In order to protect themselves from harmful substances, cells need to keep the mitochondria – the boiler room, so to speak – shipshape. Up to now, it was unclear whether this housekeeping work involves sorting out defective proteins when they digest mitochondria.
Yeast cells digest their mitochondria in long-time cultures. This process is called mitophagy. Proteins that are digested at a different speed are marked with a fluorescent dye. (© Joern Dengjel)
Dr. Joern Dengjel from the Center for Biological Systems Analysis (ZBSA), Freiburg Institute for Advanced Studies (FRIAS), and the Cluster of Excellence BIOSS Centre for Biological Signalling Studies of the University of Freiburg has now discovered in collaboration with researchers from the Hebrew University in Jerusalem, Israel, that the proteins are sorted out during the constant fusion and fission of mitochondria. The team published their findings in the journal Nature Communications.
The process of mitophagy, in which tiny digestive bubbles surround the mitochondria, serves to recycle waste for the cell. Damaged proteins can no longer carry out their function correctly and need to be broken down. Errors in the digestion of mitochondria appear in old age and in the case of neurodegenerative diseases like Parkinson’s and Alzheimer’s. A better understanding of mitophagy could be the key to counteracting the faulty degradation of cellular components, potentially enabling researchers to develop new therapies for neurodegenerative diseases.
In contrast to bacteria, yeast cells posses mitochondria and are also easy to grow in the laboratory. The researchers used yeasts to observe the processes of mitophagy. Dr. Hagai Abeliovich from the Hebrew University developed a new method for making yeast cells digest mitochondria. Currently, researchers accomplish this by placing stress on the cells with chemicals.
With the new method, yeast cells in long-term cultures begin digesting mitochondria of their own accord – as soon as they have used up all available nutrients. During mitophagy Dengjel succeeded in measuring whether all proteins inside the mitochondria were broken down at the same speed. Indeed, the cell broke down some proteins more quickly than others. When he observed the cells under a fluorescence microscope, he ascertained that the marked proteins in the mitochondria also behaved differently. They appear to be sorted.
The rules by which the sorting is carried out are as yet unknown. However, the researchers demonstrated that mitochondrial dynamics are involved: Mitochondria fuse and divide constantly, forming a network in the process. Genetically modified yeasts that lack these dynamics but form small, round mitochondria exhibit no sorting of the proteins. “The damaged proteins are sorted slowly into an area of the network with each fusion and fission. This mitochondrion is marked and broken down,” says Dengjel. In other words, mitophagy plays the role of garbage collector, separating and recycling waste for the cell. Now Dengjel wants to find out what characterizes the proteins that are sorted out.
Dr. Jörn Dengjel | Universität Freiburg
Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides
16.07.2018 | Tokyo Institute of Technology
The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology
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....
Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.
Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
16.07.2018 | Physics and Astronomy
16.07.2018 | Life Sciences
16.07.2018 | Earth Sciences