Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, Michigan 48824-4320, USA.
J Virol. 2011 Apr;85(7):3142-52. doi: 10.1128/JVI.02049-10. Epub 2011 Jan 26.
Human APOBEC3H (A3H) has one cytidine deaminase domain (CDD) and inhibits the replication of retrotransposons and human immunodeficiency virus type 1 (HIV-1) in a Vif-resistant manner. Human A3H has five single amino acid polymorphisms (N15Δ, R18L, G105R, K121D, and E178D), and four haplotypes (I to IV) have previously been identified in various human populations. Haplotype II was primarily found in African-derived populations, and it was the only one that could be stably expressed. Here, we identified three new haplotypes from six human population samples, which we have named V, VI, and VII. Haplotypes V and VII are stably expressed and inhibit HIV-1 replication. Notably, haplotype V was identified in samples from all African-, Asian-, and Caucasian-derived populations studied. Using haplotype VII, we investigated the A3H anti-HIV-1 mechanism. We found that A3H virion packaging is independent of its CDD but dependent on a (112)YYXW(115) motif. This motif binds HIV-1 nucleocapsid in an RNA-dependent manner, and a single Y112A mutation completely disrupts A3H virion incorporation. We further studied the mechanism of A3H resistance to Vif. Although the previously identified APOBEC3G Vif-responsive motif (128)DPDY(131) is not conserved in A3H, placement of this motif into A3H does not make it become less resistant to HIV-1 Vif. We conclude that stably expressed A3H haplotypes may be more broadly distributed in humans than previously realized, and A3H protein is resistant to Vif. These results have important implications for the role of A3H in retrotransposon and HIV-1 inhibition.
人 APOBEC3H(A3H)具有一个胞嘧啶脱氨酶结构域(CDD),并以 Vif 抗性的方式抑制逆转录转座子和人类免疫缺陷病毒 1(HIV-1)的复制。人 A3H 有五个单一氨基酸多态性(N15Δ、R18L、G105R、K121D 和 E178D),并且以前在各种人群中已经鉴定出四个单倍型(I 到 IV)。单倍型 II 主要存在于非洲裔人群中,并且是唯一可以稳定表达的单倍型。在这里,我们从六个人群样本中鉴定出三个新的单倍型,我们将其命名为 V、VI 和 VII。单倍型 V 和 VII 稳定表达并抑制 HIV-1 复制。值得注意的是,单倍型 V 存在于我们研究的所有非洲裔、亚洲裔和白种人群体的样本中。使用单倍型 VII,我们研究了 A3H 抗 HIV-1 的机制。我们发现 A3H 病毒包装与它的 CDD 无关,但依赖于一个(112)YYXW(115)基序。这个基序以 RNA 依赖的方式结合 HIV-1 核衣壳,并且单个 Y112A 突变完全破坏 A3H 病毒包装。我们进一步研究了 A3H 对 Vif 的抗性机制。尽管在 A3H 中没有保守的先前鉴定的 APOBEC3G Vif 反应性基序(128)DPDY(131),但将这个基序插入 A3H 并不会使其对 HIV-1 Vif 的抗性降低。我们得出结论,稳定表达的 A3H 单倍型可能比以前认为的在人类中更广泛分布,并且 A3H 蛋白对 Vif 有抗性。这些结果对 A3H 在逆转录转座子和 HIV-1 抑制中的作用具有重要意义。