Antson A A, Dodson E J, Dodson G, Greaves R B, Chen X, Gollnick P
York Structural Biology Laboratory, Department of Chemistry, University of York, UK.
Nature. 1999 Sep 16;401(6750):235-42. doi: 10.1038/45730.
The trp RNA-binding attenuation protein (TRAP) regulates expression of the tryptophan biosynthetic genes of several bacilli by binding single-stranded RNA. The binding sequence is composed of eleven triplet repeats, predominantly GAG, separated by two or three non-conserved nucleotides. Here we present the crystal structure of a complex of TRAP and a 53-base single-stranded RNA containing eleven GAG triplets, revealing that each triplet is accommodated in a binding pocket formed by beta-strands. In the complex, the RNA has an extended structure without any base-pairing and binds to the protein mostly by specific protein-base interactions. Eleven binding pockets on the circular TRAP 11-mer form a belt with a diameter of about 80 A. This simple but elegant mechanism of arresting the RNA segment by encircling it around a protein disk is applicable to both transcription, when TRAP binds the nascent RNA, and to translation, when TRAP binds the same sequence within a non-coding leader region of the messenger RNA.
色氨酸RNA结合衰减蛋白（TRAP）通过结合单链RNA来调控几种芽孢杆菌中色氨酸生物合成基因的表达。结合序列由11个三联体重复序列组成，主要为GAG，中间间隔两三个非保守核苷酸。本文展示了TRAP与一段含有11个GAG三联体的53个碱基的单链RNA复合物的晶体结构，揭示出每个三联体都容纳在由β链形成的结合口袋中。在该复合物中，RNA呈伸展结构，没有任何碱基配对，并且主要通过特定的蛋白质-碱基相互作用与蛋白质结合。环状TRAP 11聚体上的11个结合口袋形成了一个直径约为80埃的环带。这种通过围绕蛋白质盘环绕来捕获RNA片段的简单而精妙的机制，既适用于TRAP结合新生RNA时的转录过程，也适用于TRAP结合信使RNA非编码前导区内相同序列时的翻译过程。
