Institute of Advanced Energy, Graduate School of Energy Science, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan).
Angew Chem Int Ed Engl. 2014 Feb 24;53(9):2349-52. doi: 10.1002/anie.201309940. Epub 2014 Jan 29.
The human antiretroviral factor APOBEC3G (A3G) deaminates the newly synthesized minus strand of the human immunodeficiency virus 1 (HIV-1), which results in the abolition of the infectivity of virus-infectivity-factor (Vif)-deficient HIV-1 strains.1-6 A unique property of A3G is that it deaminates a CCC hot spot that is located close to the 5' end more effectively than one that is less close to the 5' end. However, the mechanism of this process is elusive as it includes nonspecific binding of A3G to DNA and sliding of A3G along the DNA strand. Therefore, this process cannot be analyzed by existing methods using the Michaelis-Menten theory. A new real-time NMR method has been developed to examine the nonspecific binding and the sliding processes explicitly, and it was applied to the analysis of the deamination by A3G. As a result, the location-dependent deamination can be explained by a difference in the catalytic rates that depend on the direction of the approach of A3G to the target cytidine. Real-time NMR experiments also showed that A3G deaminates CCCC tandem hotspots with little redundancy, which suggests that A3G efficiently mutates many CCC hotspots that are scattered throughout the HIV-1 genome.
人类抗病毒因子 APOBEC3G（A3G）使人类免疫缺陷病毒 1（HIV-1）新合成的负链脱氨酶化，导致缺乏病毒感染因子（Vif）的 HIV-1 株的感染力丧失。1-6 A3G 的一个独特特性是，它更有效地脱氨靠近 5'端的 CCC 热点，而不是不太靠近 5'端的热点。然而，由于 A3G 与 DNA 的非特异性结合以及 A3G 在 DNA 链上的滑动，该过程的机制尚不清楚。因此，现有的米氏理论分析方法无法分析该过程。已经开发了一种新的实时 NMR 方法来明确检查非特异性结合和滑动过程，并将其应用于 A3G 的脱氨分析。结果表明，依赖于 A3G 接近靶胞嘧啶方向的催化速率的差异，可以解释位置依赖性脱氨。实时 NMR 实验还表明，A3G 以很少的冗余脱氨 CCCC 串联热点，这表明 A3G 有效地突变了散布在 HIV-1 基因组中的许多 CCC 热点。
