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Biophysical properties of the transport barrier in the nuclear pore complex

Bestembayeva, A; (2016) Biophysical properties of the transport barrier in the nuclear pore complex. Doctoral thesis , UCL (University College London). Green open access

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Abstract

The Nuclear Pore Complex (NPC) is a large protein structure found in eukaryotic cells, perforating the nuclear envelope. It mediates bidirectional selective transport between the nucleus and the cytoplasm. The NPC contains a permeability barrier consisting of unstructured nuclear pore proteins. The structure of the permeability barrier is not well defined. As a consequence, various models have been proposed for its structure and functionality. Typically, these models consider the unstructured nuclear pore proteins as weakly or strongly interacting polymers: In the first case nuclear pore proteins protrude from the pore creating an entropic barrier; in the second case they may form a meshwork occupying the central channel, resembling a hydrogel. In this thesis, I measure the nanomechanical properties of this barrier in intact NPCs, and compare them to the properties expected for entropic brushes and gel-like materials. To this end, I carried out nanometre-scale force spectroscopy measurements using Atomic Force Microscopy (AFM). Prior to the measurements the pores were treated with reagents that activated the transport process, thus flushing out the pores to ensure that I was probing the barrier itself instead of cargo stuck in transit. I carried out Laser Scanning Confocal Microscopy experiments to verify this procedure, as well as to measure transport properties of the pores in isolated nuclei. For comparison, I also measure nanomechanical properties of artificial polymer brushes, and set the first steps towards creating protein-coated solid-state nanopores as a reductionist model system for the NPC. My results indicate that the proteins in the NPC form a condensed network, more closely resembling a hydrogel than a brush dominated by entropic interactions.

Type: Thesis (Doctoral)
Title: Biophysical properties of the transport barrier in the nuclear pore complex
Event: University College London
Open access status: An open access version is available from UCL Discovery
Language: English
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
URI: http://discovery.ucl.ac.uk/id/eprint/1474430
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