Photo-oxidative stress response in Chlamydomonas: Regulation of singlet oxygen acclimation through dynamic changes in intracellular phosphorylation and extracellular signaling
EMSL Project ID
50491
Abstract
Growth of photosynthetic organisms depends on light energy, which in excess causes oxidative damage if not managed properly. Singlet oxygen (1O2) is a highly toxic form of ROS that is predominantly generated at the reaction center of photosystem II under excess light and is a central component of photo-oxidative stress response in plants. Suboptimal adaptation of photosynthesis and inefficient response to photo-oxidative stress leads to decrease in primary productivity. A better understanding of the underlying molecular mechanisms in how cells respond to dynamic light conditions and photo-oxidative stress brings us closer to achieving the reengineering of plants and algae to increase stress tolerance and thus productivity. Wildtype Chlamydomonas is uniquely capable of acclimating to 1O2: an exposure to sub-lethal level of 1O2 elicits nuclear gene expression changes, which in turn lead to increased resistance to a subsequent exposure to 1O2, while the mutant sak1 (singlet oyxgen acclimation knocked-out 1) is disrupted in this response. SAK1 is a cytosolic phosphoprotein that regulates acclimation, and its absence disrupts the acquisition of enhanced resistance and the induction of the most strongly up-regulated genes during exposure to sub-lethal levels of 1O2. We have recently found that wildtype Chlamydomonas cells but not those of sak1 excrete a signaling molecule into the medium during 1O2 acclimation, and that this signal is sufficient to convey 1O2 resistance to naive cells. Our objective in the current work is to identify this signaling molecule by surveying the media for secreted compounds from Chlamydomonas cells and to examine the dynamic changes in phosphorylation of intracellular proteins during 1O2 acclimation. The state-of-the-art EMSL resource in mass spectrometry will make it possible to detect compounds in the medium that are at low abundance to obtain a more comprehensive view, as well as high-resolution phosphorylation patterns and its dynamic changes during 1O2 acclimation within Chlamydomonas cells. This will be combined with our strength of having isolated multiple mutants affected in this pathway. The dataset obtained from this study will be a resource to further search for signaling components, focusing on phosphorelay that is critical in responding to 1O2. By examining the breadth of secreted compounds, we will search for novel ways with which Chlamydomonas cells may communicate with each other and with other organisms in its environment, a research field which we still have yet to break ground.
Project Details
Project type
Exploratory Research
Start Date
2018-10-21
End Date
2020-01-31
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members