Galzerano Denise, Feilke Kathleen, Schaub Patrick, Beyer Peter, Krieger-Liszkay Anja
Commissariat à l'Energie Atomique (CEA) Saclay, iBiTec-S, CNRS UMR 8221, Service de Bioénergétique, Biologie Structurale et Mécanisme, 91191 Gif-sur-Yvette Cedex, France.
Faculty of Biology, University of Freiburg, 79104 Freiburg, Germany.
Biochim Biophys Acta. 2014 Mar;1837(3):345-53. doi: 10.1016/j.bbabio.2013.12.010. Epub 2013 Dec 27.
The constitutive expression of the bacterial carotene desaturase (CRTI) in Arabidopsis thaliana leads to increased susceptibility of leaves to light-induced damage. Changes in the photosynthetic electron transport chain rather than alterations of the carotenoid composition in the antenna were responsible for the increased photoinhibition. A much higher level of superoxide/hydrogen peroxide was generated in the light in thylakoid membranes from the CRTI expressing lines than in wild-type while the level of singlet oxygen generation remained unchanged. The increase in reactive oxygen species was related to the activity of plastid terminal oxidase (PTOX) since their generation was inhibited by the PTOX-inhibitor octyl gallate, and since the protein level of PTOX was increased in the CRTI-expressing lines. Furthermore, cyclic electron flow was suppressed in these lines. We propose that PTOX competes efficiently with cyclic electron flow for plastoquinol in the CRTI-expressing lines and that it plays a crucial role in the control of the reduction state of the plastoquinone pool.
细菌类胡萝卜素去饱和酶（CRTI）在拟南芥中的组成型表达导致叶片对光诱导损伤的敏感性增加。光合电子传递链的变化而非天线中类胡萝卜素组成的改变是光抑制增加的原因。与野生型相比，来自CRTI表达系的类囊体膜在光照下产生的超氧化物/过氧化氢水平要高得多，而单线态氧的产生水平保持不变。活性氧的增加与质体末端氧化酶（PTOX）的活性有关，因为其产生受到PTOX抑制剂没食子酸辛酯的抑制，并且因为CRTI表达系中PTOX的蛋白质水平增加。此外，这些品系中的循环电子流受到抑制。我们提出，在CRTI表达系中，PTOX与循环电子流有效竞争质体醌，并且它在控制质体醌库的还原状态中起关键作用。
