Bycroft M, Grünert S, Murzin A G, Proctor M, St Johnston D
Cambridge Centre for Protein Engineering, Department of Chemistry, University of Cambridge, UK.
EMBO J. 1995 Jul 17;14(14):3563-71. doi: 10.1002/j.1460-2075.1995.tb07362.x.
The double-stranded RNA binding domain (dsRBD) is an approximately 65 amino acid motif that is found in a variety of proteins that interact with double-stranded (ds) RNA, such as Escherichia coli RNase III and the dsRNA-dependent kinase, PKR. Drosophila staufen protein contains five copies of this motif, and the third of these binds dsRNA in vitro. Using multinuclear/multidimensional NMR methods, we have determined that staufen dsRBD3 forms a compact protein domain with an alpha-beta-beta-beta-alpha structure in which the two alpha-helices lie on one face of a three-stranded anti-parallel beta-sheet. This structure is very similar to that of the N-terminal domain of a prokaryotic ribosomal protein S5. Furthermore, the consensus derived from all known S5p family sequences shares several conserved residues with the dsRBD consensus sequence, indicating that the two domains share a common evolutionary origin. Using in vitro mutagenesis, we have identified several surface residues which are important for the RNA binding of the dsRBD, and these all lie on the same side of the domain. Two residues that are essential for RNA binding, F32 and K50, are also conserved in the S5 protein family, suggesting that the two domains interact with RNA in a similar way.
双链RNA结合结构域（dsRBD）是一个约65个氨基酸的基序，存在于多种与双链（ds）RNA相互作用的蛋白质中，如大肠杆菌核糖核酸酶III和dsRNA依赖性激酶PKR。果蝇staufen蛋白含有该基序的五个拷贝，其中第三个拷贝在体外可结合dsRNA。利用多核/多维核磁共振方法，我们确定staufen dsRBD3形成了一个紧密的蛋白质结构域，具有α-β-β-β-α结构，其中两个α-螺旋位于一个三链反平行β-折叠的一侧。这种结构与原核核糖体蛋白S5的N端结构域非常相似。此外，从所有已知的S5p家族序列推导的共有序列与dsRBD共有序列共享几个保守残基，表明这两个结构域具有共同的进化起源。利用体外诱变，我们鉴定了几个对dsRBD的RNA结合很重要的表面残基，这些残基都位于结构域的同一侧。对RNA结合至关重要的两个残基F32和K50在S5蛋白家族中也保守，这表明这两个结构域以相似的方式与RNA相互作用。
