CIRCULAR-DICHROISM AND MOLECULAR MODELING YIELD A STRUCTURE FOR THE COMPLEX OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 TRANSACTIVATION RESPONSE RNA AND THE BINDING REGION OF TAT, THE TRANS-ACTING TRANSCRIPTIONAL ACTIVATOR
CIRCULAR-DICHROISM AND MOLECULAR MODELING YIELD A STRUCTURE FOR THE COMPLEX OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1 TRANSACTIVATION RESPONSE RNA AND THE BINDING REGION OF TAT, THE TRANS-ACTING TRANSCRIPTIONAL ACTIVATOR
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DOI：
10.1073/pnas.89.20.9734
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发表时间：
1992-10-15
影响因子：
11.1
通讯作者：
HO, PS
中科院分区：
文献类型：
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作者：
LORET, EP;GEORGEL, P;HO, PS
人类免疫缺陷病毒1型(HIV-1)逆转录病毒的转录是通过将病毒Tat蛋白(反式作用转录激活因子)与反式激活反应(TAR)RNA序列结合来调节的。本文用真空紫外圆二色谱(VUV-CD)研究了焦油及其与TAT结合的两个重要多肽片段的结构。焦油的VUV-CD光谱是典型的A-型RNA，当与短的或长的TAT肽结合时，受到的干扰最小。CD谱表明，在TAT的精氨酸富集区，从氨基酸残基47到残基58有一个延伸的结构，在邻近的59-72区域有一个短的α-螺旋。构建了焦油及其多肽络合物的模型，以将这些光谱结果与当前的生化数据相结合。该模型表明：(I)富含精氨酸的49-58区域主要负责与RNA磷酸盐的静电相互作用，(Ii)精氨酸侧链还可以与核苷酸碱基的取代基相互作用，从而在复合体中实现碱基识别，(Iii)肽骨架促进了对焦油中uracil-23的识别，以及(Iv)59-72区域对中富含谷氨酰胺的α-螺旋的面与焦油环中31-33位的碱基UGG相连，从而在TAT反式激活蛋白中提供了一个额外的基序来识别TAR RNA。
Transcription in the human immunodeficiency virus type 1 (HIV-1) retrovirus is regulated by binding the viral Tat protein (trans-acting transcriptional activator) to the trans-activation response (TAR) RNA sequence. Here, vacuum UV circular dichroism (VUV-CD) is used to study the structure of TAR and its complex with two peptide fragments that are important for Tat binding to TAR. The VUV-CD spectrum of TAR is typical of A-form RNA and is minimally perturbed when bound to either the short or the long Tat peptide. The CD spectra of the complexes indicate an extended structure in the arginine-rich region of Tat from amino acid residue 47 through residue 58 and a short alpha-helix within the adjacent 59-72 region. Models of TAR and its peptide complexes are constructed to integrate these spectroscopic results with current biochemical data. The model suggests that (i) the arginine-rich 49-58 region is primarily responsible for electrostatic interactions with the phosphates of the RNA, (ii) the arginine side chains can additionally interact with substituent groups of the nucleotide bases to confer base recognition in the complex, (iii) the recognition of uracil-23 in TAR is facilitated by the peptide backbone, and (iv) the glutamine-rich face of an alpha-helix within the 59-72 region pairs to bases UGG at nucleotide positions 31-33 in the TAR loop and thus provides an additional motif in the Tat trans-activating protein to recognize TAR RNA.