Lau Chi-kong, Bachorik Jennifer L, Dreyfuss Gideon
Howard Hughes Medical Institute and Department of Biochemistry and Biophysics, University of Pennsylvania School of Medicine, Philadelphia, USA.
Nat Struct Mol Biol. 2009 May;16(5):486-91. doi: 10.1038/nsmb.1584. Epub 2009 Apr 19.
Gemin5 binds specifically to the small nuclear RNA (snRNA)-defining small nuclear ribonucleoprotein (snRNP) code sequence and is essential, together with other components of the survival of motor neurons (SMN) complex, for the biogenesis of snRNPs, the major constituents of spliceosomes. We show that this binding is mediated by Gemin5's WD repeat domain, a common domain not previously known to bind RNA independently. The entire WD repeat domain, comprising 13 WD motifs, is both necessary and sufficient for sequence-specific, high-affinity binding of Gemin5 to its RNA targets. Using an RNA-mediated hydroxyl radical probing method and mass spectrometry, we mapped a discrete region of the WD repeat domain that contacts snRNAs and demonstrated by mutagenesis that specific amino acids in this region are crucial for Gemin5-snRNA binding. The WD repeat domain is thus a previously undescribed RNA binding domain, and we suggest that the presence of WD repeats should be considered as predictive of potential function in RNA binding.
Gemin5特异性结合定义小核RNA（snRNA）的小核核糖核蛋白（snRNP）编码序列，并且与运动神经元存活（SMN）复合体的其他组分一起，对于剪接体的主要成分snRNP的生物合成至关重要。我们表明，这种结合由Gemin5的WD重复结构域介导，这是一个以前未知能独立结合RNA的常见结构域。由13个WD基序组成的整个WD重复结构域对于Gemin5与其RNA靶标的序列特异性、高亲和力结合而言既是必需的也是足够的。使用RNA介导的羟自由基探测方法和质谱分析，我们绘制了WD重复结构域中与snRNA接触的离散区域，并通过诱变证明该区域中的特定氨基酸对于Gemin5与snRNA的结合至关重要。因此，WD重复结构域是一个以前未描述的RNA结合结构域，并且我们建议应将WD重复的存在视为预测RNA结合潜在功能的依据。
