Sir2: An NAD-dependent histone deacetylase that connects chromatin silencing, metabolism, and aging
Sir2: An NAD-dependent histone deacetylase that connects chromatin silencing, metabolism, and aging
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DOI：
10.1101/sqb.2000.65.297
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发表时间：
2000-01-01
期刊：
影响因子：
--
通讯作者：
Guarente, L
中科院分区：
文献类型：
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作者：
Imai, S;Johnson, FB;Guarente, L
在体外ADP-核糖基化反应条件下，NAD浓度约为几微摩尔，检测不到Sir2的脱乙酰酶活性(Imai et al. 2000)。然而，随着 NAD 浓度的增加，Sir2 酶活性的模式似乎从 ADP-核糖基转移酶转变为 NAD 依赖性脱乙酰酶。在 100 μM 至 1 mM 范围内，Sir2 可以明显使 H3 的 Lys-9 和 Lys-14，特别是 H4 的 Lys-16 脱乙酰（Imai et al. 2000）。在此反应中，NADH、NADP 或 NADPH 不能替代 NAD。这是真核生物中第一个 NAD 驱动不同于普通氧化/还原反应的酶促反应的例子。这种 NAD 依赖性脱乙酰活性在酵母和小鼠 Sir2 之间也高度保守（Imai 等人，2000）。在这些反应下，高压液相色谱和质谱法未检测到 ADP-核糖基化产物（数据未显示）。最近，据报道，NAD 依赖性脱乙酰酶活性在从细菌到人类的多种生物体的 Sir2 家族成员中是保守的（Landry 等人，2000 年；Smith 等人，2000 年）。由于其中一些位于细胞质中（Afshar 和 Murnane 1999；Smith 等人 2000），因此这种活性在不同的生物环境中可能具有更普遍的重要性。
Under the condition of ADP-ribosylation reaction in vitro, NAD concentration is approximately a few micromolar and the deacetylase activity of Sir2 is not detectable (Imai et al. 2000). As NAD concentration is increased, however, the mode of Sir2 enzymatic activity seems to be shifted from ADP-ribosyltransferase to NAD-dependent deacetylase. In the range from 100 μM to 1 mM, Sir2 can clearly deacetylate Lys-9 and Lys-14 of H3 and specifically Lys-16 of H4 (Imai et al. 2000). NADH, NADP, or NADPH cannot substitute for NAD in this reaction. This is the first example in eukaryotes in which NAD drives an enzymatic reaction distinct from ordinary oxidation/reduction reactions. This NAD-dependent deacetylation activity is also highly conserved between yeast and mouse Sir2 (Imai et al. 2000). Under these reactions, no ADP-ribosylated products were detected by high-pressure liquid chromatography and mass spectroscopy (data not shown). Recently, it was reported that the NAD-dependent deacetylase activity is conserved among Sir2 family members in a wide variety of organisms, from bacteria to humans (Landry et al. 2000; Smith et al. 2000). Since some of them localize in the cytoplasm (Afshar and Murnane 1999; Smith et al. 2000), this activity may have more general importance in different biological contexts.