The Arabidopsis SUMO E3 ligase SIZ1 controls phosphate deficiency responses
The Arabidopsis SUMO E3 ligase SIZ1 controls phosphate deficiency responses
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DOI：
10.1073/pnas.0500778102
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发表时间：
2005-05-24
影响因子：
11.1
通讯作者：
Hasegawa, PM
中科院分区：
文献类型：
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作者：
Miura, K;Rus, A;Hasegawa, PM
植物感知磷酸盐（Pi）缺乏并启动信号传导，控制Pi获取所需的适应性反应。在此，有证据表明AtSIZ 1是植物小泛素样修饰剂（SUMO）E3连接酶，是Pi饥饿依赖性反应的焦点控制器。AtSIZ 1（At 5g 60410）的T-DNA插入突变等位基因导致拟南芥表现出夸张的原型磷饥饿反应，包括停止主根生长，广泛的侧根和根毛发育，根/冠质量比增加，和更大的花青素积累，即使在siz 1植物细胞内的磷水平与野生型相似。AtSIZ 1在体外具有SUMO E3连接酶活性，免疫印迹分析显示，蛋白质类小泛素化特征在siz 1植物中受损。AtSlZ 1-GFP定位于核灶。稳态转录丰度的Pi饥饿响应基因AtPT 2，AtPS 2和AtPS 3是温和的，但显然更大的siz 1幼苗比野生型，其中Pi是足够的。磷饥饿诱导这些基因的表达在siz 1和野生型幼苗相同的程度。然而，其他两个Pi饥饿响应基因，PIPPS 1和AtRNS 1，诱导更慢的siz 1幼苗由Pi限制。PHR 1是AtS 1 Z1类小泛素化的靶点，是AtS 1 Z1和AtRNS 1的MYB转录激活因子。这些结果表明，AtSlZ 1是一个SUMO E3连接酶和sumoylation是一个控制机制，既积极和消极的作用在不同的Pi缺乏反应。
Plants sense phosphate (Pi) deficiency and initiate signaling that controls adaptive responses necessary for Pi acquisition. Herein, evidence establishes that AtSIZ1 is a plant small ubiquitin-like modifier (SUMO) E3 ligase and is a focal controller of Pi starvation-dependent responses. T-DNA insertional mutated alleles of AtSIZ1 (At5g60410) cause Arabidopsis to exhibit exaggerated prototypical Pi starvation responses, including cessation of primary root growth, extensive lateral root and root hair development, increase in root/shoot mass ratio, and greater anthocyanin accumulation, even though intracellular Pi levels in siz1 plants were similar to wild type. AtSIZ1 has SUMO E3 ligase activity in vitro, and immunoblot analysis revealed that the protein sumoylation profile is impaired in siz1 plants. AtSlZ1-GFP was localized to nuclear foci. Steady-state transcript abundances of Pi starvation-responsive genes AtPT2, AtPS2, and AtPS3 were moderate but clearly greater in siz1 seedlings than in wild type, where Pi is sufficient. Pi starvation induced the expression of these genes to the same extent in siz1 and wild-type seedlings. However, two other Pi starvation-responsive genes, AtlPS1 and AtRNS1, are induced more slowly in siz1 seedlings by Pi limitation. PHR1, a MYB transcriptional activator of AtlPS1 and AtRNS1, is an AtSlZ1 sumoylation target. These results indicate that AtSlZ1 is a SUMO E3 ligase and that sumoylation is a control mechanism that acts both negatively and positively on different Pi deficiency responses.