Saleh Abdelaty, Alvarez-Venegas Raul, Yilmaz Mehtap, Le Oahn, Hou Guichuan, Sadder Monther, Al-Abdallat Ayed, Xia Yuannan, Lu Guoqinq, Ladunga Istvan, Avramova Zoya
School of Biological Sciences, University of Nebraska, Lincoln, Nebraska 68588-0118, USA.
Plant Cell. 2008 Mar;20(3):568-79. doi: 10.1105/tpc.107.056614. Epub 2008 Mar 28.
Gene duplication followed by functional specialization is a potent force in the evolution of biological diversity. A comparative study of two highly conserved duplicated genes, ARABIDOPSIS TRITHORAX-LIKE PROTEIN1 (ATX1) and ATX2, revealed features of both partial redundancy and of functional divergence. Although structurally similar, their regulatory sequences have diverged, resulting in distinct temporal and spatial patterns of expression of the ATX1 and ATX2 genes. We found that ATX2 methylates only a limited fraction of nucleosomes and that ATX1 and ATX2 influence the expression of largely nonoverlapping gene sets. Even when coregulating shared targets, ATX1 and ATX2 may employ different mechanisms. Most remarkable is the divergence of their biochemical activities: both proteins methylate K4 of histone H3, but while ATX1 trimethylates it, ATX2 dimethylates it. ATX2 and ATX1 provide an example of separated K4 di from K4 trimethyltransferase activity.
基因复制后伴随功能特化是生物多样性进化中的一股强大力量。对两个高度保守的复制基因拟南芥类三体同源蛋白1（ATX1）和ATX2的比较研究揭示了部分冗余和功能分化的特征。尽管它们在结构上相似，但其调控序列已经发生分歧，导致ATX1和ATX2基因在时间和空间上呈现出不同的表达模式。我们发现ATX2仅使有限比例的核小体发生甲基化，并且ATX1和ATX2影响的基因集在很大程度上不重叠。即使在共同调控共享靶标时，ATX1和ATX2也可能采用不同的机制。最显著的是它们生化活性的差异：两种蛋白质都使组蛋白H3的K4发生甲基化，但ATX1使其三甲基化，而ATX2使其二甲基化。ATX2和ATX1提供了一个K4二甲基转移酶活性与K4三甲基转移酶活性分离的例子。
