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

无机碳在调节海洋生产力和浮游植物群落的物种组成中起着至关重要的作用。因此，了解不同浮游植物组合的无机固碳机制对于了解植物光合作用对全球气候变化的响应以及建立海洋生物地球化学碳通量的现实模型至关重要。Rubisco是驱动卡尔文循环功能的关键酶。然而，现在有充分的证据表明，陆生植物Rubisco具有催化非？没有co的功能？Rubisco活化酶的作用相互作用。迄今为止，尚无文献报道Rubisco激活酶对gLny色藻的作用。事实上，除了Heterosigma akashiwo和两个柱石菌外，没有关于Rubisco催化功能的数据存在于该组合的任何其他代表中，这在全球碳加工中是如此重要。本项目的目标是：a)利用异辛格玛作为模型色藻分离和表征Rubisco激活酶；特别是，b)将Rubisco激活酶的研究扩展到硅藻，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)克隆的，假定的异sigma激活酶基因现在已经结束了？在大肠杆菌中表达；b)完成了对Rubisco的广泛分析；c) Rubisco mRNA对光信号的响应模式已被记录；d)异sigma和硅藻Rubisco抗体已被证明交叉反应；e)抗体的流式细胞术测定？标记Rubisco已被制成。虽然了解浮游植物中Rubisco活化酶对Rubisco的调控可能存在风险，但本研究将建立一个主要的色藻数据库，其中通过Rubisco/Rubisco活化酶相互作用来破译无机碳加工的生物化学过程。长吗?当考虑到预测光合作用性能对气候变化的响应时，这项研究的长期效益是非常显著的。

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.