Plant Biology Seminar

Photosynthetic electron transport has to be regulated to match the metabolic needs of the chloroplasts/cell and to reduce the level of photo-oxidative damage under excess light.  The main sites of regulation of photosynthetic electron transport will be introduced with a special focus on the redox tuning of the primary quinone acceptor QA of photosystem II and on the plastid terminal oxidase (PTOX). Photosystem II exist in different activity states with different midpoint potential of QA. Changes in the midpoint potential of QA affect charge recombination pathways within photosystem II and thereby the yield of singlet oxygen formation.
PTOX is a plastohydroquinone:oxygen oxidoreductase that belongs to the non-heme diiron carboxylate family. In plants, PTOX is important for carotenoid biosynthesis and plastid development. Its role in photosynthesis is controversially discussed. Under a number of abiotic stress conditions, the protein level of PTOX increases. PTOX is thought to act as a safety valve under abiotic stress protecting the photosynthetic apparatus against photodamage. However, transformants with high PTOX levels were reported to suffer from chronic photoinhibition. Data will be presented showing that in the transformants PTOX is highly active and competing with photosynthetic electron transport. It is proposed that PTOX activity is regulated via its subcellular localization and its pH-dependent association with the thylakoid membrane. Data will be presented showing the pH- and ion-dependency of PTOX attachment to liposomes.

Invited Speaker: Anja Krieger-Liszkay (I2BC, University Paris Saclay)
Date: Monday, October 9
Time: 4:30 pm
Place: HHU, lecture hall 6F
The PhD students will meet with the speaker after the seminar for the „PBS Lounge with Pizza and Beer" in the AG Feldbrügge seminar room (26.12.01).