Arabidopsis HsfB1 and HsfB2b Act as Repressors of the Expression of Heat-Inducible Hsfs But Positively Regulate the Acquired Thermotolerance
Arabidopsis HsfB1 and HsfB2b Act as Repressors of the Expression of Heat-Inducible Hsfs But Positively Regulate the Acquired Thermotolerance
复制标题
DOI：
10.1104/pp.111.179036
复制
发表时间：
2011-11-01
期刊：
影响因子：
7.4
通讯作者：
Ohme-Takagi, Masaru
中科院分区：
文献类型：
--
作者：
Ikeda, Miho;Mitsuda, Nobutaka;Ohme-Takagi, Masaru
许多真核生物具有一到三种热激因子（Hsfs），但植物具有超过20种Hsfs，被指定为A、B和C类。A类Hsf是转录激活因子，但单个Hsf的作用细节尚未完全表征。我们在这里表明，拟南芥（拟南芥）HsfB1和HsfB2 B，类B的成员，是转录抑制因子和负调控热诱导型Hsfs（HsfA2，HsfA7 a，HsfB1，和HsfB2 B）和几个热休克蛋白基因的表达。在hsfb1 hsfb2b双突变体植物中，大量热诱导基因的表达在非热条件（23 ℃）下增强，并且植物在42 ℃下表现出比野生型略高的耐热性，类似于Pro35S：HsfA2植物。此外，在延长的热应激条件下，热诱导型Hsf基因的表达始终高于hsfb1 hsfb2b在野生型。这些数据表明，HsfB1和HsfB2b在非热应激条件下和衰减期抑制一般热休克反应。另一方面，HsfB1和HsfB2b似乎是必需的热应激诱导的热休克蛋白基因的表达在热应激条件下，这是必要的获得热耐受性。我们表明，热胁迫反应是精细调节激活和抑制活动的拟南芥中的Hsfs。
Many eukaryotes have from one to three heat shock factors (Hsfs), but plants have more than 20 Hsfs, designated class A, B, and C. Class A Hsfs are activators of transcription, but details of the roles of individual Hsfs have not been fully characterized. We show here that Arabidopsis (Arabidopsis thaliana) HsfB1 and HsfB2b, members of class B, are transcriptional repressors and negatively regulate the expression of heat-inducible Hsfs (HsfA2, HsfA7a, HsfB1, and HsfB2b) and several heat shock protein genes. In hsfb1 hsfb2b double mutant plants, the expression of a large number of heat-inducible genes was enhanced in the non-heat condition (23 degrees C) and the plants exhibited slightly higher heat tolerance at 42 degrees C than the wild type, similar to Pro35S:HsfA2 plants. In addition, under extended heat stress conditions, expression of the heat-inducible Hsf genes remained consistently higher in hsfb1 hsfb2b than in the wild type. These data indicate that HsfB1 and HsfB2b suppress the general heat shock response under non-heat-stress conditions and in the attenuating period. On the other hand, HsfB1 and HsfB2b appear to be necessary for the expression of heat stress-inducible heat shock protein genes under heat stress conditions, which is necessary for acquired thermotolerance. We show that the heat stress response is finely regulated by activation and repression activities of Hsfs in Arabidopsis.