Fabre Nicolas, Reiter Ilja M, Becuwe-Linka Noelle, Genty Bernard, Rumeau Dominique
CEA/Cadarache, DSV, DEVM, Laboratoire d'Ecophysiologie Moléculaire des Plantes, UMR 6191 CNRS-CEA-Université de la Méditerranée, 13108 Saint-Paul-lez-Durance, Cedex, France.
Plant Cell Environ. 2007 May;30(5):617-29. doi: 10.1111/j.1365-3040.2007.01651.x.
Carbonic anhydrases (CAs) are Zn-containing metalloenzymes that catalyse the reversible hydration of CO(2). We investigated the alphaCA and betaCA families in Arabidopsis, which contain eight alphaCA (At alphaCA1-8) and six betaCA genes (At betaCA1-6). Analyses of expressed sequence tags (ESTs) from The Arabidopsis Information Resource (TAIR) database indicate that all the betaCA encoding sequences, but only three of the At alphaCA, are expressed. Using semi-quantitative PCR experiments, functional CA genes were more strongly expressed in green tissue, but strong expression was also found in roots for betaCA3, betaCA6 and alphaCA2. Two alphaCA genes were shown to respond to the CO(2) environment, while the others were unresponsive. Using the green fluorescent reporter protein gene fused with cDNA sequences coding for betaCAs, we provided evidence that betaCAs were targeted to specific subcellular compartments: betaCA1 and betaCA5 were targeted to the chloroplast, betaCA2 and betaCA3 to the cytosol, betaCA4 to the plasma membrane and betaCA6 to the mitochondria. The targeting and the pattern of gene expression suggest that CA isoforms play specific roles in subcellular compartments, tissues and organs. The data indicate that other CA isoforms than the well-characterized betaCA1 may contribute to the CO(2) transfer in the cell to the catalytic site of ribulose 1.5-bisphosphate carboxylase/oxygenase (Rubisco).
碳酸酐酶（CAs）是含锌金属酶，可催化二氧化碳的可逆水合作用。我们研究了拟南芥中的αCA和βCA家族，其中包含8个αCA基因（AtαCA1 - 8）和6个βCA基因（AtβCA1 - 6）。对拟南芥信息资源（TAIR）数据库中的表达序列标签（EST）分析表明，所有βCA编码序列均有表达，但AtαCA中只有3个有表达。通过半定量PCR实验发现，功能性CA基因在绿色组织中表达更强，但βCA3、βCA6和αCA2在根中也有强表达。有两个αCA基因显示对二氧化碳环境有响应，而其他基因无响应。利用与βCAs编码cDNA序列融合的绿色荧光报告蛋白基因，我们证明βCAs定位于特定的亚细胞区室：βCA1和βCA5定位于叶绿体，βCA2和βCA3定位于细胞质，βCA4定位于质膜，βCA6定位于线粒体。这种定位和基因表达模式表明CA同工型在亚细胞区室、组织和器官中发挥特定作用。数据表明，除了已充分研究的βCA1外，其他CA同工型可能也有助于细胞中二氧化碳向1,5 - 二磷酸核酮糖羧化酶/加氧酶（Rubisco）催化位点的转移。
