嗜热栖热菌的小分子热休克蛋白
Small heat shock protein of Methanococcus jannaschii, a hyperthermophile.
作者信息
Kim R, Kim K K, Yokota H, Kim S H
机构信息
Physical Biosciences Division of Lawrence Berkeley, National Laboratory and Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720-5230, USA.
出版信息
Proc Natl Acad Sci U S A. 1998 Aug 4;95(16):9129-33. doi: 10.1073/pnas.95.16.9129.
Small heat shock proteins (sHSPs) belong to a family of 12- to 43-kDa proteins that are ubiquitous and are conserved in amino acid sequence among all organisms. A sHSP homologue of Methanococcus jannaschii, a hyperthermophilic Archaeon, forms a homogeneous multimer comprised of 24 monomers with a molecular mass of 400 kDa in contrast to other sHSPs that show heterogeneous oligomeric complexes. Electron microscopy analysis revealed a spherically shaped oligomeric structure approximately 15-20 nm in diameter. The protein confers thermal protection of other proteins in vitro as found in other sHSPs. Escherichia coli cell extracts containing the protein were protected from heat-denatured precipitation when heated up to 100 degreesC, whereas extracts from cells not expressing the protein were heat-sensitive at 60 degreesC. Similar results were obtained when purified sHSP protein was added to an E. coli cell lysate. The protein also prevented the aggregation of two purified proteins: single-chain monellin (SCM) at 80 degreesC and citrate synthase at 40 degreesC.
小热休克蛋白（sHSPs）属于一类分子量为12至43 kDa的蛋白质家族，这类蛋白质普遍存在，且在所有生物体中的氨基酸序列都具有保守性。嗜热古菌詹氏甲烷球菌的一种sHSP同源物形成了一种由24个单体组成的均匀多聚体，分子量为400 kDa，这与其他显示出异质寡聚复合物的sHSPs不同。电子显微镜分析揭示了一种直径约为15 - 20 nm的球形寡聚结构。与其他sHSPs一样，该蛋白质在体外赋予其他蛋白质热保护作用。含有该蛋白质的大肠杆菌细胞提取物在加热至100℃时可免受热变性沉淀的影响，而未表达该蛋白质的细胞提取物在60℃时对热敏感。当将纯化的sHSP蛋白添加到大肠杆菌细胞裂解物中时，也获得了类似的结果。该蛋白质还能防止两种纯化蛋白质的聚集：80℃下的单链莫内林（SCM）和40℃下的柠檬酸合酶。
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