Ammonia Triggers Photodamage of Photosystem II in the Cyanobacterium Synechocystis sp. Strain PCC 6803

作者：Miriam Drath, Nicole Kloft, Alfred Batschauer, Kay Marin, Jens F. Novak, Karl Forchhammer · 发表于：PLANT PHYSIOLOGY · 年份：2008 · DOI：10.1104/pp.108.117218 · 被引用次数：181 · 研究领域：Photosynthetic Processes and Mechanisms、Algal biology and biofuel production、Marine and coastal ecosystems

Ammonia has long been known to be toxic for many photosynthetic organisms; however, the target for its toxicity remains elusive. Here, we show that in the cyanobacterium Synechocystis sp. strain PCC 6803, ammonia triggers a rapid photodamage of photosystem II (PSII). Whereas wild-type cells can cope with this damage by turning on the FtsH2-dependent PSII repair cycle, the FtsH2-deficient mutant is highly sensitive and loses PSII activity at millimolar concentration of ammonia. Ammonia-triggered PSII destruction is light dependent and occurs already at low photon fluence rates. Experiments with monochromatic light showed that ammonia-promoted PSII photoinhibition is executed by wavebands known to directly destroy the manganese cluster in the PSII oxygen-evolving complex, suggesting that the oxygen-evolving complex may be a direct target for ammonia toxicity.