Contribution of the C-terminal region to the thermostability of the archaeal group II chaperonin from Thermococcus sp. strain KS-1
Contribution of the C-terminal region to the thermostability of the archaeal group II chaperonin from Thermococcus sp. strain KS-1
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DOI：
10.1007/s00792-006-0519-y
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发表时间：
2006-05
期刊：
影响因子：
2.9
通讯作者：
Takao Yoshida;Taro Kanzaki;R. Iizuka;Toshihiro Komada;T. Zako;R. Suzuki;T. Maruyama;M. Yohda
中科院分区：
文献类型：
--
作者：
Takao Yoshida;Taro Kanzaki;R. Iizuka;Toshihiro Komada;T. Zako;R. Suzuki;T. Maruyama;M. Yohda
伴侣蛋白是一种双环状的寡聚蛋白复合物，其捕获处于折叠中间状态的蛋白质并以ATP依赖的方式帮助其折叠。超嗜热古菌Thermococcussp.菌株KS-1是II类伴侣蛋白，由两个不同的亚基α和β组成。虽然这些亚基在序列上高度同源，但β亚基的同源寡聚体比α亚基的同源寡聚体更耐热。为了确定该地区负责这种差异的热稳定性，我们构建了结构域交换突变体。含有β亚基赤道区的突变体比含有α亚基赤道区的突变体更耐热解离。C端22个残基被α亚基取代的β亚基突变体的热稳定性降低到与α亚基同源寡聚体相当的水平。这些结果表明，α-亚基和β-亚基之间的热稳定性差异主要来源于赤道区的C-末端残基，只有在赤道区的C-末端残基上，它们才表现出明显的序列差异。
Chaperonin is a double ring-shaped oligomeric protein complex, which captures a protein in the folding intermediate state and assists its folding in an ATP-dependent manner. The chaperonin from a hyperthermophilic archaeum,Thermococcussp. strain KS-1, is a group II chaperonin and is composed of two distinct subunits, α and β. Although these subunits are highly homologous in sequence, the homo-oligomer of the β-subunit is more thermostable than that of the α-subunit. To identify the region responsible for this difference in thermostability, we constructed domain-exchange mutants. The mutants containing the equatorial domain of the β-subunit were more resistant to thermal dissociation than the mutants with that of the α-subunit. Thermostability of a β-subunit mutant whoseC-terminal 22 residues were replaced with those of the α-subunit decreased to the comparable level of that of the α-subunit homo-oligomer. These results indicate that the difference in thermostability between α- and β-subunits mainly originates in theC-terminal residues in the equatorial domain, only where they exhibit substantial sequence difference.