Iizuka R, Yoshida T, Maruyama T, Shomura Y, Miki K, Yohda M
Department of Biotechnology and Life Science, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo, 184-8588, Japan
Biochem Biophys Res Commun. 2001 Dec 21;289(5):1118-24. doi: 10.1006/bbrc.2001.6139.
In the previous study, we have found that G65C and I125T double mutant of alpha chaperonin homo-oligomer from a hyperthermophilic archaeum, Thermococcus sp. strain KS-1, lacks ATP-dependent protein refolding activity despite showing ATPase activity and the ability to bind the denatured proteins. In this study, we have characterized several mutant Thermococcus chaperonin homo-oligomers with the amino acid substitutions of Gly-65 or Ile-125. The results showed that amino acid residue at 65th position should be a small amino acid such as glycine or alanine for the ATP-dependent refolding activity. The alpha chaperonin homo-oligomers with amino acid substitution of Gly-65 by amino acids whose side chains are larger than the methyl group did not have ATP-dependent protein refolding activity, but exhibited an increase of the binding affinity for unfolded proteins in the presence of ATP or AMP-PNP. (c)2001 Elsevier Science.
在之前的研究中，我们发现来自嗜热古菌嗜热栖热菌（Thermococcus sp. strain KS-1）的α伴侣蛋白同型寡聚体的G65C和I125T双突变体，尽管具有ATP酶活性以及结合变性蛋白的能力，但缺乏ATP依赖的蛋白重折叠活性。在本研究中，我们对几种具有Gly-65或Ile-125氨基酸取代的嗜热栖热菌伴侣蛋白同型寡聚体突变体进行了表征。结果表明，第65位的氨基酸残基应为甘氨酸或丙氨酸等小氨基酸，才能具有ATP依赖的重折叠活性。侧链大于甲基的氨基酸取代Gly-65的α伴侣蛋白同型寡聚体不具有ATP依赖的蛋白重折叠活性，但在ATP或AMP-PNP存在的情况下，对未折叠蛋白的结合亲和力增加。(c)2001爱思唯尔科学出版社。
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