Heat-induced chaperone activity of serine/threonine protein phosphatase 5 enhances thermotolerance in Arabidopsis thaliana
Heat-induced chaperone activity of serine/threonine protein phosphatase 5 enhances thermotolerance in Arabidopsis thaliana
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DOI：
10.1111/j.1469-8137.2011.03734.x
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发表时间：
2011-01-01
期刊：
影响因子：
9.4
通讯作者：
Lee, Sang Yeol
中科院分区：
文献类型：
--
作者：
Park, Jin Ho;Lee, Sun Yong;Lee, Sang Yeol
本研究报道了拟南芥丝氨酸/苏氨酸磷酸酶5(AtPP5)在抗热胁迫中的关键作用。从经过热处理的拟南芥悬浮细胞中分离到一种高分子量的AtPP5。AtPP5具有多种功能，可作为蛋白磷酸酶、折叠酶伴侣和保持酶伴侣。这种多功能蛋白的酶活性与其低聚状态密切相关，从低聚蛋白到HMW复合体。AtPP5的磷酸酶和折叠酶伴侣功能主要与低分子量形式有关，而HMW形式则表现出保持酶伴侣活性。转基因AtPP5的过表达增强了野生型拟南芥的抗热激能力，而T-DNA插入敲除突变体在获得耐热性方面存在缺陷。一个重组磷酸酶突变体(H290N)表现出明显的保持酶伴侣活性增强。此外，在过量表达H290N的转基因植物中观察到耐热性增强，这表明AtPP5的保持酶伴侣活性是导致AtPP5介导的耐热性的主要原因。
This study reports that Arabidopsis thaliana protein serine/threonine phosphatase 5 (AtPP5) plays a pivotal role in heat stress resistance. A high-molecular-weight (HMW) form of AtPP5 was isolated from heat-treated A. thaliana suspension cells. AtPP5 performs multiple functions, acting as a protein phosphatase, foldase chaperone, and holdase chaperone. The enzymatic activities of this versatile protein are closely associated with its oligomeric status, ranging from low oligomeric protein species to HMW complexes.The phosphatase and foldase chaperone functions of AtPP5 are associated primarily with the low-molecular-weight (LMW) form, whereas the HMW form exhibits holdase chaperone activity. Transgenic over-expression of AtPP5 conferred enhanced heat shock resistance to wild-type A. thaliana and a T-DNA insertion knock-out mutant was defective in acquired thermotolerance. A recombinant phosphatase mutant (H290N) showed markedly increased holdase chaperone activity.In addition, enhanced thermotolerance was observed in transgenic plants over-expressing H290N, which suggests that the holdase chaperone activity of AtPP5 is primarily responsible for AtPP5-mediated thermotolerance.Collectively, the results from this study provide the first evidence that AtPP5 performs multiple enzymatic activities that are mediated by conformational changes induced by heat-shock stress.