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.
The crystal structure of a complete eukaryotic RNA Exosome complex reveals how it recognizes and processes its substrate. RNA (black) is recognized and unwound by the cap proteins (yellow, beige, orange), threaded inside the barrel (grey) and targeted to the active site of the catalytic subunit (in violet), where processive degradation occurs.
Graphics: Debora L. Makino/Copyright: MPI of Biochemistry
Scientists of the MPI of Biochemistry have now decoded the structure and the operating mechanism of the Exosome, a macromolecular machine responsible for degradation of ribonucleic acids (RNAs) in eukaryotes.One of the functions of RNAs is to permit translation of the genomic information into proteins. The results of the studies now published in Nature show that the structural architecture and the main operation mode of the Exosome are conserved in all domains of life.
“It is quite an elaborate machine: the Exosome complex forms a hollow barrel formed by nine different proteins through which RNA molecules are threaded to reach a tenth protein, the catalytic subunit that then shreds the RNA into pieces,” says Debora Makino. The barrel is essential for this process because it helps to unwind the RNA and prepares it for shredding. “Cells lacking any of the ten proteins do not survive and this shows that not only the catalytic subunit but also the entire barrel is critical for the function of the Exosome,” Makino explains.
The RNA-binding and threading mechanism used by the Exosome in eukaryotes is very similar to that of the Exosome in bacteria and archaebacteria that the researchers had structurally characterized in earlier studies. “Although the chemistry of the shredding reaction in eukaryotes is very different from that used in bacteria and archaebacteria, the channeling mechanism of the Exosome is conserved, and conceptually similar to the channeling mechanism used by the Proteasome, a complex for shredding proteins,” says Elena Conti.
In the future, the researchers want to understand how the Exosome is selectively targeted by the RNAs earmarked for degradation and how it is regulated in the different cellular compartments.
Anja Konschak | Max-Planck-Institut
A novel socio-ecological approach helps identifying suitable wolf habitats
17.02.2017 | Universität Zürich
New, ultra-flexible probes form reliable, scar-free integration with the brain
16.02.2017 | University of Texas at Austin
Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...
The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.
The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...
Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...
Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".
Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...
13.02.2017 | Event News
10.02.2017 | Event News
09.02.2017 | Event News
20.02.2017 | Materials Sciences
20.02.2017 | Health and Medicine
20.02.2017 | Health and Medicine