Servet Caroline, Benhamed Moussa, Latrasse David, Kim Wanhui, Delarue Marianne, Zhou Dao-Xiu
Institut de Biotechnologie des Plantes, CNRS UMR8618, Université Paris sud 11, 91405 Orsay, France.
Biochim Biophys Acta. 2008 Jun-Jul;1779(6-7):376-82. doi: 10.1016/j.bbagrm.2008.04.007. Epub 2008 May 2.
Arabidopsis GCN5 is a major histone acetyltransferase. The mutation of the gene induces pleiotropic effects on plant development, and affects the expression of a large number of genes. The mechanism of action of this protein in controlling plant chromatin structure and genome expression is not understood. In this work, we report the identification of a number of potential protein interacting partners of GCN5 in Arabidopsis. In particular, GCN5 was shown to interact specifically with a phosphatase 2C protein (AtPP2C-6-6). GCN5 phosphorylated by activities in cellular extracts could be dephosphorylated by AtPP2C-6-6 in vitro. Analysis of T-DNA insertion mutants revealed a positive role of AtPP2C-6-6 in salt induction of stress-inducible genes, while the gcn5 mutation seemed to have no effect on the induction but showed up-regulation of a subset of the stress-inducible genes under non-induced conditions. In addition, the gcn5 mutation seriously reduced acetylation of histone H3K14 and H3K27, whereas the T-DNA insertions of the AtPP2C6-6 gene enhanced the acetylation of these lysine residues. Taken together, the present data suggest that AtPP2C-6-6 may function as a negative regulator of GCN5 activity in Arabidopsis.
拟南芥GCN5是一种主要的组蛋白乙酰转移酶。该基因的突变对植物发育产生多效性影响，并影响大量基因的表达。目前尚不清楚这种蛋白质在控制植物染色质结构和基因组表达中的作用机制。在这项研究中，我们报告了在拟南芥中鉴定出一些GCN5潜在的蛋白质相互作用伙伴。特别地，GCN5被证明与一种磷酸酶2C蛋白（AtPP2C-6-6）特异性相互作用。在细胞提取物中被磷酸化的GCN5在体外可被AtPP2C-6-6去磷酸化。对T-DNA插入突变体的分析揭示了AtPP2C-6-6在盐诱导胁迫诱导基因方面的积极作用，而gcn5突变似乎对诱导没有影响，但在非诱导条件下显示出一部分胁迫诱导基因的上调。此外，gcn5突变严重降低了组蛋白H3K14和H3K27的乙酰化，而AtPP2C6-6基因的T-DNA插入增强了这些赖氨酸残基的乙酰化。综上所述，目前的数据表明AtPP2C-6-6可能作为拟南芥中GCN5活性的负调节因子发挥作用。
