The PHD finger of Arabidopsis SIZ1 recognizes trimethylated histone H3K4 mediating SIZ1 function and abiotic stress response

First author: Kenji Miura; Affiliations: University of Tsukuba (筑波大学): Tsukuba, Japan

Corresponding author: Kenji Miura

Arabidopsis SIZ1 encodes a SUMO E3 ligase to regulate abiotic and biotic stress responses. Among SIZ1 or mammalian PIAS orthologs, plant SIZ1 proteins contain the plant homeodomain (PHD) finger, a C4HC3 zinc finger. Here, we investigated the importance of PHD of Arabidopsis SIZ1. The ProSIZ1::SIZ1(ΔPHD):GFP was unable to complement growth retardation, ABA hypersensitivity, and the cold-sensitive phenotype of the siz1 mutant, but ProSIZ1::SIZ1:GFP could. Substitution of C162S in the PHD finger was unable to complement the siz1 mutation. Tri-methylated histone H3K4 (H3K4me3) was recognized by PHD, not by PHD(C162S). WRKY70 was up-regulated in the siz1-2 mutant and H3K4me3 accumulated at high levels in the WRKY70 promoter. PHD interacts with ATX, which mediates methylation of histone, probably leading to suppression of ATX’s function. These results suggest that the PHD finger of SIZ1 is important for recognition of the histone code and is required for SIZ1 function and transcriptional suppression.

拟南芥的SIZ1编码一个SUMO E3连接酶，调控生物和非生物胁迫响应。在SIZ1或哺乳动物PIAS的同源蛋白中，植物的SIZ1蛋白包含一个植物同源结构域PHD指，一个C4HC3锌指。本文中，作者研究了拟南芥SIZ1蛋白中PHD的重要性。ProSIZ1::SIZ1(ΔPHD):GFP并不能互补siz1突变体的生长迟缓、ABA超敏感以及低温敏感表型，但是ProSIZ1::SIZ1:GFP可以。将PHD指中的162位的C替换成S就不能互补siz1突变体的缺陷表型。PHD能够识别三甲基化组蛋白H3K4me3，但PHD(C162S)不能。siz1-2突变体中WRKY70基因的表达显著上调，并且WRKY70启动子上的H3K4me3沉积水平较高。PHD能够与ATX互作，而ATX介导组蛋白的甲基化，因此SIZ1蛋白可能会抑制ATX的功能。本文的结果揭示了SIZ1蛋白的PHD指对于组蛋白的识别非常重要，同时对于SIZ1的功能以及转录抑制也很重要。

通讯：Kenji Miura（http://www.global.tsukuba.ac.jp/people/kenji-miura）

个人简介：2012年，京都大学，博士。

研究方向：植物冷信号转导分子机制；植物组织中的过敏原。

doi: https://doi.org/10.1038/s42003-019-0746-2

Journal: Communications Biology

Published date: January 10, 2020