Batey R T, Sagar M B, Doudna J A
Department of Molecular Biophysics and Biochemistry and Howard Hughes Medical Institute, Yale University, P.O. Box 208114, New Haven, CT 06520-8814, USA.
J Mol Biol. 2001 Mar 16;307(1):229-46. doi: 10.1006/jmbi.2000.4454.
The signal recognition particle (SRP) is a ribonucleoprotein complex responsible for targeting proteins to the endoplasmic reticulum in eukarya or to the inner membrane in prokarya. The crystal structure of the universally conserved RNA-protein core of the Escherichia coli SRP, refined here to 1.5 A resolution, revealed minor groove recognition of the 4.5 S RNA component by the M domain of the Ffh protein. Within the RNA, nucleotides comprising two phylogenetically conserved internal loops create a unique surface for protein recognition. To determine the energetic importance of conserved nucleotides for SRP assembly, we measured the affinity of the M domain for a series of RNA mutants. This analysis reveals how conserved nucleotides within the two internal loop motifs establish the architecture of the macromolecular interface and position essential functional groups for direct recognition by the protein.
信号识别颗粒（SRP）是一种核糖核蛋白复合体，负责将真核生物中的蛋白质靶向内质网或原核生物中的内膜。大肠杆菌SRP普遍保守的RNA-蛋白质核心的晶体结构在此处精修至1.5埃分辨率，揭示了Ffh蛋白的M结构域对4.5 S RNA组分的小沟识别。在RNA内，构成两个系统发育保守内部环的核苷酸形成了独特的蛋白质识别表面。为了确定保守核苷酸对SRP组装的能量重要性，我们测量了M结构域对一系列RNA突变体的亲和力。该分析揭示了两个内部环基序内的保守核苷酸如何建立大分子界面的结构并定位必需的功能基团以供蛋白质直接识别。
