Light History Influences the Response of the Marine Cyanobacterium Synechococcus sp WH7803 to Oxidative Stress
Light History Influences the Response of the Marine Cyanobacterium Synechococcus sp WH7803 to Oxidative Stress
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DOI：
10.1104/pp.111.174714
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发表时间：
2011-08-01
期刊：
影响因子：
7.4
通讯作者：
Garczarek, Laurence
中科院分区：
文献类型：
--
作者：
Blot, Nicolas;Mella-Flores, Daniella;Garczarek, Laurence
海洋聚球藻承受广泛的环境压力，特别是高且可变的辐照度，这可能通过产生活性氧（ROS）诱导氧化应激。虽然光和活性氧可以对光合作用损伤产生协同作用，诱导光损伤并抑制光系统 II 修复，但适应高辐照度也被认为可以赋予对其他应激源的抵抗力。为了确定光和ROS在光抑制过程中各自的作用并检测可能的光驱动的氧化应激耐受性，我们比较了聚球藻的光生理和转录组反应。 WH7803 适应低光 (LL) 或高光 (HL)，以应对由过氧化氢 (H2O2) 或甲基紫精诱导的氧化应激。虽然 HL 细胞的光合作用活性受到的影响比 LL 细胞大得多，但在添加 25 μM H2O2 后，只有 HL 细胞能够恢复生长和光合作用。根据光照条件和 H2O2 浓度，后一种氧化剂通过对反应中心的直接损害和其修复周期的抑制来诱导光系统 II 失活。尽管 LL 和 HL 细胞中的整体转录组反应看起来相似，但 HL 细胞中专门诱导了一些过程，这些过程似乎有助于它们抵御氧化应激，包括增强光保护和 ROS 解毒、修复 ROS 驱动的损伤以及调节氧化还原状态。检测假定的 LexA 结合位点可以鉴定假定的 LexA 调节子，与 LL 细胞相比，该调节子在 HL 细胞中下调，但在两种生长辐照下均因氧化应激而上调。
Marine Synechococcus undergo a wide range of environmental stressors, especially high and variable irradiance, which may induce oxidative stress through the generation of reactive oxygen species (ROS). While light and ROS could act synergistically on the impairment of photosynthesis, inducing photodamage and inhibiting photosystem II repair, acclimation to high irradiance is also thought to confer resistance to other stressors. To identify the respective roles of light and ROS in the photoinhibition process and detect a possible light-driven tolerance to oxidative stress, we compared the photophysiological and transcriptomic responses of Synechococcus sp. WH7803 acclimated to low light (LL) or high light (HL) to oxidative stress, induced by hydrogen peroxide (H2O2) or methylviologen. While photosynthetic activity was much more affected in HL than in LL cells, only HL cells were able to recover growth and photosynthesis after the addition of 25 mu M H2O2. Depending upon light conditions and H2O2 concentration, the latter oxidizing agent induced photosystem II inactivation through both direct damage to the reaction centers and inhibition of its repair cycle. Although the global transcriptome response appeared similar in LL and HL cells, some processes were specifically induced in HL cells that seemingly helped them withstand oxidative stress, including enhancement of photoprotection and ROS detoxification, repair of ROS-driven damage, and regulation of redox state. Detection of putative LexA binding sites allowed the identification of the putative LexA regulon, which was down-regulated in HL compared with LL cells but up-regulated by oxidative stress under both growth irradiances.