Origins of the Eukaryotic Endomembrane System

Origins of the Eukaryotic Endomembrane System

By In Aiv Internship On April 8, 2019

Internship title: Origins of the Eukaryotic Endomembrane System

Name: Membrane Dynamics and Intracellular Trafficking
Affiliation: Institut Jacques Monod, CNRS – University of Paris
Address: Bat. Buffon – P. 144B, 15 rue Hélène Brion, 75205 Paris Cedex 13 France

LAB Director
Name: Catherine L. Jackson and Jean-Marc Verbavatz
Phone number: +33-157278004

Name: Catherine Jackson
Phone number: +33-157278004

Subject Keywords: Cellular Membranes, Organelle, Eukaryogenesis, Arf small G proteins, Asgard archaea
Tools and methodologies: Molecular biology, light microscopy, microbiology, GTPase activity assays
Summary of lab’s interests: Eukaryotic cells are characterized by their internal membrane compartments (organelles). This endomembrane system assures the accurate targeting of intracellular material as well as the uptake and export of material at the cell surface. In humans, this process enables neurotransmission, hormone secretion, and when dysregulated results in human pathologies such as cancer, diabetes, obesity and neurodegenerative diseases. The Arf family of small G proteins (GTPases) are crucial regulators of the structure and function of the endomembrane system. Our group identified the Sec7 domain Arf activators and has studied their functions, as well as discovering novel functions of Arfs and their regulators.

Project summary: The project will address the deep cellular evolution of the eukaryotic Arf family of GTPases, providing new insights into eukaryogenesis. The emergence of eukaryotic cells from their prokaryotic ancestors is one of the most significant events in the history of life. But how eukaryotes arose, although hotly debated, remains mysterious. The predominant view postulates that eukaryotes originated from an archaeal lineage that entered into symbiosis with the bacterial ancestor of mitochondria. The archaeal host lineage contributed many of the building blocks for eukaryotic organelles.

In an exciting recent development, Arf-related proteins have been identified in newly discovered archaea lineages (the Asgards), suggesting that these proteins were present in the common ancestor of archaea and eukaryotes. The project will consist of first identifying candidate Arf-related proteins in Asgard archaea using bioinformatics approaches. The second objective is to use functional assays (cell biological and biochemical) to determine whether candidates identified in silico have Arf GTPase functions. The Asgard Arf-related protein candidates will be expressed, using synthetic gene technology, in eukaryotic cells and in bacteria. Expression in yeast and mammalian cells will allow cell biological characterization, and proteins purified from bacteria will be tested in biochemical assays of Arf GTPase function.

Interdisciplinary aspect of the project: This project will combine bioinformatic, cell biological, biochemical and structural biology approaches to determine whether Asgard archaeal predicted proteins possess Arf family GTPase function. The project relies first on metagenomics, phylogenomics and phylogenetics approaches to identify Arf-related proteins in existing and new Asgard archaea species, in collaboration with the groups of Joel Dacks (University of Alberta, Canada) and Thijs Ettema (Wageningen University, the Netherlands). Cell biological and biochemical analyses will be carried out in our lab, and we will collaborate with the group of Julie Ménétrey (I2BC, CNRS/CEA/Université Paris-Sud, France) to carry out structural analyses of Asgard Arf-related proteins.