Gu Lili, Jung Hyun Ju, Kim Bo Mi, Xu Tao, Lee Kwanuk, Kim Yeon-Ok, Kang Hunseung
Department of Plant Biotechnology, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 500-757, Republic of Korea.
Department of Plant Biotechnology, College of Agriculture and Life Sciences, Chonnam National University, Gwangju 500-757, Republic of Korea; College of Life Science, Jiangsu Normal University, Xuzhou 221116, Jiangsu Province, PR China.
J Plant Physiol. 2015 Sep 15;189:34-41. doi: 10.1016/j.jplph.2015.10.003. Epub 2015 Oct 22.
Although the roles of S1 domain-containing proteins have been characterized in diverse cellular processes in the cytoplasm, the functional roles of a majority of S1 domain-containing proteins targeted to the chloroplast are largely unknown. Here, we characterized the function of a nuclear-encoded chloroplast-targeted protein harboring two S1 domains, designated SRRP1 (for S1 RNA-binding ribosomal protein 1), in Arabidopsis thaliana. Subcellular localization analysis of SRRP1-GFP fusion proteins revealed that SRRP1 is localized to the chloroplast. The T-DNA tagged loss-of-function srrp1 mutants displayed poorer seedling growth and less cotyledon greening than the wild-type plants on MS medium supplemented with abscisic acid (ABA), suggesting that SRRP1 plays a role in seedling growth in the presence of ABA. Splicing of the trnL intron and processing of 5S rRNA in chloroplasts were altered in the mutant plants. Importantly, SRRP1 complemented the growth-defective phenotypes of an RNA chaperone-deficient Escherichia coli mutant at low temperatures and had nucleic acid-melting ability, indicating that SRRP1 possesses RNA chaperone activity. Taken together, these results suggest that SRRP1, the chloroplast-localized S1 domain-containing protein, harboring RNA chaperone activity affects the splicing and processing of chloroplast transcripts and plays a role in Arabidopsis seedling growth in the presence of ABA.
尽管含S1结构域的蛋白质在细胞质中的多种细胞过程中的作用已得到表征，但大多数靶向叶绿体的含S1结构域的蛋白质的功能作用仍 largely未知。在这里，我们表征了拟南芥中一种具有两个S1结构域的核编码叶绿体靶向蛋白的功能，该蛋白命名为SRRP1（S1 RNA结合核糖体蛋白1）。SRRP1-GFP融合蛋白的亚细胞定位分析表明SRRP1定位于叶绿体。T-DNA标签的功能缺失型srrp1突变体在添加脱落酸（ABA）的MS培养基上比野生型植物表现出更差的幼苗生长和更少的子叶绿化，这表明SRRP1在ABA存在下的幼苗生长中起作用。突变植物中叶绿体中trnL内含子的剪接和5S rRNA的加工发生了改变。重要的是，SRRP1在低温下补充了RNA伴侣缺陷型大肠杆菌突变体的生长缺陷表型并具有核酸解链能力，表明SRRP1具有RNA伴侣活性。综上所述，这些结果表明，叶绿体定位的含S1结构域的蛋白质SRRP1具有RNA伴侣活性，影响叶绿体转录本的剪接和加工，并在ABA存在下的拟南芥幼苗生长中起作用。
