Bannister A J, Miska E A, Görlich D, Kouzarides T
Department of Pathology, Wellcome/CRC Institute, University of Cambridge, Cambridge, CB2 1QR, UK.
Curr Biol. 2000 Apr 20;10(8):467-70. doi: 10.1016/s0960-9822(00)00445-0.
Histone acetylases were originally identified because of their ability to acetylate histone substrates [1] [2] [3]. Acetylases can also target other proteins such as transcription factors [4] [5] [6] [7]. We asked whether the acetylase CREB-binding protein (CBP) could acetylate proteins not directly involved in transcription. A large panel of proteins, involved in a variety of cellular processes, were tested as substrates for recombinant CBP. This screen identified two proteins involved in nuclear import, Rch1 (human importin-alpha) and importin-alpha7, as targets for CBP. The acetylation site within Rch1 was mapped to a single residue, Lys22. By comparing the context of Lys22 with the sequences of other known substrates of CBP and the closely related acetylase p300, we identified G/SK (in the single-letter amino acid code) as a consensus acetylation motif. Mutagenesis of the glycine, as well as the lysine, severely impaired Rch1 acetylation, supporting the view that GK is part of a recognition motif for acetylation by CBP/p300. Using an antibody raised against an acetylated Rch1 peptide, we show that Rch1 was acetylated at Lys22 in vivo and that CBP or p300 could mediate this reaction. Lys22 lies within the binding site for a second nuclear import factor, importin-beta. Acetylation of Lys22 promoted interaction with importin-beta in vitro. Collectively, these results demonstrate that acetylation is not unique to proteins involved in transcription. Acetylation may regulate a variety of biological processes, including nuclear import.
组蛋白乙酰转移酶最初是因其能够乙酰化组蛋白底物而被鉴定出来的[1][2][3]。乙酰转移酶还可以作用于其他蛋白质，如转录因子[4][5][6][7]。我们研究了乙酰转移酶CREB结合蛋白（CBP）是否能乙酰化不直接参与转录的蛋白质。我们测试了一大组参与各种细胞过程的蛋白质作为重组CBP的底物。该筛选鉴定出两种参与核输入的蛋白质，Rch1（人类输入蛋白α）和输入蛋白α7，作为CBP的作用靶点。Rch1内的乙酰化位点被定位到单个残基，赖氨酸22。通过将赖氨酸22的上下文与CBP和密切相关的乙酰转移酶p300的其他已知底物序列进行比较，我们确定G/SK（单字母氨基酸代码）为共有乙酰化基序。甘氨酸以及赖氨酸的诱变严重损害了Rch1的乙酰化，支持了GK是CBP/p300乙酰化识别基序一部分的观点。使用针对乙酰化Rch1肽产生的抗体，我们表明Rch1在体内赖氨酸22处被乙酰化，并且CBP或p300可以介导该反应。赖氨酸22位于第二个核输入因子输入蛋白β的结合位点内。赖氨酸22的乙酰化促进了体外与输入蛋白β的相互作用。总的来说，这些结果表明乙酰化并非参与转录的蛋白质所特有。乙酰化可能调节多种生物过程，包括核输入。
