scholarly journals The Dual Role of the Plastid Terminal Oxidase PTOX: Between a Protective and a Pro-oxidant Function

2016 ◽  
Vol 6 ◽  
Author(s):  
Anja Krieger-Liszkay ◽  
Kathleen Feilke
2007 ◽  
Vol 145 (3) ◽  
pp. 691-702 ◽  
Author(s):  
Maryam Shahbazi ◽  
Matthias Gilbert ◽  
Anne-Marie Labouré ◽  
Marcel Kuntz

2017 ◽  
Vol 372 (1730) ◽  
pp. 20160379 ◽  
Author(s):  
Kathleen Feilke ◽  
Ghada Ajlani ◽  
Anja Krieger-Liszkay

Cyanobacteria are the most ancient organisms performing oxygenic photosynthesis, and they are the ancestors of plant plastids. All plastids contain the plastid terminal oxidase (PTOX), while only certain cyanobacteria contain PTOX. Many putative functions have been discussed for PTOX in higher plants including a photoprotective role during abiotic stresses like high light, salinity and extreme temperatures. Since PTOX oxidizes PQH 2 and reduces oxygen to water, it is thought to protect against photo-oxidative damage by removing excess electrons from the plastoquinone (PQ) pool. To investigate the role of PTOX we overexpressed rice PTOX fused to the maltose-binding protein (MBP-OsPTOX) in Synechocystis sp. PCC 6803, a model cyanobacterium that does not encode PTOX. The fusion was highly expressed and OsPTOX was active, as shown by chlorophyll fluorescence and P 700 absorption measurements. The presence of PTOX led to a highly oxidized state of the NAD(P)H/NAD(P) + pool, as detected by NAD(P)H fluorescence. Moreover, in the PTOX overexpressor the electron transport capacity of PSI relative to PSII was higher, indicating an alteration of the photosystem I (PSI) to photosystem II (PSII) stoichiometry. We suggest that PTOX controls the expression of responsive genes of the photosynthetic apparatus in a different way from the PQ/PQH 2 ratio. This article is part of the themed issue ‘Enhancing photosynthesis in crop plants: targets for improvement’.


2014 ◽  
Vol 122 (03) ◽  
Author(s):  
A Chatzigeorgiou ◽  
R Garcia-Martin ◽  
KJ Chung ◽  
I Alexaki ◽  
A Klotzsche-von Ameln ◽  
...  

2008 ◽  
Vol 3 (S 1) ◽  
Author(s):  
U Bernhardt ◽  
HG Joost ◽  
H Al-Hasani
Keyword(s):  

Author(s):  
Huihui Tang ◽  
Sungdae Park ◽  
Kam C. Yeung
Keyword(s):  

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