Chang Y N, Kenan D J, Keene J D, Gatignol A, Jeang K T
Molecular Virology Section, National Institute of Allergy and Infectious Diseases, NIH, Bethesda, MD 20892.
J Virol. 1994 Nov;68(11):7008-20. doi: 10.1128/JVI.68.11.7008-7020.1994.
We have characterized the in vivo and in vitro binding of human La protein to the human immunodeficiency virus type 1 (HIV-1) leader RNA, the trans-activation response element (TAR). In immunoprecipitation studies using anti-La serum, La-TAR ribonucleoproteins were recovered from HIV-1-infected lymphocytes. Further characterization of this interaction revealed that La has preference for the TAR stem. However, TAR RNA recognition tolerated changes in the primary sequence of the stem as long as the secondary structure was conserved. This structural aspect of La-TAR recognition was confirmed in competition studies in which certain homopolymers influenced complex formation while other single-stranded and double-stranded RNAs had no effect. Deletion mutants of recombinant La protein were used to demonstrate that the residues responsible for binding to polymerase III precursor transcripts overlapped the binding domain for the TAR leader RNA. This finding of a direct interaction between La and TAR has functional implications for translational regulation of HIV-1 mRNAs as demonstrated in the accompanying report (Y. V. Svitkin, A. Pause, and N. Sonenberg, J. Virol. 68:7001-7007, 1994).
我们已经对人La蛋白与人免疫缺陷病毒1型（HIV-1）前导RNA即反式激活应答元件（TAR）的体内和体外结合进行了表征。在使用抗La血清的免疫沉淀研究中，从HIV-1感染的淋巴细胞中回收了La-TAR核糖核蛋白。对这种相互作用的进一步表征表明，La对TAR茎有偏好。然而，只要二级结构保守，TAR RNA识别就能容忍茎一级序列的变化。在竞争研究中证实了La-TAR识别的这一结构方面，其中某些同聚物影响复合物形成，而其他单链和双链RNA则没有影响。重组La蛋白的缺失突变体用于证明与聚合酶III前体转录本结合的残基与TAR前导RNA的结合域重叠。如随附报告（Y.V.Svitkin、A.Pause和N.Sonenberg，《病毒学杂志》68:7001-7007，1994）所示，La与TAR之间直接相互作用的这一发现对HIV-1 mRNA的翻译调控具有功能意义。
