High light stress in photosynthesis:the role of oxidative post-translational modifications in signaling and repair

Tryptophan;Reactive oxygen species;Photosynthesis;Photosystem II;N-formylkynurenine;Synechocystis 6803

Kasson, Tina Michelle Dreaden ; Chemistry and Biochemistry

University:Georgia Institute of Technology

Department:Chemistry and Biochemistry

关键词: Tryptophan;    Reactive oxygen species;    Photosynthesis;    Photosystem II;    N-formylkynurenine;    Synechocystis 6803;   

Others  :  https://smartech.gatech.edu/bitstream/1853/45759/1/DreadenKasson_Tina_M_201212.pdf

美国|英语

来源: SMARTech Repository

【 摘 要 】

Oxidative stress is a natural consequence of photosynthetic oxygen evolution and redox enzyme processes. Trp oxidation to N-formylkynurenine (NFK) is a specific, reactive oxygen species (ROS)-mediated reaction. This thesis work describes the identification and functional characterization of NFK in oxygen evolving Photosystem II (PSII). Although proteomics studies have confirmed NFK modifications in many types of proteins, limited knowledge on the biochemical significance exists. In vitro studies in thylakoids and PSII membranes were used to establish a correlation between oxidative stress, NFK formation, and photoinhibition. The in vivo effect of preventing Trp oxidation to NFK was assessed by site-directed mutation in the cyanobacteria Synechocystis sp. PCC 6803. This work provides insight into the role of NFK in photosynthetic oxygen evolution and photoinhibition. Based on the current knowledge of NFK, ROS, and repair, a new model is described. In this modified model for photoinhibition and repair, NFK plays a role in signaling for turnover of damaged proteins. NFK may play a similar role in replacement of damaged proteins in other systems.