The nuclear pore complex (NPC) is the gatekeeper of the nucleus that regulates the flow of all molecules across the nuclear envelope. Remarkably, this ~40 nm wide pore is capable of efficient and fast transport while remaining highly selective. Its dense central channel is composed of a highly dynamic spaghetti-like mesh of intrinsically disordered proteins that allows small molecules to pass freely, whereas large macromolecules (>40 kDa) rely on specific transporter proteins that ferry their cargo across the pore. This process is vital to the well-being of the cell, as the NPC poses a gate between the nucleus, the place of the genetic material and mRNA transcription, and the cytosol, where proteins are synthesized from mRNA by ribosomes - hence posing a bottleneck for the central dogma of molecular biology by regulating the flow of mRNA. At the same time, the NPC protects the genetic material from viral intruders, but needs to allow efficient import of proteins to the nucleus to maintain the structural integrity of the genome, and perform and regulate gene transcription. Given its vital importance, it is unsurprising that mutations of the NPC have been linked to numerous neurodegenerative diseases and various forms of cancer.
Even though various models have been proposed, the fundamental biophysical mechanism of nuclear transport and of the selectivity of the NPC has not been resolved yet. One of the main reasons that have hindered our progress in understanding nuclear transport is the lack of experimental techniques that can probe the structure and dynamics of the disordered proteins and transport receptors inside the NPC channel and during transport with sufficient spatiotemporal resolution. In this project, we have combined nanotechnology with single-molecule fluorescence microscopy to build and study biomimetic, minimal versions of the NPC.
