Pipal Alexandra, Goralik-Schramel Maria, Lusser Alexandra, Lanzanova Chiara, Sarg Bettina, Loidl Adele, Lindner Herbert, Rossi Vincenzo, Loidl Peter
Institute of Molecular Biology, University of Innsbruck, Medical School, A-6020 Innsbruck, Austria.
Plant Cell. 2003 Aug;15(8):1904-17. doi: 10.1105/tpc.013995.
A maize histone deacetylase gene was identified as a homolog of yeast Hda1. The predicted protein corresponds to a previously purified maize deacetylase that is active as a protein monomer with a molecular weight of 48,000 and is expressed in all tissues of germinating embryos. Hda1 is synthesized as an enzymatically inactive protein with an apparent molecular weight of 84,000 that is processed to the active 48-kD form by proteolytic removal of the C-terminal part, presumably via a 65-kD intermediate. The enzymatically inactive 84-kD protein also is part of a 300-kD protein complex of unknown function. The proteolytic cleavage of ZmHda1 is regulated during maize embryo germination in vivo. Expression of the recombinant full-length protein and the 48-kD form confirmed that only the smaller enzyme form is active as a histone deacetylase. In line with this finding, we show that the 48-kD protein is able to repress transcription efficiently in a reporter gene assay, whereas the full-length protein, including the C-terminal part, lacks full repression activity. This report on the processing of Hda1-p84 to enzymatically active Hda1-p48 demonstrates that proteolytic cleavage is a mechanism to regulate the function of Rpd3/Hda1-type histone deacetylases.
一个玉米组蛋白去乙酰化酶基因被鉴定为酵母Hda1的同源物。预测的蛋白质对应于一种先前纯化的玉米去乙酰化酶，它作为一种分子量为48,000的蛋白质单体具有活性，并在萌发胚的所有组织中表达。Hda1最初合成时是一种表观分子量为84,000的无酶活性蛋白质，通过蛋白水解去除C末端部分（可能经由一个65-kD的中间体）被加工成活性的48-kD形式。这种无酶活性的84-kD蛋白质也是一个功能未知的300-kD蛋白质复合物的一部分。ZmHda1的蛋白水解切割在玉米胚体内萌发过程中受到调控。重组全长蛋白和48-kD形式蛋白的表达证实只有较小的酶形式作为组蛋白去乙酰化酶具有活性。与这一发现一致，我们表明在报告基因检测中48-kD蛋白质能够有效地抑制转录，而包括C末端部分的全长蛋白质缺乏完全的抑制活性。这篇关于Hda1-p84加工成具有酶活性的Hda1-p48的报告表明蛋白水解切割是一种调节Rpd3/Hda1型组蛋白去乙酰化酶功能的机制。
