Institut de Biologie Physico-Chimique, Unité Mixte de Recherche 7141, Centre National de la Recherche Scientifique-Sorbonne Université, 75005 Paris, France.
Institut de Biologie Physico-Chimique, Unité Mixte de Recherche 7141, Centre National de la Recherche Scientifique-Sorbonne Université, 75005 Paris, France
Plant Physiol. 2019 Feb;179(2):630-639. doi: 10.1104/pp.18.01213. Epub 2018 Nov 29.
Whereas photosynthetic function under steady-state light conditions has been well characterized, little is known about its changes that occur in response to light fluctuations. Chlororespiration, a simplified respiratory chain, is widespread across all photosynthetic lineages, but its role remains elusive. Here, we show that chlororespiration plays a crucial role in intermittent-light conditions in the green alga Chlororespiration, which is localized in thylakoid membranes together with the photosynthetic electron transfer chain, involves plastoquinone reduction and plastoquinol oxidation by a Plastid Terminal Oxidase (PTOX). We show that PTOX activity is critical for growth under intermittent light, with severe growth defects being observed in a mutant lacking PTOX2, the major plastoquinol oxidase. We demonstrate that the hampered growth results from a major change in the kinetics of redox relaxation of the photosynthetic electron transfer chain during the dark periods. This change, in turn, has a dramatic effect on the physiology of photosynthesis during the light periods, notably stimulating cyclic electron flow at the expense of the linear electron flow.
虽然光合作用在稳态光条件下的功能已经得到了很好的描述，但对于其对光波动的响应所发生的变化却知之甚少。氯呼吸，一种简化的呼吸链，广泛存在于所有光合谱系中，但它的作用仍然难以捉摸。在这里，我们表明，氯呼吸在绿藻中的间歇性光照条件下起着至关重要的作用。氯呼吸与光合作用电子传递链一起定位于类囊体膜中，涉及质体醌还原和质体醇氧化由质体末端氧化酶（PTOX）。我们表明，PTOX 活性对于间歇性光照下的生长至关重要，在缺乏主要质体醇氧化酶 PTOX2 的突变体中观察到严重的生长缺陷。我们证明，生长受阻是由于在暗期期间光合作用电子传递链的氧化还原弛豫动力学发生了重大变化。这种变化反过来又对光期光合作用的生理学产生了巨大影响，特别是以牺牲线性电子流为代价刺激环式电子流。
