Macromolecules in Motion by High-resolution Cryo-EM

by Valentyn Petrychenko
Doctoral thesis
Date of Examination:2023-05-08
Date of issue:2024-05-06
Advisor:Dr. Niels Fischer
Referee:Prof. Dr. Kai Tittmann
Referee:Prof. Dr. Marina Rodnina
Referee:Prof. Dr. Holger Stark
Referee:Prof. Dr. Helmut Grubmüller
Referee:Dr. Alex Faesen
Persistent Address: http://dx.doi.org/10.53846/goediss-10483

 

 

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Abstract

English

Protein synthesis, the translation of the genetic code into a defined sequence of amino acids, is a central, highly dynamic and regulated step in gene expression. The well-defined bacterial translation system enables to study the fundamental principles of how large macromolecular machines, such as the ribosome, perform their work in the cell. In addition, the prokaryotic ribosome is the major cellular target for antibiotics, and studies of functional ribosome-antibiotic complexes promise new insights into antibiotic action and how to overcome the rise in drug-resistant pathogens. In contrast to the bacterial system, human translation is much more complex. Particularly the initiation step in humans is highly regulated and dysregulation of initiation has been implicated in various diseases, such as cancer. The study of translation initiation therefore provides crucial insights into regulation of human gene expression and may provide new avenues to interfere with disease. Understanding the bacterial ribosome at work requires visualizing highly transient states, whereas mammalian translation initiation complexes are very fragile multi-subunit RNA-protein machineries, posing a general challenge for structural biology. In the present work, I have used cryo-EM guided by rapid kinetics to visualize key translation pathways including critical and fragile structural intermediates to understand the underlying mechanisms of translation in bacteria and humans.
Keywords: Cryo-EM; Translation; Initiation; Elongation; Translocation; Rescue; Ribosome; 43S PIC; 48S IC; Bacteria; Human