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Home > Departments > Cell Biology > Sébastien THOMINE : Integrated Approches to Ion Transport

Sébastien THOMINE : Group Presentation

General presentation

In living organisms, ions can be nutrients, osmoticum, signalling molecules or toxic elements. Therefore, ion transport across biological membranes plays a fundamental role in the regulation of cell homeostasis and also for interaction with other cells and the environment. Plants are non-motile organisms that have to face large variations of their local environment (nutrient availability, toxic element, mechanical stresses) along their life cycle. Plants therefore represent a good model to integrate the study of ion transport from cell homeostasis to the interaction with their environment.
Plant cells display specificities for ion transport and compartmentalisation. The presence of the cell wall imposes specific mechanical constraints on the plasma membrane. In most cells, the vacuole occupies around 80% of the cell volume and is essential for nutrient storage, sequestration of toxic compounds and the regulation of cytosolic parameters (e.g. pH). In photosynthetic cells, chloroplasts represent the main source of metabolic energy and use most of cellular iron.
Our team is internationally recognized for its expertise on ion transport in plants (Thomine & Barbier-Brygoo 2010, Barbier-Brygoo et al. 2011) and relies on a strong network of national and international collaborations. Our specificity is to start from mechanisms and functions of transporter families and integrate their activity in the context of the whole cell, the organism and its interaction with the environment.
Our team investigates families of ion transporters/channels involved in anion transport, metal transport, metal hyperaccumulation and mechanosensitivity, respectively, sharing a common strategy and common approaches. This approach led to original findings on transport mechanisms (Wege et al., 2010), connections between nutrition and responses to environmental stresses (Wege et al., 2014) and the discovery of the molecular basis for mechanosensitive ion channel activity in plant cells (Haswell et al., 2008).
We believe that a complete characterization of ion transport systems addressing their ion selectivity, their transport mechanism and their regulation at the molecular level is necessary to understand their integrated function. Our first objective is thus to expand our expertise in functional expression of membrane proteins and electrophysiology to characterize new ion transporters and their regulations.
We seek to integrate the molecular knowledge on transporters in a cellular framework. This requires access to the parameters that govern the transporter activity as well as a precise knowledge of the cell types and the environmental conditions controlling transporter expression. Our second objective is (i) to develop a tool box to monitor relevant cellular parameters such as ion concentrations, membrane potential or membrane tension, (ii) to integrate transporter activities in cell specific functions and signalling networks.
Finally, we are convinced that New Generation Sequencing (NGS) technologies will considerably speed-up the identification of new players in plant ionic homeostasis. Our third objective is to identify novel genes involved in metal homeostasis either through genetic screens in Arabidopsis thaliana or through transcriptomic comparisons between metal hyperaccumulators species.

Keywords

Ion channel, transporter, plant, metal, mechanoperception, signaling, homeostasis, environment

Contact


THOMINE Sébastien [Senior Researcher - CNRS]
Integrated Ion Transport [Leader]
01 69 82 46 32 Gif - Bât 21

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