Ccm1, a regulatory gene controlling the induction of a carbon-concentrating mechanism in Chlamydomonas reinhardtii by sensing CO2 availability
Ccm1, a regulatory gene controlling the induction of a carbon-concentrating mechanism in Chlamydomonas reinhardtii by sensing CO2 availability
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DOI：
10.1073/pnas.081593498
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发表时间：
2001-04-24
影响因子：
11.1
通讯作者：
Ohyama, K
中科院分区：
文献类型：
--
作者：
Fukuzawa, H;Miura, K;Ohyama, K
水生光合生物，包括绿藻莱茵衣藻，诱导一组碳浓缩机制（CCM）基因以适应二氧化碳限制条件。这种适应是通过细胞中的一些机制来调节的，以感知二氧化碳的可用性。此前，通过基因标记从莱因哈特衣藻中分离出了 CCM 诱导缺陷的高 CO2 需求突变体 C16。通过使用这种多效性突变体，我们分离出一个核调节基因 Ccm1，它编码一个 699 个氨基酸的亲水蛋白，在其 N 端区域具有推定的锌指基序和转录激活子的 Gin 重复特征。将 Ccm1 引入该突变体恢复了通过 CCM 的活性碳运输，在叶绿体中形成了蛋白核结构。以及一组 CCM 相关基因的诱导。在高 CO2 和低 CO2 条件下均检测到 5,128 个碱基的 Ccm1 转录物以及 76 kDa 的翻译产物，这表明 CCM1 可能会在翻译后发生修饰。这些数据表明，Ccm1 对于通过感知衣藻细胞中 CO2 的可用性来控制 CCM 的诱导至关重要。此外，互补分析和对另一种多效突变体 cia5 突变位点的鉴定表明，CCM1 假定的锌指基序内的 His-54 对于其调节功能至关重要。
Aquatic photosynthetic organisms, including the green alga Chlamydomonas reinhardtii, induce a set of genes for a carbon-concentrating mechanism (CCM) to acclimate to CO2-limiting conditions. This acclimation is modulated by some mechanisms in the cell to sense CO2 availability. Previously, a high-CO2-requiring mutant C16 defective in an induction of the CCM was isolated from C,reinhardtii by gene tagging. By using this pleiotropic mutant, we isolated a nuclear regulatory gene, Ccm1, encoding a 699-aa hydrophilic protein with a putative zinc-finger motif in its N-terminal region and a Gin repeat characteristic of transcriptional activators, Introduction of Ccm1 into this mutant restored an active carbon transport through the CCM, development of a pyrenoid structure in the chloroplast. and induction of a set of CCM-related genes. That a 5,128-base Ccm1 transcript and also the translation product of 76 kDa were detected in both high- and low-CO2 conditions suggests that CCM1 might be modified posttranslationally. These data indicate that Ccm1 is essential to control the induction of CCM by sensing CO2 availability in Chlamydomonas cells. In addition, complementation assay and identification of the mutation site of another pleiotropic mutant, cia5, revealed that His-54 within the putative zinc-finger motif of the CCM1 is crucial to its regulatory function.