Catalytic-site mutations in the MYST family histone acetyltransferase ESA1
Catalytic-site mutations in the MYST family histone acetyltransferase ESA1
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DOI：
10.1534/genetics.107.080135
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发表时间：
2008-03-01
期刊：
影响因子：
3.3
通讯作者：
Smith, M. Mitchell
中科院分区：
文献类型：
--
作者：
Decker, Peter V.;Yu, David Y.;Smith, M. Mitchell
Esa1是芽殖酵母中唯一必需的组蛋白乙酰转移酶（HAT）。它是至少两种多蛋白复合物NuA4和Piccolo NuA4 （picNUA4）的催化亚基，其基本功能被认为是其催化HAT活性。为了研究Esa1在DNA损伤修复中的作用，我们通过Esa1突变体分离出一系列对拓扑糖苷喜树碱过敏的Esa1突变体。在这里，我们发现这些突变体对各种胁迫的敏感性与其组蛋白H4乙酰化水平成反比，证明了Esa1催化活性对基因毒性胁迫抗性的重要性。令人惊讶的是，即使突变酶在体内和体外都表现出催化活性，但直接参与催化的两个残基的个体突变并不致命。然而，双点突变体是致命的，这表明Esa1的基本功能依赖于催化口袋内的残基，而不是催化。我们认为Esa1的基本功能可能是结合乙酰辅酶a或赖氨酸底物，并积极调节NuA4和Piccolo NuA4的活性。
Esa1 is the only essential histone acetyltransferase (HAT) in budding yeast. It is the catalytic subunit of at least two multiprotein complexes, NuA4 and Piccolo NuA4 (picNUA4), and its essential function is believed to be its catalytic HAT activity. To examine the role of Esa1 in DNA damage repair, we isolated via esa1 mutants with a range of hypersensitivities to the toposide camptothecin. Here we show that the sensitivity of these mutants to a variety of stresses is inversely proportional to their level of histone H4 acetylation, demonstrating the importance of Esa1 catalytic activity for resistance to genotoxic stress. Surprisingly, individual mutations in two residues directly involved in catalysis were not lethal even though the mutant enzymes appear catalytically inactive both in vivo and in, vitro. However, the double-point mutant is lethal, demonstrating that the essential function of Esa1 relies on residues within the catalytic pocket but not catalysis. We propose that the essential function of Esa1 may be to bind acetyl-CoA or lysine substrates and Positively regulate the activities of NuA4 and Piccolo NuA4.