Echarri A, González M E, Carrasco L
Centro de Biología Molecular CSIC-UAM, Universidad Autónoma de Madrid, Spain.
Eur J Biochem. 1997 May 15;246(1):38-44. doi: 10.1111/j.1432-1033.1997.00038.x.
Comparison of the amino acid sequences of human immunodeficiency virus (HIV) Nef protein and several RNA-binding proteins shows similarities in some regions of these proteins. Thus, poliovirus protein 2C, an RNA-binding protein, shares with Nef the sequence YXQQ...MDD...DXXD. In addition, both proteins contain an Arg-rich motif that, in the case of poliovirus 2C, is involved in RNA-binding activity. Moreover, the RNA-binding, anti-terminator N proteins of lambda, phi21 and P22 phages show sequence similarities with HIV Nef at the Arg-rich motif. To assess the significance of this motif, native and deletion variants of Nef protein were assayed for RNA-binding activity. The N-terminal 35 amino acids of HIV-1 Nef that comprise the Arg-rich motif are sufficient for RNA binding. Point mutations engineered at the Arg-rich motif of HIV-1 Nef revealed that basic amino acid residues are essential for RNA-binding activity. The Nef proteins from HIV-2 and SIV can also interact with RNA, while the same proteins with the N-terminal Arg-rich domain truncated fail to interact with RNA. These findings indicate that all three Nef proteins from HIV-1, HIV-2 and simian immunodeficiency virus belong to the RNA-binding family of proteins. The three proteins contain an Arg-rich region at the N-terminus which is necessary to interact with RNA.
人类免疫缺陷病毒（HIV）Nef蛋白与几种RNA结合蛋白的氨基酸序列比较显示，这些蛋白的某些区域存在相似性。因此，作为一种RNA结合蛋白的脊髓灰质炎病毒蛋白2C与Nef共有序列YXQQ...MDD...DXXD。此外，这两种蛋白都含有一个富含精氨酸的基序，就脊髓灰质炎病毒2C而言，该基序参与RNA结合活性。此外，λ噬菌体、φ21噬菌体和P22噬菌体的RNA结合抗终止子N蛋白在富含精氨酸的基序处与HIV Nef显示出序列相似性。为了评估该基序的重要性，对Nef蛋白的天然变体和缺失变体进行了RNA结合活性检测。HIV-1 Nef包含富含精氨酸基序的N端35个氨基酸足以进行RNA结合。在HIV-1 Nef富含精氨酸的基序处设计的点突变表明，碱性氨基酸残基对于RNA结合活性至关重要。来自HIV-2和猴免疫缺陷病毒的Nef蛋白也能与RNA相互作用，而截短了N端富含精氨酸结构域的相同蛋白则无法与RNA相互作用。这些发现表明，来自HIV-1、HIV-2和猴免疫缺陷病毒的所有三种Nef蛋白都属于RNA结合蛋白家族。这三种蛋白在N端含有一个富含精氨酸的区域，该区域是与RNA相互作用所必需的。
