Stefanie Tietz

  • Mar 20, 2018

Date & Location: March 20, 2018, at 12p; Room 168 Plant Biology Building

Subject: Identification of Arabidopsis peroxisome proteins involved in photosynthesis under dynamic light conditions and in stress response under extended darkness

Abstract: Plant peroxisomes work collaboratively with other organelles, such as chloroplasts, in several metabolic processes. To investigate the impact of peroxisomal function on photosynthesis, a systematic peroxisome mutant screen with nearly 150 Arabidopsis mutants was conducted in the Dymamic Environment Phenotype Imager (DEPI) under conditions that are more relevant to the field. Dynamically changing light conditions triggered significant photosynthetic defects in a subset of the peroxisome mutants, including proteins involved in photorespiration.

Results from this study provided a basis for further dissection of the regulatory link between photosynthesis and photorespiration at the mechanistic level. To identify additional proteins with an anciliary role in photorespiration, we conducted a genetic screen to identify second-site mutations modifying the high light phenotype of the photorespiratory enzyme hydroxypyruvate reductase 1 mutant hpr1-1. So far over 30 suppressor mutants have been isolated. To discover proteins present in peroxisomes under dark stress, MS-based proteomics of peroxisomes isolated from detached Arabidopsis leaves treated with prolonged darkness was performed. This experiment detected higher number of peroxisome proteins than any of the previous proteomic analyses of plant peroxisomes, and identified the full set of peroxisomal proteins involved in ROS degradation. Novel peroxisomal proteins involved in fatty acid metabolism and stress response were also discovered.

Stefanie Tietz is a post-doc in the lab of Jianping Hu.