Structural and biochemical investigations of the Brassinosteroid (BR) pathway in Arabidopsis thaliana

• Applicant: Dr. Marco Bürger
• Subject Area: Plant Cell and Developmental Biology ; Plant Biochemistry and Biophysics ; Structural Biology
• Term: from 2013 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 239742070

The demand for food, feed, fiber, and fuel has placed agriculture at the center of grand challenges for this century. During the past 15 years, the mechanisms by which small molecule phytohormones regulate growth have been elucidated in Arabidopsis. Among them, the growth-promoting brassinosteroid (BR) pathway is one of the best-defined signal transduction pathways in plants. The receptor and its signaling components are known, but a detailed description of protein-protein interactions during receptor activation is lacking.Activation of the receptor leads to phosphorylation of at least 2 proteins: BSK1 and CDG1. A recent study revealed that BSK1 activates a further protein, BSU1, by phosphorylation. However, it remains unclear at the moment if BSK1 is a real kinase, which functions on its own or if it acts together with a third protein, CDG1. Thus, my research will try to answer the following questions:1. Are BSKs protein kinases? 2. Are CDG, BSK and BSU in direct contact with each other and do they require contact with an activated BRI1/BAK1/BR to signal? 3. What are the protein-protein interaction domains of CDG, BSK, and CDG1?These problems will be mainly addressed by means of X-ray protein crystallography and biochemical methods like kinase activity assays. The successful completion of the proposed experiments will close the final gap in the BR signaling pathway, a key pathway that determines the size of plants and the results should have very high impact to explain the phenotypic plasticity of plants. An added bonus in my case is that I will learn Arabidopsis genetics and can add plant techniques to my laboratory skill set.

• DFG Programme: Research Fellowships
• International Connection: USA
• Host: Professorin Dr. Joanne Chory