Recent progresses on the genetic basis of the regulation of CO2 acquisition systems in response to CO2 concentration
Recent progresses on the genetic basis of the regulation of CO2 acquisition systems in response to CO2 concentration
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DOI：
10.1007/s11120-011-9623-7
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发表时间：
2011-02
影响因子：
3.7
通讯作者：
Y. Matsuda;Kensuke Nakajima;M. Tachibana
中科院分区：
文献类型：
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作者：
Y. Matsuda;Kensuke Nakajima;M. Tachibana
海洋硅藻是海洋环境中主要的初级生产者，已知它们可以吸收海水中的CO2和HCO 3 −，并将其有效地集中在细胞内，这使得硅藻细胞能够在有限的CO2下进行高亲和力的光合作用。然而，机制迄今提出的无机碳收购海洋硅藻显着不同，尽管在这方面的生理研究已经完成了只有有限的物种数量。关于这一点有两个主要的假设：一是它们吸收并浓缩无机形式的CO2和HCO 3 −，并通过碳酸酐酶的帮助有效地向Rubisco提供CO2（生物物理CO2浓缩机制：CCM）;另一个假设是HCO 3 −向C4化合物的生化转化可能在向Rubisco提供浓缩的CO2方面发挥重要作用。然而，目前，这些假说的生理学证据与分子水平的证据没有很好的联系。本文综述了近年来植物碳代谢相关基因的分子研究进展，主要涉及植物碳获取的生理方面。此外，我们还讨论了调节CO2捕获系统的机制，以响应pCO 2的变化。cAMP参与CO2浓度信号通路的最新研究结果有力地表明硅藻中存在着对pCO 2变化作出反应的类囊藻型信号通路。事实上，有相当数量的推定腺苷酸环化酶，这可能是参与过程中的CO2信号捕获。
Marine diatoms, the major primary producer in ocean environment, are known to take up both CO2and HCO3−in seawater and efficiently concentrate them intracellularly, which enable diatom cells to perform high-affinity photosynthesis under limiting CO2. However, mechanisms so far proposed for the inorganic carbon acquisition in marine diatoms are significantly diverse despite that physiological studies on this aspect have been done with only limited number of species. There are two major hypotheses about this; that is, they take up and concentrate both CO2and HCO3−as inorganic forms, and efficiently supply CO2to Rubisco by an aid of carbonic anhydrases (biophysical CO2-concentrating mechanism: CCM); and as the other hypothesis, biochemical conversion of HCO3−into C4compounds may play a major role to supply concentrated CO2to Rubisco. At moment however, physiological evidence for these hypotheses were not related well to molecular level evidence. In this study, recent progresses in molecular studies on diatom-carbon-metabolism genes were related to the physiological aspects of carbon acquisition. Furthermore, we discussed the mechanisms regulating CO2acquisition systems in response to changes inpCO2. Recent findings about the participation of cAMP in the signaling pathway of CO2concentration strongly suggested the occurrences of mammalian-type-signaling pathways in diatoms to respond to changes inpCO2. In fact, there were considerable numbers of putative adenylyl cyclases, which may take part in the processes of CO2signal capturing.