Cellular distribution of ACT domain repeat protein 9, a nuclear localizing protein, in rice (Oryza sativa)
Cellular distribution of ACT domain repeat protein 9, a nuclear localizing protein, in rice (Oryza sativa)
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DOI：
10.1111/j.1399-3054.2008.01051.x
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发表时间：
2008-06-01
影响因子：
6.4
通讯作者：
Hayakawa, Toshihiko
中科院分区：
文献类型：
--
作者：
Kudo, Toru;Kawai, Akiko;Hayakawa, Toshihiko
调节ACT结构域是细菌中某些氨基酸代谢酶和转录调节因子中的氨基酸结合部位。植物中的ACT结构域重复蛋白(ACR)家族主要由4个与细菌GLN传感器GLND同源的结构域组成。为了探讨OsACR9蛋白在水稻氮素代谢相关的谷氨酰胺敏感系统中的作用，本研究分别采用瞬时表达分析和免疫学方法检测了OsACR9的亚细胞定位及其在水稻各器官中的积累和细胞分布。在培养的水稻细胞中，OsACR9与合成的绿色荧光蛋白融合的瞬时表达分析表明OsACR9的核定位。在水稻根中，OsACR9蛋白主要分布在表皮、外胚层、厚壁组织和维管薄壁细胞中，在NH4+胁迫下，水稻根中OsACR9蛋白的积累显著增加。在水稻叶片样品中，OsACR9蛋白在幼叶发育早期的维管组织和中鞘细胞以及成熟叶鞘的维管组织和韧皮部伴生细胞中含量丰富。在早熟阶段，OsACR9蛋白在幼粒背部维管束的维管组织细胞和糊粉细胞中也有较高水平的积累。随后，通过比较水稻核蛋白OsACR9与谷氨酰胺反应N同化基因的时空表达，探讨了它作为谷氨酰胺感受器的可能性。
Regulatory ACT domains serve as amino acid-binding sites in certain amino acid metabolic enzymes and transcriptional regulators in bacteria. The ACT domain repeat protein (ACR) family in plants is primarily composed of four copies of the domain homologous to those of the bacteria Gln sensor GLND. In the current study, to evaluate the possible involvement of the protein OsACR9 in the Gln-sensing system related to nitrogen (N) metabolism in rice (Oryza sativa L.), subcellular localization of OsACR9 and its accumulation and cellular distribution in various rice organs were examined by transient expression analysis and immunological methods using a monospecific antibody, respectively. Transient expression analysis of OsACR9 fused with a synthetic green fluorescent protein in cultured rice cells suggested nuclear localization of OsACR9. In rice roots, OsACR9 protein was distributed in epidermis, exodermis, sclerenchyma and vascular parenchyma cells, and its accumulation markedly increased after supply of NH4+. In rice leaf samples, OsACR9 protein was abundant in the vascular parenchyma and mestome-sheath cells of young leaf blades at the early stage of development and in the vascular parenchyma and phloem-companion cells of mature leaf sheaths. OsACR9 protein also showed a high level of accumulation in vascular parenchyma cells of dorsal vascular bundles and aleurone cells in young rice grains at the early stage of ripening. The possibility of the nuclear protein OsACR9 acting as a Gln sensor in rice is subsequently discussed through comparison of its spatiotemporal expression with that of Gln-responsive N-assimilatory genes.