Tropomyosin 1 and End-binding protein 1 in mRNA transport

点击翻译按钮获取中文摘要

During the first funding period we were able to show that many of the recently discovered novel RNA binding proteins (RBPs), which do not comprise any classical RNA binding domain are indeed able to bind RNA in vitro. Furthermore, we could demonstrate that nuclear magnetic resonance spectroscopy is an excellent method to validate RNA binding proteins and would advice a thorough in vitro validation of RNA binding proteins before starting a new project on novel RNA binding proteins. Two of the novel RNA binding proteins, Tropomyosin 1 and End-binding protein 1 (EB1) we could verify to be intrinsic RNA binding proteins. Tropomyosin 1 is essential for RNA transport as an adaptor protein for RNA to be transported to its final destination in the cell. Here, RNA binds via Tropomyosin 1 to Kinesin, which moves along microtubules. During the first funding period, we could solve the first high-resolution structure of a Kinesin-adaptor (Tropomyosin 1) protein complex via X-ray crystallography, which provides tremendous insights into the transport mechanism. Additionally, we could identify the RNA binding region of Tropomyosin 1. This enables us to pursue targeted functional studies in fruit flies, to understand the entire mechanism of RNA transport in molecular detail. Also, we aim to determine a ternary complex structure of Kinesin, Tropomyosin and RNA.Regarding EB1, we could not only verify its RNA binding, but also determine the exact region of binding on the protein surface. This overlaps with the binding site to microtubules. Moreover, the linker within EB1 interacts via a threonine with its N-terminal domain. This threonine is known to be phosphorylated, which might be an activity switch of EB1. In the second funding period we will follow this up with detailed mutational analyses in vitro and in vivo, to understand the influence of phosphorylation and RNA binding of EB1 on microtubule assembly.