Gatsogiannis Group - cryoEM of Complex Nanosystems
We are an international team of biologists, biochemists and physicists led by Prof. Dr. Christos Gatsogiannis, dedicated to elucidating the architecture of complex nanomachines by their direct visualization using cryo-EM. This technique allows us to directly visualize biological samples such as proteins, viruses and large macromolecular complexes down to atomic resolution, purified or even in their functional cellular environment. Combined with biochemical, biophysical, molecular biology, and bioinformatics methods, we can provide crucial mechanistic insights, providing a solid framework for understanding their mode of action.
Our research focuses on molecular understanding of peroxisomal biogenesis, its import machinery and associated signaling pathways. We also focus on molecular understanding of the mechanisms of pore-forming neurotoxins and AAA-ATPases, which play key roles in protein quality control. Multidisciplinary research, strong synergies and state-of-the-art infrastructure are required to answer our complex and multifaceted central questions.
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On a journey to an unknown country
Prof. Christos Gatsogiannis from the Institute of Medical Physics and Biophysics is responsible for cryo-electron microscopy at the University of Münster. April 2023 saw the inauguration in his working group of a piece of very high-performance equipment.
As Christos Gatsogiannis is packing his bags in his hometown of Karditsa, in Greece, before setting off to study in Germany – instead of Athens, like his friends – he is 18 years old. He has long wondered about whether it is the right decision – but everything falls into place very quickly: in Germany, his doubts are dispelled as soon as he has embarked on his language course at the Goethe Institute in Frankfurt. Please find here the whole portrait.
The "Paper of the Month" 09/2023 goes to: Maximilian Rüttermann and Christos Gatsogiannis from the Institute of Medical Physics and Biophysics
Structure of the peroxisomal Pex1/Pex6 ATPase complex bound to a substrate
Background and fundamental question of the publication:
Peroxisomes are cell organelles that are critical for a variety of metabolic functions. Defects in peroxisomal biogenesis lead to devastating metabolic and developmental disorders known as peroxisomal biogenesis disorders (PBD) or Zellweger syndrome, which are associated with a mechanistic defect in the peroxisomal Pex1/Pex6-ATPase complex in up to 65 % of cases.
The Pex1/Pex6 complex is the driving force for the import of enzymes into peroxisomes through the recycling of import receptors from the peroxisome membrane. Biochemical and structural techniques were used to elucidate the mechanism of this highly complex molecular machine. Using cryoEM, the three-dimensional structure of Pex1/Pex6 was elucidated in different states. Thus, it could be shown for the first time in near-atomic resolution how the ATPases Pex1 and Pex6 associate to form a hexamer complex and work synchronously. In this process, ATP is converted into mechanical forces to extract peptides from the peroxisome membrane. The mechanism is unique, comparable to a row of arms which, step by step, pull a thick rope in pairs and, in the process, until its knots.
Unlike other AAA-ATPases, Pex1 and Pex6 act together in dimers during ATP hydrolysis. This previously unknown mechanism allows us to understand mutations associated with Zellweger syndrome at the molecular level, which may help in the future development of therapeutic approaches.
Eda Samiloglu Tengirsek receives a scholarship from the German National Academic Foundation
Gatsogiannis Laboratory student Eda Samiloglu Tengirsek has been selected by the German Academic Scholarship Foundation to receive a prestigious doctoral scholarship in the field of structural biology. The Studienstiftung des deutschen Volkes promotes "the university education of young people who can be expected to make an outstanding contribution to society as a whole due to their exceptional scientific or artistic talent and personal qualities".
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