Much in the same way as we use shredders to destroy documents that are no longer useful or that contain potentially damaging information, cells use molecular machines to degrade unwanted or defective macromolecules.
Scientists of the Max Planck Institute of Biochemistry (MPIB) in Martinsried have now shown how the nuclear compartment of the cell uses a specific version of the RNA exosome, a macromolecular machine responsible for the degradation as well as the biogenesis of ribonucleic acids (RNAs). RNAs are ubiquitous and abundant molecules with multiple functions in the cell. One of their functions is, for example, to permit translation of the genomic information into proteins.
Any errors that occur during the synthesis of RNA molecules or unwanted accumulation of RNAs can be damaging to the cell. The elimination of defective RNAs or of RNAs that are no longer needed are therefore key steps in the metabolism of a cell.
The exosome, a multi-protein complex, is a key machine that shreds RNA into pieces. In addition, the exosome also processes certain RNA molecules into their mature form. In a study two years ago, scientists in the Research Department ‘Structural Cell Biology’ headed by Elena Conti unveiled the X-ray structure of the exosome core complex. The multi-protein complex consists of nine proteins that form a central substrate channel that ends in the protein Rrp44, the exosome RNA degrading center.
Specific shredders for each compartment of the cell
Different cellular compartments, such as the nucleus or the cytoplasm, have their own specific versions of a larger exosome complex bound to specific helper proteins. The MPIB scientists could now reveal how the exosome in the nucleus works together with two protein-subunits called Rrp6 and Rrp47, which are specific only for RNA substrates of the nucleus.
“We could show that the cell has multiple possible paths of degrading nuclear RNA,” explains Debora Makino, one of the authors of the study. One of the pathways leads the RNA substrate into direct degradation by Rrp6 and/or Rrp44, and the other guides the RNA into the processive degradation by Rrp44 via the core RNA exosome channel path. “In this manner, the cell can degrade RNA substrates either completely or trim them precisely when needed,” says Benjamin Schuch, the other author of the study.
Future research will uncover further RNA processing mechanisms involving the core exosome and its various auxiliary proteins, protein complexes, and RNA substrates located throughout all cell compartments.
D.L. Makino*, B. Schuch*, E. Stegmann, M. Baumgärtner, C. Basquin and E. Conti: RNA degradation paths in a 12-subunit nuclear exosome complex. Nature, July 29, 2015
http://www.biochem.mpg.de/5092413/20150731_conti_exosome - Detailed Press Release
http://www.biochem.mpg.de/conti - Website of the Research Department 'Structural Cell Biology' (Elena Conti)
Anja Konschak | Max-Planck-Institut für Biochemie
Multi-institutional collaboration uncovers how molecular machines assemble
02.12.2016 | Salk Institute
Fertilized egg cells trigger and monitor loss of sperm’s epigenetic memory
02.12.2016 | IMBA - Institut für Molekulare Biotechnologie der Österreichischen Akademie der Wissenschaften GmbH
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
02.12.2016 | Medical Engineering
02.12.2016 | Agricultural and Forestry Science
02.12.2016 | Physics and Astronomy