中国科学院遗传与发育所发现组蛋白密码“阅读者”调控植物耐逆分子机制

中国科学院遗传与发育生物学研究所陈受宜和张劲松研究组从大豆中鉴定出一个特殊的 PHD 锌指蛋白——GmPHD6。它属于 PHD 中的 Alfin 亚类，Alfin 亚类普遍具有转录抑制能力，而 GmPHD6 例外。该研究发现 GmPHD6 必须与 LHP1（类异染色质蛋白）相互作用，并依赖 LHP1 的转录激活能力，调控下游耐盐基因的表达。

PHD 锌指蛋白又被称为组蛋白密码的“阅读者”，因为 PHD 结构域识别不同修饰的组蛋白 H3。GmPHD6 识别 H3K4me0/1/2，但并不通过 PHD 结构域，而是通过其 N 端，这又是其与众不同之处。此外，GmPHD6 的 N 端还能识别下游基因的启动子。而 PHD 结构域负责与 LHP1 的相互作用。

基于以上发现，研究人员总结出 GmPHD6 的分子调控模型：H3K4me0/1/ 2 可能与植物逆境调控关联，它们招募 GmPHD6，而 GmPHD6 招募 LHP1 形成转录调控复合体。复合体通过 GmPHD6 靶定下游基因，通过 LHP1 激活下游基因表达，从而提高植物的耐逆能力。

该研究是 PHD 锌指蛋白调控机制的重要补充，为改善作物耐逆性提供了重要的理论依据。该研究于 9 月 5 日在线发表于 Plant Physiology (DOI: 10.1104/pp.16.01764.)。研究组工作人员韦伟为该论文第一作者。该项研究受到了科技部、农业部、国家自然科学基金委和植物基因组学国家重点实验室等的资助。（来源：中国科学院遗传与发育生物学研究所）

A histone code reader and a transcriptional activator interact to regulate genes for salt tolerance

Abstract Plant homeodomain (PHD) finger proteins are involved in various developmental processes and stress responses. They recognize and bind to epigenetically modified histone H3 \&\#39\;tail\&\#39\; and function as \&\#39\;histone code readers\&\#39\;. Here we report that GmPHD6 reads low methylated histone H3K4me0/1/2 but not H3K4me3 with its N-terminal domain instead of the PHD finger. GmPHD6 does not possess transcriptional regulatory ability but has DNA-binding ability. Through the PHD finger, GmPHD6 interacts with its co-activator, LHP1-1/2 to form a transcriptional activation complex. Using a transgenic hairy root system, we demonstrate that over-expression of GmPHD6 improves stress tolerance in soybean plants. Knocking down the LHP1 expression disrupts this role of GmPHD6, indicating that GmPHD6 requires LHP1 functions during stress response. GmPHD6 influences expression of dozens of stress-related genes. Among these, we identified three targets of GmPHD6, including ASR (ABA-stress-ripening induced), CYP75B1 and CYP82C4. Overexpression of each gene confers stress tolerance in soybean plants. GmPHD6 is recruited to H3K4me0/1/2 marks and recognizes the G-rich elements in target gene promoters，while LHP1 activates expression of these targets. Our study reveals a mechanism involving two partners in a complex. Manipulation of the genes in this pathway should improve stress tolerance in soybean or other legumes/crops.

原文链接：http://www.plantphysiol.org/content/plantphysiol/early/2017/09/05/pp.16.01764.full.pdf