PhD defence: Ida Sjøgaard

Title: Functional Analysis of Structural Elements of ARGONAUTE1 in Arabidopsis thaliana

Abstract: The thesis starts out with a general introduction to the biology of the diverse small RNA silencing pathways followed by four research chapters. The first two chapters are shared first- author manuscripts which we have submitted to Nature Structural & Molecular Biology and Biochemical Journal, respectively. Here, we focus on a short, confined stretch of the N- terminus of ARGONAUTE 1 implicated in distinguishing RNA-free from sRNA-loaded ARGONAUTE protein. Furthermore, in the second manuscript we identify interaction sites on the N domain of Arabidopsis thaliana ARGONAUTE 1 for a group of proteins associated with regulated proteolytic pathways. The third chapter is a manuscript in preparation where we have obtained a structure of ARGONAUTE 1 in complex with the chaperone HSP70. This interaction is dependent on a protein-protein interaction site known from metazoan Argonaute proteins. The last chapter examines the function of this protein interaction site in relation to secondary siRNA biogenesis factors. Lastly, the thesis is closed by final conclusions and perspectives. All chapters are written in the format of manuscripts.

Supervisor: Prof. Peter Brodersen

Assessment Committee:
Chair – Prof. Xu Peng
External opponents – Prof. Ditlev Brodersen and Prof. Dina Grohmann