OUR RESEARCH

Organellar Redox Signaling in Plants

ReACTs

Retrograde Arabidopsis and Chlamydomonas Thiol signaling

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Land plants and algae have to attune their physiology and morphology continuously to varying environmental challenges in order to survive and reproduce, they have evolved complex and integrated environment-cell, cell-cell, and cell-organelle signaling circuits that regulate and trigger the required adjustments (such as alteration of gene expression). Organellar signaling refers to the concept of the communication in-between organelles and with the nucleus, that entails crucial processes that govern many aspect of the multilayered response of plant cells against environmental perturbations. However, many questions remain or are feeding speculations.

What triggers retrograde signals? How are these signals transduced? What is the molecular mode of action? 

The role of ROS has greatly expanded from merely detrimental species causing distress to the view that they are crucial messengers involved in redox signaling. We know that ROS can initiate and integrate with various signaling circuits . But, it remains a long trip towards a fully-characterized ROS signaling (perceiving, transduction and function) map.  

In this project, we focus on the involvement of H2O2 in organellar redox signaling circuits.    

Post-translational modifications by H2O2 of proteins have an impact on their activity, function, localization, and stability. These PTMs might lead to adapted protein expression, which is primordial for cells and organisms to cope with changing environmental conditions. The research on transcriptional reprogramming following the chatter between chloroplasts and mitochondria is still in its in infancy, and unique to photosynthetic organisms.

Our project aims to uncover how organellar redox signals are coordinated to regulate complex plant stress responses.

We will use two model organisms: a unicellular green microalga,  Chlamydomonas reinhardtii, taken as the simplest model where chloroplast and mitochondria coexist, and Arabidopsis thaliana, which has diverged from the green microalgae long time ago towards multicellular levels and land life.

To test corresponding hypotheses, three specific objectives are defined:

• Objective 1: To investigate at the subcellular level the site-specific and quantitative sulfenylation events at an unprecedented resolution during organellar stresses in Arabidopsis and Chlamydomonas. 

• Objective 2: To understand which proteins are involved in the activation (or repression) of the transcription factors, and which protein interaction networks of transcriptional regulators are directly linked to retrograde signaling.

• Objective 3: To characterize structurally and functionally conserved (land plants and algae) redox sensors involved in organelle signaling.