Justin Findinier's Abstract

Chloroplasts and mitochondria are highly cooperative organelles in a plant cell. In the day time, carbon backbone derived from photosynthetic CO2 fixation are exported from the chloroplast to the mitochondria and participate in respiration. During the night, ATP formed by respiration in the mitochondria will be transferred to the chloroplast to sustain a number of essential functions. This crosstalk between both organelles is challenged by the presence of two physical barriers: the chloroplast envelope (composed of an inner and an outer membrane) and the mitochondrial double membrane. Several transporters allowing the passage of metabolites have already been characterized in plant cell but their number is still limiting in view of the multiplicity of molecules produced in both organelles. One of the aim of my project is to identify new transporters/translocators involved in the interfacing of chloroplasts and mitochondria by directly looking at the protein composition of the membrane through a proteomics approach.

Besides, we believe that those exchanges might be promoted by bringing the two membrane systems close together. This is for example the case in high light conditions where the mitochondria switch from a random, central distribution to a peripheral position, surrounding the chloroplast. This tight interaction might involve membrane contact site (MCS) where both the outer mitochondrial membrane and the chloroplast outer envelope membrane are anchored to each other by membrane inserted proteins. The second aim of my project is to prove that these MCS happen in Chlamydomonas reinhardtii using a fluorescence approach.

If you choose to join and help me achieving the goals of my projects, you will get familiar with basic biochemistry and molecular biology techniques such as western blot, PCR, cloning. You will also use DNA sequencing to check you did a great job. Hopefully, you will also have the opportunity to use photosynthesis measurement techniques and fluorescence imaging. Additionally to standard cloning, you will be initiated to Modular Cloning which is a new and powerful tool for manipulation of Chlamydomonas reinhardtii. Don’t hesitate to send me an email for more details.