Rehman Ateeq Ur, Kodru Sandeesha, Vass Imre
Institute of Plant Biology, Biological Research Centre of the Hungarian Academy of Sciences Szeged, Hungary.
Front Plant Sci. 2016 Apr 8;7:479. doi: 10.3389/fpls.2016.00479. eCollection 2016.
Chloramphenicol (CAP) is an inhibitor of protein synthesis, which is frequently used to decouple photodamage and protein synthesis dependent repair of Photosystem II during the process of photoinhibition. It has been reported earlier that CAP is able to mediate superoxide production by transferring electrons from the acceptor side of Photosystem I to oxygen. Here we investigated the interaction of CAP with Photosystem II electron transport processes by oxygen uptake and variable chlorophyll fluorescence measurements. Our data show that CAP can accept electrons at the acceptor side of Photosystem II, most likely from Pheophytin, and deliver them to molecular oxygen leading to superoxide production. In addition, the presence of CAP enhances photodamage of Photosystem II electron transport in isolated membrane particles, which effect is reversible by superoxide dismutase. It is concluded that CAP acts as electron acceptor in Photosystem II and mediates its superoxide dependent photodamage. This effect has potential implications for the application of CAP in photoinhibitory studies in intact systems.
氯霉素（CAP）是一种蛋白质合成抑制剂，在光抑制过程中常用于解耦光损伤和依赖蛋白质合成的光系统II修复。此前有报道称，CAP能够通过将电子从光系统I的受体侧转移到氧来介导超氧阴离子的产生。在这里，我们通过氧摄取和可变叶绿素荧光测量研究了CAP与光系统II电子传输过程的相互作用。我们的数据表明，CAP可以在光系统II的受体侧接受电子，最有可能来自脱镁叶绿素，并将它们传递给分子氧，导致超氧阴离子的产生。此外，CAP的存在会增强分离膜颗粒中光系统II电子传输的光损伤，超氧化物歧化酶可使这种效应逆转。结论是，CAP在光系统II中充当电子受体，并介导其依赖超氧阴离子的光损伤。这种效应对于CAP在完整系统的光抑制研究中的应用具有潜在意义。
