UNIVERSITY OF BASELUsing ultra fast-scanning atomic force microscopy (AFM), scientists have filmed nuclear pore complexes in action for the first time. The work reveals how these structures selectively bar some substances from entering the nucleus, researchers at the University of Basel, Switzerland, reported today (May 2) in Nature Nanotechnology.
“With the high-speed AFM we could, for the first time, peer inside native nuclear pore complexes only forty nanometers in size,” study coauthor Roderick Lim of the University of Basel said in a statement. “This method is a real game changer.”
Nuclear pores consist of a central transport channel surrounded by intrinsically disordered proteins called nucleoporins. Lim and his colleagues used high-speed AFM to visualize the behavior of phenylalanine-glycine nucleoporins (FG Nups) inside the nuclei of African clawed frog (Xenopus laevis) cells at a resolution of about 100 milliseconds. To access the nuclear pore at such high resolution, the researchers had to grow ultra-sharp carbon nanofibers on the AFM probes.
AFM imaging revealed how the FG Nups rapidly expand and contract, like tentacles, to form a kind of mesh across the nuclear opening. Large molecules move more slowly than these pore proteins and are blocked from entering the nucleus, whereas small molecules move more quickly and have a much better chance of getting in, the researchers explained in their paper.
Lim’s team is now investigating how to make nuclear pore-inspired filters for nonbiological systems, according to the statement.