'Fuzzy' interaction makes it possible for the nuclear pore complex to rapidly and selectively move large molecules
A cell does everything it can to protect its nucleus, where precious genetic information is stored. That includes controlling the movement of molecules in and out using gateways called nuclear pore complexes (NPCs).
Because it lacks a predictable structure, an FG Nup (green), a component of the nuclear pore complex, can interact quickly with a transport factor (purple) bound to large cargo. This interaction makes selective and rapid transport into and out of the nucleus possible.
Credit: Laboratory of Cellular and Structural Biology at The Rockefeller University
Now, researchers at The Rockefeller University, Albert Einstein College of Medicine, and the New York Structural Biology Center have identified the molecular mechanism that makes both swift and cargo-specific passage through the NPC possible for large molecules. Their work appeared September 15 in eLife.
Scientists are paying close attention to this regulation since dysfunction in nuclear transport has been linked to many diseases, including cancers and developmental disorders.
While small molecules can easily pass in and out of the nucleus, the transport of large molecules such as proteins and RNA is more complex and less well understood. These are moved through the NPC rapidly, but also selectively to avoid allowing the wrong big molecules through.
It was already known that proteins called transport factors bind to large cargo and escort it through the NPC. A team led by Michael P. Rout, a professor at Rockefeller University and head of the Laboratory of Cellular and Structural Biology, and David Cowburn, a professor of biochemistry and of physiology & biophysics at Albert Einstein College of Medicine, sought to explain the speed with which transport factors ferry large molecules across the NPC, a process that lasts only a few milliseconds.
"It's understood how these transport factors selectively choose and bind to their cargo," Rout says. "However, it's been unclear how such a specific process can also shepherd molecules through the nuclear pore complex so quickly."
At the center of the NPC, the transport factors and their cargo must pass through a selectivity filter made of proteins called FG Nups. These proteins form a dense mesh that normally prevents large molecules from getting through. Using a technique known as nuclear magnetic resonance spectroscopy, the researchers collected atomic-scale information about the behavior of the FG Nups, focusing on Nsp1, the most studied representative of the FG Nups.
Normally, proteins fold into large structures. Relative to small molecules such as water, these large protein structures move very slowly. This means their interactions are correspondingly slow.
The researchers measured the physical state of FG repeats with and without transport factors bound to them. They found that rather than folding like proteins generally do, the FG Nups are loose and string-like, remaining highly dynamic and lacking a predictable structure.
"Usually, binding between traditionally folded proteins is a time consuming, cumbersome process, but because the FG Nups are unfolded, they are moving very quickly, very much like small molecules. This means their interaction is very quick," explains Rout.
The disordered structure of the FG regions is critical to the speed of transport, allowing for quick loading and unloading of cargo-carrying transport factors. At the same time, because transport factors have multiple binding sites for FG Nups, they are the only proteins that can specifically interact with them -- making transport both fast and specific.
"We observed that there is minimal creation of a static well-ordered structure in complexes of FG Nups and transport factors," says Cowburn. "Our observations are, we propose, the first case where the 'fuzzy' property of an interaction is a key part of its actual biological function."
The team hopes this discovery will lead to detailed characterizations of nuclear transport pathways and to more close studies of the NPC's function. Ultimately, a better understanding of how the NPC works will not only provide new insight into the basic biology of cells, but also have implications for health and disease.
Wynne Parry | EurekAlert!
First time-lapse footage of cell activity during limb regeneration
25.10.2016 | eLife
Phenotype at the push of a button
25.10.2016 | Institut für Pflanzenbiochemie
Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.
This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...
Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion
Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...
Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.
"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...
In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.
A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...
By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.
"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...
14.10.2016 | Event News
14.10.2016 | Event News
12.10.2016 | Event News
25.10.2016 | Earth Sciences
25.10.2016 | Power and Electrical Engineering
25.10.2016 | Process Engineering