Analysis of a sugar response mutant of Arabidopsis identified a novel B3 domain protein that functions as an active transcriptional repressor
Analysis of a sugar response mutant of Arabidopsis identified a novel B3 domain protein that functions as an active transcriptional repressor
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DOI：
10.1104/pp.104.057752
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发表时间：
2005-06-01
期刊：
影响因子：
7.4
通讯作者：
Nakamura, K
中科院分区：
文献类型：
--
作者：
Tsukagoshi, H;Saijo, T;Nakamura, K
表达荧光素酶（LUC）的拟南芥（Arabidopsis thaliana）的隐性突变hsi2在源自甘薯（Ipomoea batatas）sporamin基因（Spo(min)::LUC）的短启动子的控制下导致在低糖和高糖条件下LUC表达增强，这不是由于脱落酸水平增加。 hsi2 突变体在编码具有 B3 DNA 结合结构域的蛋白质的基因中含有无义突变。 HSI2 和另外两种拟南芥蛋白似乎构成了一个新的 B3 结构域蛋白亚家族，与 ABI3、FUS3 和 LEC2 不同，后者是参与种子发育的转录激活因子。 HSI2 亚家族蛋白的 C 末端部分包含与 ERF 相关的两亲性抑制 (EAR) 基序相似的序列。 hsi2突变体中丢失的HSI2 C末端部分的缺失导致HSI2的核靶向减少。 HSI2 的空等位基因显示出比 hsi2 突变体更高的 Spo(min)::LUC 表达，而 HSI2 的过表达降低了 LUC 表达。原生质体中35S::HSI2与Spo(min)::LUC的瞬时共表达抑制了LUC活性的表达，EAR基序的缺失或突变显着降低了HSI2的抑制活性。这些结果表明HSI2和相关蛋白是B3结构域-EAR基序活性转录抑制因子。
A recessive mutation hsi2 of Arabidopsis ( Arabidopsis thaliana) expressing luciferase ( LUC) under control of a short promoter derived from a sweet potato ( Ipomoea batatas) sporamin gene ( Spo(min)::LUC) caused enhanced LUC expression under both low-and high- sugar conditions, which was not due to increased level of abscisic acid. The hsi2 mutant contained a nonsense mutation in a gene encoding a protein with B3 DNA- binding domain. HSI2 and two other Arabidopsis proteins appear to constitute a novel subfamily of B3 domain proteins distinct from ABI3, FUS3, and LEC2, which are transcription activators involved in seed development. The C- terminal part of HSI2 subfamily proteins contained a sequence similar to the ERF-associated amphiphilic repression ( EAR) motif. Deletion of the C- terminal portion of HSI2 lost in the hsi2 mutant caused reduced nuclear targeting of HSI2. Null allele of HSI2 showed even higher Spo(min)::LUC expression than the hsi2 mutant, whereas overexpression of HSI2 reduced the LUC expression. Transient coexpression of 35S::HSI2 with Spo(min)::LUC in protoplasts repressed the expression of LUC activity, and deletion or mutation of the EAR motif significantly reduced the repression activity of HSI2. These results indicate that HSI2 and related proteins are B3 domain- EAR motif active transcription repressors.