall orientation. Our specific aims are to (1) elucidate the role of TRAPPII in division plane establishment, (2) elucidate the role of PP2A in regulating TRAPPII localization and function, (3) establish whether TRAPPII is a PP2A phosphatase substrate. We will combine molecular, genetic, cell biological, biochemical and proteomic approaches to address these goals. The AtSK and PP2A gene families integrate a vast number of biotic and abiotic signals and could thereby instruct trafficking, mobilization and sorting decisions via the TRAPPII phosphocode. In addition to new insights on division plane establishment, this study will more broadly elucidate how, downstream of shaggy-like kinases and PP2A, TRAPPII regulates trafficking in response to environmental and developmental cues.

• DFG Programme: Research Grants