AtHsp70-15-deficient Arabidopsis plants are characterized by reduced growth, a constitutive cytosolic protein response and enhanced resistance to TuMV
AtHsp70-15-deficient Arabidopsis plants are characterized by reduced growth, a constitutive cytosolic protein response and enhanced resistance to TuMV
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DOI：
10.1111/j.1365-313x.2011.04558.x
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发表时间：
2011-06-01
期刊：
影响因子：
7.2
通讯作者：
Sonnewald, Uwe
中科院分区：
文献类型：
--
作者：
Jungkunz, Isabel;Link, Katrin;Sonnewald, Uwe
拟南芥含有 18 个编码 Hsp70 的基因。该热休克蛋白超家族分为两个亚家族：DnaK 和 Hsp110/SSE。为了对 Hsp70 超家族成员进行功能表征，研究了胞浆 Hsp70 表达减少的功能丧失突变体。 AtHsp70-1 和 AtHsp70-2 是组成型表达的，代表环境条件下主要的胞质 Hsp70 同工型。与野生型对照相比，单突变体和双突变体的分析没有显示出任何差异。在酵母中，SSE 蛋白已被证明可充当核苷酸交换因子，对于 Hsp70 功能至关重要。为了测试 Hsp110/SSE 亚家族成员是否在植物中发挥重要功能，分析了该亚家族的两个成员 AtHsp70-14 和 AtHsp70-15。两个基因高度同源并且组成型表达。 AtHsp70-15 的缺乏而非 AtHsp70-14 的缺乏会导致严重的生长迟缓。 AtHsp70-15 缺陷型植物比野生型小，并且叶形略有不同。 AtHsp70-15 转基因植物中环境条件下的气孔关闭以及对 ABA 的反应受到损害，但 ABA 依赖性的发芽抑制并未受到影响。 AtHsp70-15 缺陷植物的热处理导致死亡率急剧增加，表明 AtHsp70-15 在拟南芥植物的正常生长和热反应中发挥着重要作用。 AtHsp70-15 缺陷的植物对萝卜花叶病毒的感染具有更强的耐受性。比较转录组分析表明，AtHsp70-15 缺陷植物表现出与胞质蛋白反应相似的组成型应激反应。基于这些结果，AtHsp70-15 可能是胞质蛋白正确折叠的关键因素，并且可能充当酵母的核苷酸交换因子。
Arabidopsis thaliana contains 18 genes encoding Hsp70s. This heat shock protein superfamily is divided into two sub-families: DnaK and Hsp110/SSE. In order to functionally characterize members of the Hsp70 superfamily, loss-of-function mutants with reduced cytosolic Hsp70 expression were studied. AtHsp70-1 and AtHsp70-2 are constitutively expressed and represent the major cytosolic Hsp70 isoforms under ambient conditions. Analysis of single and double mutants did not reveal any difference compared to wild-type controls. In yeast, SSE protein has been shown to act as a nucleotide exchange factor, essential for Hsp70 function. To test whether members of the Hsp110/SSE sub-family serve essential functions in plants, two members of the sub-family, AtHsp70-14 and AtHsp70-15, were analysed. Both genes are highly homologous and constitutively expressed. Deficiency of AtHsp70-15 but not of AtHsp70-14 led to severe growth retardation. AtHsp70-15-deficient plants were smaller than wild-type and exhibited a slightly different leaf shape. Stomatal closure under ambient conditions and in response to ABA was impaired in the AtHsp70-15 transgenic plants, but ABA-dependent inhibition of germination was not affected. Heat treatment of AtHsp70-15-deficient plants resulted in drastically increased mortality, indicating that AtHsp70-15 plays an essential role during normal growth and in the heat response of Arabidopsis plants. AtHsp70-15-deficient plants are more tolerant to infection by turnip mosaic virus. Comparative transcriptome analysis revealed that AtHsp70-15-deficient plants display a constitutive stress response similar to the cytosolic protein response. Based on these results, AtHsp70-15 is likely to be a key factor in proper folding of cytosolic proteins, and may function as nucleotide exchange factor as proposed for yeast.