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The latest on ubiquitin

The Constance biologist, Prof. Marcus Groettrup, and his team of scientists are looking into proteins and their degradation processes. Christiane Pelzer and Ingrid Kassner recently discovered a previously unknown protein that plays a role in the binding of ubiquitin to target proteins. This discovery is a milestone in the research of basic enzymatic processes.

Christina Pelzer and Ingrid Kassner (Photo: University of Constance, Leitenstorfer)
During their degree and doctoral theses in the department of Professor Groettrup, Christiane Pelzer, 27, and Ingrid Kassner, 24, rather than focusing on the actual proteins themselves, focused on the degradation processes inside the cells. These degradation processes are as important as the assembly of the cells, and have, for example, an effect on specific immunological body functions. There are proteins that only survive a few minutes, others can live as long as 80 years.

Protein degradation is governed in a very sophisticated way by three enzymes with the technical names E1, E2, E3. And then there is also ubiquitin, a protein consisting of 76 amino acids that is tagged to the proteins to be degraded. These three enzymes and ubiquitin make sure that the proteins are degraded in a three-step process.

Back in the 1980s, ubiquitin was investigated in detail and the Nobel Prize in Chemistry was awarded in 2004 to Aaron Ciechanover, Avram Hershko and Irwin Rose for the discovery of ubiquitin-mediated protein degradation. “A lot of information is available about the enzyme E1 and its interactions with ubiquitin. The issue has been thoroughly investigated and can be found in any biology book published in the last 20 years. This is most likely one of the best examined biological fields. That is also why we were not looking for ubiquitin itself. We have been looking for an enzyme similar to E1 that activates a protein that looks like ubiquitin – FAT10,” said Goettrupp.
Surprisingly, Pelzer and Kassner found an enzyme that rather than activating FAT10 activated ubiquitin itself. “This discovery came as a great surprise. Deep concentration, audacity, speed – that is what was necessary to find the protein. And the two students really worked hard to reach their goal,” said Groettrup. The two young women have clearly set a new, important milestone in the discovery of basic enzymatic processes. And the findings have become known all over the world, even in the most renowned scientific journals such as “The Journal of Biological Chemistry”, where their research has now been published.

The young scientists are now investigating why the newly discovered E1 enzyme only occurs in higher organisms and which role specific E2s might play. According to Groettrup, the additional E1 provides the cell with new, additional regulatory possibilities. Highlighting the interesting E1-associated discoveries of his student, Ingrid Kassner, he said: “Ingrid tested whether E1 is expressed in all organs and tissues. She found that the protein was expressed about ten times more in the testis than in other organs. We therefore assume that this E1 has a testis-specific function.” The two young scientists now plan to develop a knock-out mouse lacking this particular enzyme. They will use the mouse to test whether mice lacking E1 can still be fertile and able to produce sperm. These investigations might eventually be able to provide answers to the basic questions of fertility.

Source: uni'kon - vol. 29/08

Publication in uni'kon: Neues zu Ubiquitin

Website address: https://www.gesundheitsindustrie-bw.de/en/article/news/the-latest-on-ubiquitin