Time: 10.30hrs

Location: Kronigzaal

Export of Single mRNAs through Nuclear Pores in Living Cells.

Molecular interactions, key to many biological functions, occur within the living cell under specific environmental conditions. Parameters such as accessibility, interaction times and binding sites are poorly understood for most known biochemical reactions in cells. Observation of single molecules in living cells, however, would provide a unique tool to enhance our understanding of the complex molecular biology. Compartmentalization, the separation of genetic information in the nucleus, has been identified as key concepts in the design of eukaryotic cells. A direct consequence thereof is the need of cellular transport and sorting mechanisms. Diffusion combined with microenvironments might be such a mechanism. A prominent example of such a process is the transport across the nuclear membrane. Matter, energy and information need to be transported between the nucleus and the cell body. The nuclear pore complexes (NPC) are the sole transporter between cytoplasm and nucleus in the eukaryotic cell. They are large nano-machines with diameters of roughly 120 nm. By tracking single proteins, transport factors and mRNAs, we investigated the function of nucleocytoplasmic transport. These measurements allowed defining the interaction sites within the nuclear pore complexes with unprecedented precision, and revealed distinct differences between protein import and mRNA export. Combination of unique labeling and microscopy tools provided spatially resolved kinetic rates for a three step model of mRNA export, consisting of docking, transport and release, totaling 180±10 ms.