Kharrat A, Macias M J, Gibson T J, Nilges M, Pastore A
European Molecular Biology Laboratory, Heidelberg, Germany.
EMBO J. 1995 Jul 17;14(14):3572-84. doi: 10.1002/j.1460-2075.1995.tb07363.x.
The double-stranded RNA binding domain (dsRBD) is a approximately 70 residue motif found in a variety of modular proteins exhibiting diverse functions, yet always in association with dsRNA. We report here the structure of the dsRBD from RNase III, an enzyme present in most, perhaps all, living cells. It is involved in processing transcripts, such as rRNA precursors, by cleavage at short hairpin sequences. The RNase III protein consists of two modules, a approximately 150 residue N-terminal catalytic domain and a approximately 70 residue C-terminal recognition module, homologous with other dsRBDs. The structure of the dsRBD expressed in Escherichia coli has been investigated by homonuclear NMR techniques and solved with the aid of a novel calculation strategy. It was found to have an alpha-beta-beta-beta-alpha topology in which a three-stranded anti-parallel beta-sheet packs on one side against the two helices. Examination of 44 aligned dsRBD sequences reveals several conserved, positively charged residues. These residues map to the N-terminus of the second helix and a nearby loop, leading to a model for the possible contacts between the domain and dsRNA.
双链RNA结合结构域（dsRBD）是一种约70个残基的基序，存在于多种具有不同功能的模块化蛋白质中，但总是与双链RNA相关联。我们在此报告来自核糖核酸酶III的dsRBD的结构，核糖核酸酶III是一种存在于大多数（可能是所有）活细胞中的酶。它通过在短发夹序列处切割来参与转录本的加工，如rRNA前体。核糖核酸酶III蛋白由两个模块组成，一个约150个残基的N端催化结构域和一个约70个残基的C端识别模块，与其他dsRBD同源。通过同核核磁共振技术研究了在大肠杆菌中表达的dsRBD的结构，并借助一种新颖的计算策略得以解析。发现它具有α-β-β-β-α拓扑结构，其中一个三链反平行β折叠在一侧与两个螺旋堆积。对44个比对的dsRBD序列的研究揭示了几个保守的带正电荷的残基。这些残基位于第二个螺旋的N端和附近的一个环上，从而得出该结构域与双链RNA之间可能接触的模型。
