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uni'wissen 01-2014_ENG

Dr. Marco Chiabudini studied biochemistry and molecular medicine in Regensburg and Freiburg. He has been a member of Prof. Dr. Sabine Rospert’s research team at the Institute of Biochemistry and Molecular Biology in Freiburg since 2007. After completing his doctorate in 2012, he began researching there as a post- doc. His main research interest is the interaction of the translational machinery with the cellular quality control mechanisms for messenger ribonucleic acids and proteins in the baker’s yeast Saccharomyces cerevisiae. Photo: Patrick Seeger Further Reading Chiabudini, M. / Conz, C. / Reckmann, F. / Rospert, S. (2012): RAC / Ssb is required for translational repression induced by polylysine segments within nascent chains. In: Molecular and Cellular Biology 32 / 23, pp. 4769–4779. Karamyshev, A. L. / Patrick, A. E. / Karamysheva, Z. N. / ,Griesemer, D. S. / Hudson, H. / Tjon-Kon-Sang, S. / Nilsson, I. / Otto, H. / Liu, Q. /  Rospert, S. / Heijne, G. / Johnson, A. E. / Thomas, P. J. (2014): Inefficient SRP interaction with a nascent chain triggers a mRNA quality control pathway. In: Cell 156 / 1–2, pp. 146–157. “The production of potentially toxic proteins is reduced to a minimum.” Prof. Dr. Sabine Rospert studied biology and chemistry in Marburg and earned her PhD in microbiology in 1991. She then worked as a post- doc and an independent research assistant at the Biozentrum of the University of Basel, Switzerland, where she completed her habilitation in biochemistry. In 1999 she became a junior research group leader at the Max Planck Research Unit for Enzymology of Protein Folding in Halle/Saale. Since 2003 she has served as director of the Department of Biochemistry II at the Institute of Biochemistry and Molecular Biology of the University of Freiburg’s Faculty of Medicine. She is a member of the Cluster of Excellence BIOSS Centre for Biological Signalling Studies and the collaborative research center SFB 746, “Functional Speci- ficity by Coupling and Modifi- cation of Proteins.” She conducts research on the molecular effect of ribosome- associated protein biogenesis factors on newly synthesized polypeptide chains in eukaryotic cells. Photo: private factor is responsible for this type of regulation. Instead of the known signal recognition particle SRP, a particle by the name of Ago2 from the group of argonaute proteins binds to the ribosome and the chain with the mutations. Ago2 succeeds in establishing a link to the mRNA and initiates the process of breaking down the defective mRNA. “The production of potentially toxic proteins is reduced to a minimum,” explains Rospert. Advantage for the Cell This in turn has a positive influence on the cell’s energy balance, because it no longer has to produce or break down defective proteins. “It is not yet known precisely how the mRNA is broken down upon contact with Ago2,” explains Chiabudini. One possibility is that it uses a nuclease, an enzyme specialized in cleaving mRNA molecules. “We are increasingly certain that the mRNA quality control is linked to the control at the protein level,” says Rospert. The researchers have understood that the cell replaces the “cookie cutter” to prevent the production of defective proteins. Now they want to find out how this happens – and achieve further insight into what is likely a fundamental mechanism cells use to protect themselves against damage from defective and misplaced proteins. 35