Xu Jie, Liu Chaolei, Li Meiru, Hu Jiang, Zhu Li, Zeng Dali, Yang Yaolong, Peng Youlin, Ruan Banpu, Guo Longbiao, Li Hongqing
State Key Laboratory of Rice Biology, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310006, China; Key Laboratory of Crop Physiology, Ecology and Genetic Breeding, Ministry of Education, Jiangxi Agricultural University, Nanchang 330045, China.
State Key Laboratory of Rice Biology, China National Rice Research Institute, Chinese Academy of Agricultural Sciences, Hangzhou 310006, China.
Gene. 2015 Jan 25;555(2):318-28. doi: 10.1016/j.gene.2014.11.025. Epub 2014 Nov 14.
DEAD-box proteins comprise a large protein family. These proteins function in all types of processes in RNA metabolism and are highly conserved among eukaryotes. However, the precise functions of DEAD-box proteins in rice physiology and development remain unclear. In this study, we identified a rice DEAD-box protein, OsRH17, that contains a DEAD domain and all of the common conserved motifs of DEAD-box RNA helicases. OsRH17 was specifically expressed in pollen and differentiated callus and upregulated by application of the plant hormones naphthyl acetic acid (NAA) and abscisic acid (ABA). The OsRH17:GFP fusion protein was localized to the nucleus. Tiny amounts of OsRH17 and partial fragments (N-427 and C-167) were detected when they were expressed in Escherichia coli, a prokaryote. Growth of the host cells was suppressed in E. coli by OsRH17, N-427 or C-167, and this suppression was independent of the concentration of the NaCl in the medium. Expression analysis of rRNAs in E. coli revealed that the 16S rRNA precursor accumulated in transgenic E. coli cells, and the relative growth rate was inversely proportional to the levels of pre-16S rRNA accumulation. Results suggested that OsRH17 may play a role in ribosomal biogenesis and suppress 16S rRNA maturation in E. coli. No visible phenotype was observed in transgenic yeast and rice (overexpressing OsRH17, N-427, and C-167, as well as OsRH17 knockdown), and even in some abiotic and biotic stresses, which could be due to the redundancy in rice under normal conditions.
DEAD-box蛋白构成了一个庞大的蛋白质家族。这些蛋白质在RNA代谢的所有类型过程中发挥作用，并且在真核生物中高度保守。然而，DEAD-box蛋白在水稻生理和发育中的精确功能仍不清楚。在本研究中，我们鉴定了一种水稻DEAD-box蛋白OsRH17，它含有一个DEAD结构域以及DEAD-box RNA解旋酶的所有常见保守基序。OsRH17在花粉和分化的愈伤组织中特异性表达，并通过施加植物激素萘乙酸（NAA）和脱落酸（ABA）而上调。OsRH17:GFP融合蛋白定位于细胞核。当在原核生物大肠杆菌中表达时，检测到少量的OsRH17及其部分片段（N-427和C-167）。在大肠杆菌中，OsRH17、N-427或C-167抑制宿主细胞的生长，并且这种抑制与培养基中NaCl的浓度无关。对大肠杆菌中rRNA的表达分析表明，16S rRNA前体在转基因大肠杆菌细胞中积累，相对生长速率与前体16S rRNA的积累水平成反比。结果表明，OsRH17可能在核糖体生物合成中发挥作用，并抑制大肠杆菌中16S rRNA的成熟。在转基因酵母和水稻（过表达OsRH17、N-427和C-167以及敲低OsRH17）中未观察到明显的表型，甚至在一些非生物和生物胁迫下也未观察到，这可能是由于水稻在正常条件下存在冗余性。
