Fukayama H, Tsuchida H, Agarie S, Nomura M, Onodera H, Ono K, Lee B H, Hirose S, Toki S, Ku M S, Makino A, Matsuoka M, Miyao M
National Institute of Agrobiological Sciences, Tsukuba 305-8602, Japan.
Plant Physiol. 2001 Nov;127(3):1136-46.
The C(4)-Pdk gene encoding the C(4) enzyme pyruvate, orthophosphate dikinase (PPDK) of maize (Zea mays cv Golden Cross Bantam) was introduced into the C(3) plant, rice (Oryza sativa cv Kitaake). When the intact maize C(4)-Pdk gene, containing its own promoter and terminator sequences and exon/intron structure, was introduced, the PPDK activity in the leaves of some transgenic lines was greatly increased, in one line reaching 40-fold over that of wild-type plants. In a homozygous line, the PPDK protein accounted for 35% of total leaf-soluble protein or 16% of total leaf nitrogen. In contrast, introduction of a chimeric gene containing the full-length cDNA of the maize PPDK fused to the maize C(4)-Pdk promoter or the rice Cab promoter only increased PPDK activity and protein level slightly. These observations suggest that the intron(s) or the terminator sequence of the maize gene, or a combination of both, is necessary for high-level expression. In maize and transgenic rice plants carrying the intact maize gene, the level of transcript in the leaves per copy of the maize C(4)-Pdk gene was comparable, and the maize gene was expressed in a similar organ-specific manner. These results suggest that the maize C(4)-Pdk gene behaves in a quantitatively and qualitatively similar way in maize and transgenic rice plants. The activity of the maize PPDK protein expressed in rice leaves was light/dark regulated as it is in maize. This is the first reported evidence for the presence of an endogenous PPDK regulatory protein in a C(3) plant.
将编码玉米（Zea mays cv Golden Cross Bantam）C4酶丙酮酸磷酸双激酶（PPDK）的C(4)-Pdk基因导入C3植物水稻（Oryza sativa cv Kitaake）。当导入包含自身启动子、终止子序列以及外显子/内含子结构的完整玉米C(4)-Pdk基因时，部分转基因系叶片中的PPDK活性大幅增加，其中一个系的活性比野生型植株高出40倍。在一个纯合系中，PPDK蛋白占叶片可溶性蛋白总量的35%或叶片总氮量的16%。相比之下，导入一个嵌合基因，该基因包含与玉米C(4)-Pdk启动子或水稻Cab启动子融合的玉米PPDK全长cDNA，仅使PPDK活性和蛋白水平略有增加。这些观察结果表明，玉米基因的内含子或终止子序列，或两者的组合，对于高水平表达是必需的。在携带完整玉米基因的玉米和转基因水稻植株中，每拷贝玉米C(4)-Pdk基因在叶片中的转录水平相当，并且玉米基因以类似的器官特异性方式表达。这些结果表明，玉米C(4)-Pdk基因在玉米和转基因水稻植株中的行为在数量和质量上相似。水稻叶片中表达的玉米PPDK蛋白的活性如同在玉米中一样受光/暗调节。这是首次报道在C3植物中存在内源性PPDK调节蛋白的证据。
