Molecular cloning and targeting of a fibrillarin homolog from Arabidopsis
Molecular cloning and targeting of a fibrillarin homolog from Arabidopsis
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DOI：
10.1104/pp.123.1.51
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发表时间：
2000-05-01
期刊：
影响因子：
7.4
通讯作者：
Son, D
中科院分区：
文献类型：
--
作者：
Pih, KT;Yi, MJ;Son, D
纤维蛋白是一种核仁蛋白，参与核糖体RNA前体的加工。我们分离到了AtFbr1，这是一个编码拟南芥纤维蛋白同源物的基因。该基因全长1.2kb，编码310个氨基酸残基，分子质量为33kD。AtFbr1在花和根组织中高水平表达，在叶组织中略低水平表达，而在角果中几乎检测不到。将AtFbr1基因的表达与拟南芥基因组计划确定的FLP(纤维蛋白样蛋白)基因进行了比较。脱落酸处理导致幼苗中AtFbr1和FLP基因的表达下调，但FLP的抑制程度高于AtFbr1。此外，FLP的表达水平随着苗龄的增加而降低，而AtFbr1的表达水平没有表现出任何可检测到的变化。使用融合蛋白的体内靶向方法研究了AtFbr1的亚细胞定位，发现当以绿色荧光融合蛋白(GFP)的形式表达时，AtFbr1能够正确地靶向原生质体中的核仁。缺失实验表明，N末端的甘氨酸和精氨酸富集区是将AtFbr1靶向核仁的必要条件和充分条件。
Fibrillarin is a nucleolar protein known to be involved in the processing of ribosomal RNA precursors. We isolated AtFbr1, a cDNA encoding a homolog of fibrillarin in Arabidopsis. The cDNA is 1.2 kb in size and encodes a polypeptide of 310 amino acid residues with a molecular mass of 33 kD. AtFbr1 is expressed at high levels in the flower and root tissue and at a slightly lower level in leaf tissue, whereas it was nearly undetectable in siliques. Expression of AtFbr1 was compared with that of the FLP (fibrillarin-like protein) gene identified by the Arabidopsis genome project. Abscisic acid treatment resulted in the down-regulation of the expression of both AtFbr1 and FLP genes in seedlings, although the degree of suppression was higher for FLP than for AtFbr1. In addition, the expression level of FLP decreased with the age of the seedlings, whereas AtFbr1 did not exhibit any detectable change. The subcellular localization of AtFbr1 was studied with an in vivo targeting approach using a fusion protein, and was found to be correctly targeted to the nucleolus in protoplasts when expressed as a green fluorescent fusion protein (GFP). Deletion experiments showed that the N-terminal glycine- and arginine-rich region is necessary and sufficient to target AtFbr1 to the nucleolus.