Mature HIV-1 protease (PR) functions as a dimer. Changes in HIV-1 PR activation can block virus assembly via premature or enhanced Gag cleavage. HIV-1 PR precursor contains N terminal-linked p6*, a possible modulating factor in PR activation. We found that p6* replacement with a leucine zipper (LZ) dimerization motif (creating a DWzPR construct) or an LZ insertion at the PR C-terminus significantly reduced virus yields due to enhanced Gag cleavage, suggesting that an LZ insertion promotes PR activation by facilitating PR dimer formation. However, introducing T26S (a PR activity-attenuated mutation) into DWzPR strongly impaired Gag cleavage, except when the native C-terminal p6* tetrapeptide remained at the LZ/PR junction. LZ insertion at the PR C-terminus still strongly enhanced PR T26S Gag cleavage. Our data suggest that in addition to p6* mutations, a single amino acid substitution within PR can impair PR activation, likely due to conformational changes triggered by the PR precursor.

成熟的 HIV-1 蛋白酶 (PR) 作为二聚体发挥作用。HIV-1 PR 激活的变化可以通过过早或增强的 Gag 裂解来阻止病毒组装。HIV-1 PR 前体含有 N 末端连接的 p6*，这是 PR 激活中可能的调节因子。我们发现用亮氨酸拉链 (LZ) 二聚化基序替换 p6*（创建 DWzPR 构建体）或在 PR C 末端插入 LZ 会由于 Gag 切割增强而显着降低病毒产量，这表明 LZ 插入通过以下方式促进 PR 激活促进 PR 二聚体的形成。然而，将 T26S（PR 活性减弱突变）引入 DWzPR 会严重损害 Gag 切割，除非天然 C 末端 p6* 四肽保留在 LZ/PR 连接处。在 PR C 末端插入 LZ 仍然强烈增强 PR T26S Gag 切割。