Molecular cloning, gene expression and functional expression of a phosphoenolpyruvate carboxylase Osppc1 in developing rice seeds: implication of involvement in nitrogen accumulation.
Molecular cloning, gene expression and functional expression of a phosphoenolpyruvate carboxylase Osppc1 in developing rice seeds: implication of involvement in nitrogen accumulation.
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水稻种子发育过程中磷酸烯醇丙酮酸羧化酶 Osppc1 的分子克隆、基因表达和功能表达：参与氮积累的意义。
DOI：
10.1017/s0960258513000354
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发表时间：
2014
影响因子：
2.1
通讯作者：
Yoshikiyo Oji
中科院分区：
文献类型：
--
作者：
Naoki Yamamoto;Tatsuya Kubota;Takehiro Masumura;Naomasa Shiraishi;Kunisuke Tanaka;Toshio Sugimoto;Yoshikiyo Oji
我们从发育中的水稻种子中分离了两个磷酸烯醇式丙酮酸羧化酶（PEPC）的cDNA，Osppc 1和Osppc 3。这两个cDNA的推导的氨基酸序列与其他非光合PEPCases共享几个保守的基序，这些共同的基序是已知的是功能上重要的调节特性。在植物PEPCases系统进化树中，Osppc 1和Osppc 3分别被聚为单子叶植物和禾本科植物的一个分支。Osppc 1和Osppc 3的mRNA在水稻籽粒发育过程中积累，但其表达模式不同：Osppc 1在开花后7 d强表达，Osppc 3在开花后4 d强表达。Osppc 1重组蛋白的动力学性质与玉米根型PEPCase的动力学性质非常相似，除了在pH 7.3下对苹果酸的敏感性较弱。挖掘水稻基因芯片数据，我们发现Osppc 1与种子氮代谢相关的天冬氨酸转氨酶和丙氨酸转氨酶共表达。此外，重新注释的共表达基因显示，Osppc 1，两个氨基转移酶和烯醇化酶被映射到连续的反应，从2-磷酸甘油酸谷氨酸和丙酮酸在胞质溶胶中。这些结果表明，Osppc 1功能合作的两个氨基转移酶的氨基酸合成，用于存储蛋白质的合成在发展中的水稻种子。
We isolated two cDNAs of phosphoenolpyruvate carboxylase (PEPC) from developing rice seeds, Osppc1 and Osppc3. The deduced amino acid sequences of both cDNAs share several conserved motifs with other non-photosynthetic PEPCases, and these common motifs are known to be functionally important to their regulatory properties. The deduced protein sequence of Osppc1 was clustered into a monocotyledonous plant-specific clade, and Osppc3 was clustered into a gramineous plant-specific clade in the phylogenetic tree of plant PEPCases. The mRNA accumulations of Osppc1 and Osppc3 were found in developing rice seeds throughout the grain-filling stages, although their expression patterns differed: Osppc1 was strongly expressed at 7 d after flowering, and Osppc3 was strongly expressed at 4 d after flowering. The kinetic properties of the Osppc1 recombinant protein were quite similar to those of maize root-type PEPCase, except that the sensitivity for malate at pH 7.3 was weaker. Mining rice microarray data, we observed that Osppc1 was co-expressed with aspartate aminotransferase and alanine aminotransferase, which are involved in seed nitrogen metabolism. Moreover, reannotation of the co-expressed genes revealed that Osppc1, the two aminotransferases and the enolase were mapped on to the consecutive reaction from 2-phosphoglycerate to glutamate and pyruvate in the cytosol. These results imply that Osppc1 functions cooperatively with the two aminotransferases in the synthesis of amino acids that are used for storage protein synthesis in developing rice seeds.