Role of poly-proline motif in HIV-2 Vpx expression.

人类免疫缺陷病毒2型（HIV-2）携带一种辅助蛋白Vpx，该蛋白对病毒在天然靶细胞中的复制很重要。在其C-末端区域，有一个高度保守的聚脯氨酸基序（PPM），由7个连续的脯氨酸组成。我们已经证明PPM对于Vpx表达和病毒感染性至关重要。为了阐明这一观察的分子基础，我们分析了Vpx蛋白的表达与各种PPM突变的体内和体外系统。我们发现PPM中连续脯氨酸的数量和位置对Vpx的表达很重要，并证明PPM对有效的Vpx翻译至关重要。最后，我们研究了来自恒河猴的猴免疫缺陷病毒（SIVmac）的Vpx，它也有7个连续的脯氨酸，PPM依赖的表达。PPM中的多取代突变显著降低SIVmac Vpx的表达水平。

Human immunodeficiency virus type 2 (HIV-2) carries an accessory protein Vpx that is important for viral replication in natural target cells. In its C-terminal region, there is a highly conserved poly-proline motif (PPM) consisting of seven consecutive prolines. We have shown that PPM is critical for Vpx expression and viral infectivity. To elucidate the molecular basis underlying this observation, we analysed the expression of Vpx proteins with various PPM mutations by in vivo and in vitro systems. We found that the number and position of consecutive prolines in PPM are important for Vpx expression, and demonstrated that PPM is essential for efficient Vpx translation. Finally, we examined the Vpx of simian immunodeficiency virus from rhesus monkeys (SIVmac), which also has seven consecutive prolines, for PPM-dependent expression. A multi-substitution mutation in the PPM markedly reduced the expression level of SIVmac Vpx.