Extensive Functional Diversification of the Populus Glutathione S-Transferase Supergene Family
Extensive Functional Diversification of the Populus Glutathione S-Transferase Supergene Family
复制标题
杨谷胱甘肽 S-转移酶超基因家族的广泛功能多样化
DOI：
10.1105/tpc.109.070219
复制
发表时间：
2009-12-01
期刊：
影响因子：
11.6
通讯作者：
Zeng, Qing-Yin
中科院分区：
文献类型：
--
作者：
Lan, Ting;Yang, Zhi-Ling;Zeng, Qing-Yin
确定基因及其功能在复制后如何进化是理解基因家族辐射的核心。本研究综合系统发育、表达、底物专一性和酶动力学数据，系统研究了毛白杨谷胱甘肽S转移酶基因家族的功能多样性。GSTs是植物中普遍存在的一种蛋白质，在胁迫耐受和解毒代谢中发挥重要作用。基因组注释鉴定了81个杨树GST基因，这些基因在进化速度、基因结构、对非生物胁迫的表达响应以及编码蛋白的酶性质等方面存在明显的差异。此外，当检查所有功能参数时，在串联簇内和平行基因对之间观察到明显的差异，这表明重复基因之间发生了亚功能化。GST蛋白的这两个结构域似乎是在不同的选择压力下进化的。C-末端结构域似乎受到了更宽松的功能限制或不同的方向选择，这可能允许底物特异性、亲和力和活性的快速变化，同时保持酶的主要功能。我们的发现揭示了促进重复基因保留的机制，这可能导致一个大的基因家族，具有广泛的底物谱和对不同底物的广泛反应范围。
Identifying how genes and their functions evolve after duplication is central to understanding gene family radiation. In this study, we systematically examined the functional diversification of the glutathione S-transferase (GST) gene family in Populus trichocarpa by integrating phylogeny, expression, substrate specificity, and enzyme kinetic data. GSTs are ubiquitous proteins in plants that play important roles in stress tolerance and detoxification metabolism. Genome annotation identified 81 GST genes in Populus that were divided into eight classes with distinct divergence in their evolutionary rate, gene structure, expression responses to abiotic stressors, and enzymatic properties of encoded proteins. In addition, when all the functional parameters were examined, clear divergence was observed within tandem clusters and between paralogous gene pairs, suggesting that subfunctionalization has taken place among duplicate genes. The two domains of GST proteins appear to have evolved under differential selective pressures. The C-terminal domain seems to have been subject to more relaxed functional constraints or divergent directional selection, which may have allowed rapid changes in substrate specificity, affinity, and activity, while maintaining the primary function of the enzyme. Our findings shed light on mechanisms that facilitate the retention of duplicate genes, which can result in a large gene family with a broad substrate spectrum and a wide range of reactivity toward different substrates.