Biochemical and biophysical characterization of small heat shock proteins from sugarcane. Involvement of a specific region located at the N-terminus with substrate specificity.
Biochemical and biophysical characterization of small heat shock proteins from sugarcane. Involvement of a specific region located at the N-terminus with substrate specificity.
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DOI：
10.1016/j.biocel.2007.01.014
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发表时间：
2007
期刊：
影响因子：
--
通讯作者：
Ana O. Tiroli;C. Ramos
中科院分区：
文献类型：
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作者：
Ana O. Tiroli;C. Ramos
当细胞处于温度升高时，会合成热休克蛋白(HSP)来帮助抵抗热应激。小分子热休克蛋白在植物中种类繁多，含量丰富，具有阻止蛋白质不可逆聚集的主要功能。植物中小分子热休克蛋白的多样性令人感兴趣，其伴侣活性的表征对于了解植物对热胁迫的耐受性很重要。先前的研究表明，小分子热休克蛋白主要以I类(胞质)为代表，相当于所有甘蔗表达的测序标签中约5%属于分子伴侣类。本文介绍了两个甘蔗小分子热休克蛋白的生化和生物物理性质，分别命名为SsHsp17.2和SsHsp17.9，其单体分子质量分别为17.2和17.9 kDa。重组蛋白具有约75%的同源性和相似的结构特征。然而，它们的稳定性和伴侣活性并不相同：SsHsp17.9对柠檬酸合成酶和苹果酸脱氢酶的保护作用更强，而SsHsp17.2对荧光素酶的保护作用更强。这两个蛋白质之间只有一个区域位于N-末端，同源性很低。在此基础上，结合前人的工作，我们认为小分子热休克蛋白中涉及底物专一性的多个位点，主要位于N端，我们认为该特定区域就是其中之一。此外，这也是甘蔗小分子热休克蛋白伴侣活性的首次报道。
When cells are submitted to an increase in temperature, heat shock proteins (Hsp) are synthesized to help heat stress resistance. Small Hsps, which are diverse and abundant in plants, have the major function of preventing irreversible protein aggregation. The diversity of small Hsps in plants is intriguing and characterization of their chaperone activity is important to understand plant tolerance to heat stress. A previous study showed that small Hsps, mainly represented by class I (cytosolic), correspond to about 5% of all sugarcane Expressed Sequencing Tags belonging to the molecular chaperone category. Here, we present biochemical and biophysical characterization of two sugarcane small Hsps from class I, which were named SsHsp17.2 and SsHsp17.9 according to their monomer molecular mass of 17.2 and 17.9kDa, respectively. The recombinant proteins have identity of about 75% to each other and similar structural characteristics. However, their stability and their chaperone activity were not equivalent: SsHsp17.9 was more efficient in protecting citrate synthase and malate dehydrogenase from aggregation whereas SsHsp17.2 was more efficient in protecting luciferase from aggregation. There is only one region, which is located at the N-terminus, of low homology between these two proteins. Based on that and on previous works pointing to multiple sites, mainly at the N-terminus, involved with substrate specificity in small Hsps, we suggest that this specific region is one of these sites. In addition, this is the first report on the chaperone activity of sugarcane small Hsps.