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
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences