Okanami M, Meshi T, Iwabuchi M
Department of Botany, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan.
Nucleic Acids Res. 1998 Jun 1;26(11):2638-43. doi: 10.1093/nar/26.11.2638.
We have isolated cDNAs encoding a novel member of the DEAD box RNA helicase family from Arabidopsis. The protein, named AtDRH1, is composed of 619 amino acids and the central portion has high similarity with the helicase core region of a prototypic RNA helicase, the human nuclear protein p68. The N- and C-terminal regions are considerably diverged from the animal and yeast p68 homologs at the amino acid sequence level, but like the p68 subfamily members, an RGG box-like domain is present near the C-terminus. RNA blot analysis showed that the AtDRH1 transcript accumulates at a high level and almost equally in every part of the Arabidopsis plant. The purified, recombinant AtDRH1 was capable of unwinding double-stranded RNA in the presence of ATP or dATP and of hydrolyzing ATP. The ATPase activity was stimulated by some single-stranded RNAs and DNAs, including poly(A) and poly(dT), but not by poly(dA). The ability of the polynucleotides to stimulate the ATPase activity was largely consistent with their affinity for AtDRH1. These results show that AtDRH1 is a novel type of ATP/dATP-dependent RNA helicase and polynucleotide-dependent ATPase.
我们从拟南芥中分离出了编码DEAD盒RNA解旋酶家族一个新成员的cDNA。该蛋白名为AtDRH1，由619个氨基酸组成，其中心部分与原型RNA解旋酶（人核蛋白p68）的解旋酶核心区域具有高度相似性。在氨基酸序列水平上，其N端和C端区域与动物和酵母的p68同源物有很大差异，但与p68亚家族成员一样，在C端附近存在一个类似RGG盒的结构域。RNA印迹分析表明，AtDRH1转录本在拟南芥植株的各个部位均高水平积累且几乎相等。纯化的重组AtDRH1在ATP或dATP存在的情况下能够解开双链RNA，并能水解ATP。一些单链RNA和DNA，包括聚腺苷酸（poly(A)）和聚胸腺嘧啶脱氧核苷酸（poly(dT)）能刺激ATP酶活性，但聚脱氧腺苷酸（poly(dA)）不能。多核苷酸刺激ATP酶活性的能力与其对AtDRH1的亲和力基本一致。这些结果表明，AtDRH1是一种新型的ATP/dATP依赖性RNA解旋酶和多核苷酸依赖性ATP酶。
