Analysis of molecular and cellular mechanisms regulating CKX activity in plants

• Applicant: Professor Dr. Tomás Werner
• Subject Area: Plant Cell and Developmental Biology
• Term: from 2011 to 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 209897667

The concentration of the plant hormone cytokinin is effectively controlled through oxidative degradation catalyzed by cytokinin oxidase/dehydrogenase (CKX) enzymes. Although the general understanding of this metabolic pathway is at hand, molecular mechanisms underlying CKX activity have not been well studied and developmental processes controlled predominantly by the CKX pathway are not comprehensively revealed. In our preparatory work, we achieved to establish plants with suppressed CKX1 gene activity and identified developmental traits – such as embryogenesis, gametogenesis and lateral root development – strongly affected in these plants. A profound dissection of CKX1-controlled developmental programs, as well as the functional interplay of CKX1 with other regulatory pathways, is one focus of this project. The biological relevance of the cis-encoded CKX1 natural antisense transcript will be investigated. Experiments addressing the principal aspects of CKX protein functioning with respect to protein-to-membrane association and subcellular localization, as well as the role of N-glycosylation for cellular targeting and enzyme activity, will be carried out. We demonstrated that CKX1 interacts with several HIPP proteins characterized by the combined occurrence of a heavy metal-associated domain and an isoprenylation motif. Biochemical and in vivo analyses will be employed to characterize the function of isolated HIPP proteins, specifically pinpointing their relevance for CKX activity and plant cytokinin responses.

• DFG Programme: Research Grants