Recruitment and phospho-regulation of key division site proteins in plants

• Applicant: Dr. Sabine Müller
• Subject Area: Plant Cell and Developmental Biology
• Term: from 2018 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 393727146

Plant cells select their division planes before mitosis, marking the circumferences by the cytoskeletal preprophase band and by an assembly of proteins termed division site resident proteins. Core components of this protein complex located at the cell cortex are the kinesin-12 proteins PHRAGMOPLAST ORIENTING KINESINs (POKs), which continuously occupy the division site. POKs are essential for the maintenance of the division site, but we know little about their recruitment to the predetermined site. How the division plane is selected in plants is still one of the unsolved questions in plant cell biology. The proposed research aims to improve our understanding of division plane determination using POKs as a proxy. We will investigate whether POKs are phospho-regulated throughout the course of cell division and how this regulation affects their localization and dynamicity. Moreover, we will examine whether this regulation involves the activity of protein phosphatase 2A complex, that is essential for preprophase band formation. Several of its components are direct binding partners of POKs. Furthermore, we will characterize novel, unexpected interactions between POKs and members of the BELL-like transcription factor family that might contribute to division plane determination. To accomplish these goals, we will employ life-cell microscopy and use advanced imaging techniques in combination with genetic and biochemical approaches. We expect to elucidate the relevance phospho-regulation for the establishment of the division site and to identify a novel mechanism that might encompass a pathway of division plane determination, and that might act independent of the preprophase band.

• DFG Programme: Research Grants