Research Group Niessing

Imagine a big city without a car driving and no mail being delivered. The resulting chaos is similar to what happens to a cell when its molecular transport systems are impaired. Our goal is to understand the molecular principles underlying cargo recognition by transport complexes, complex assembly and activation, and eventually complex disassembly after the transport. Our research tools are X-ray crystallography, quantitative biophysical approaches, biochemistry, and in vivo studies.

As a first model, we analyze the directional transport of ASH1 mRNA in S. cerevisiae. Besides mRNA, this cargo-transport complex consists of the myosin motor Myo4p, its bound adapter She3p, and the RNA-cargo binding protein She2p. We determined crystal structures of She2p and Myo4p, and performed functional analysis on the assembly of this complex. Recently, we succeeded in reconstituting functional subcomplexes that allowed us to understand how specific recognition of cargo RNA is achieved.

FIG. 1: ASH1 mRNA transport complex. Taken from Heym & Niessing, Cell Mol Life Sci (2012).

We also study transport factors from neurons. We determined the crystal structure of the neuronal RNA-binding protein Pur-alpha and showed by SAXS that it adopts an unusual topology in solution.
Our long-term goal is to understand how core factors of large multiprotein complexes interact to (i) detect their cargo, (ii) assemble into functional complexes in response to cargo recognition and (iii) translocate their cargo through the cytoplasm. We aim to extend our understanding to transport processes in higher eukaryotes.

 

The X-ray Crystallography Plattform is also built up by our group. It is used for high-resolution structure determination of proteins and co-complexes with other proteins, nucleic acids or small inhibitory molecules.