SGER: The Response of Marine Phytoplankton to Climate Change: Characterization of Rubisco Activase

无机碳在调节浮游植物群落的海洋生产力和物种组成方面起着至关重要的作用。因此，如果我们要了解浮游植物光合作用对全球气候变化的响应，并建立现实的海洋生物化学碳通量模型，了解不同浮游植物组合固定无机碳的机制是至关重要的。Rubisco是驱动Calvin循环功能的关键酶。然而，现在已经很好地证明了陆生植物Rubisco在没有Rubisco活化酶的协同作用的情况下是催化不起作用的。到目前为止，文献中还没有关于Rubisco激活酶对gLny色藻的作用的信息。事实上，除了赤潮异弯藻和两个圆柱藻以外，还没有关于在全球碳加工中如此关键的这一组合的任何其他代表的Rubisco催化功能的数据。本项目的目标是：a)使用Heterosigma作为模式色生藻种来分离和表征Rubisco激活酶；尤其是，b)扩展Rubisco激活酶的研究包括硅藻，因为它们是二氧化碳管理的主要贡献者。这项研究是可行的，因为：a)现在已经在大肠杆菌中过度表达了假定的Heterosigma激活酶基因；b)已经完成了对Heterosigma Rubisco的广泛分析；C)已经记录了对光信号响应的Rubisco mRNA的产生模式；d)异西格玛和硅藻Rubisco抗体已经被证明发生交叉反应；e)已经对抗体标记的Rubisco进行了流式细胞术测量。虽然在理解浮游植物中Rubisco激活酶对Rubisco的调节方面的努力可能是有风险的，但本研究将建立一个色藻的初级数据库，其中通过Rubisco/Rubisco激活酶的相互作用来解释无机碳加工的生物化学。从预测应对气候变化的光合作用表现来看，这项研究的长期益处是非常重要的。

Inorganic carbon plays a crucial role in regulating marine productivity and species composition in phytoplankton communities. Therefore understanding the mechanisms underlying inorganic carbon fixation by different phytoplankton assemblages is critical if we are to understand the response of phytoplankt on photosynthesis to global climate change, and to develop realistic models of biogeochernical carbon flux in the ocean.Rubisco is a keystone enzyme that drives Calvin cycle function. However, it is now well documented that terrestrial plant Rubisco is catalytically non?functional without the co?operative interplay of Rubisco activase. To date, no information exists in the literature concerning the function of Rubisco activase for gLny chromophytic alga. In fact, except for Heterosigma akashiwo and two Cylindrotheca species, no data exists on Rubisco catalytic function for any other representative of this assemblage that is so critical in global carbon processing.The Goals of this project are to: a) Isolate and characterize Rubisco activase using Heterosigma as model chromophytic algal species; and, in particular, to b) Extend Rubisco activase studies to include diatoms since they rank as primary contributors in C02 management.The study is feasible because: a) The cloned, putative Heterosigma activase gene has now been over?expressed in E. coli; b) Extensive analysis of Heterosigma Rubisco has been accomplished; c) Patterns of Rubisco mRNA production in response to light cues have been documented; d) Heterosigma and diatom Rubisco antibodies have been shown to cross react; e) Flow cytometric measurements of antibody?tagged Rubisco have been made.While the effort in understanding the regulation of Rubisco by Rubisco activase in phytoplankton may be risky, this study will establish a primary database for chromophytic algae wherein the biochemistry of inorganic carbon processing via Rubisco/Rubisco activase interaction is deciphered. The long?term benefit this study is highly significant when considered in terms of predicting photosynthetic performance in response to climate change.