Reference : PhD Bruno Klaholz
The ribosome is a molecular machinery that goes through different phases, notably initiation, elongation and termination of messenger RNA translation. Protein synthesis is catalyzed by the ribosome and is regulated by protein factors that bind transiently to the ribosome during the different phases. Over the last years, the three-dimensional structures of various bacterial and some eukaryotic ribosomes have been determined, either by X-ray crystallography or by cryo electron microscopy (cryo-EM).
Very recently, our research group succeeded in purifying the human ribosome to high homogeneity and determined its three-dimensional structure to ~3 Å resolution using cryo-EM (Khatter et al., Nature 2015; Natchiar et al., Nature 2017) which represents a major scientific and technical challenge. The structure provides unprecedented insights into the detailed architecture of the human ribosome down to the visualization of side-chain positions and conformations of ribosomal RNAs and proteins.
This opens unique possibilities in studying the molecular mechanisms of protein synthesis in humans. Two key questions are arising now and will be addressed during the studies conducted as part of this PhD project: (i) what is the molecular basis of specificity of interactions of ligands such as antibiotics that would allow distinguishing the bacterial target from the human target which can be a source of side-effects during anti-infectious treatments, and (ii) what are the regulatory mechanisms of protein factors binding to the human ribosome. The study will comprise the biochemical preparation of the ribosome and of factors, the reconstitution and biophysical characterization of the human ribosome complexes and the determination of the atomic structure using cutting-edge technologies (on-site high-resolution cryo electron microscopy, single particle image processing and 3D reconstruction, atomic model refinement using structure refinement methods used in crystallography, as established and described in the publications Khatter et al., Nature 2015 and Natchiar et al., Nature 2017).
This project will allow a better understanding of the function of the human ribosome and will have important implications for the development of antibiotics. The project will benefit from the technological platforms in Structural Biology and Genomics available as part of the infrastructures hosted at the new Centre for Integrative Biology at the IGBMC.
Wished skills (maximum 600 caractères, espaces et sauts de lignes compris) :
Since the project has a strong interdisciplinary character (integrative structural biology approach), we can welcome a student having either type of Master, including biochemistry, molecular biology, bioinformatics, chemistry, physics or mathematics, as long as the candidate is open-minded for learning new technologies.
Expertises which will be acquired during the training (maximum 600 caractères, espaces et sauts de lignes compris):
Training will be provided in biochemistry and biophysical characterisation of macromolecular complexes, in image data collection using a novel high-resolution electron microscope recently installed, training in image processing, structure determination and atomic model building and refinement using tools from crystallography, integration of functional data.
Application Deadline : Nov. 1, 2018