A chaperonin from a thermophilic bacterium, Thermus thermophilus.
A chaperonin from a thermophilic bacterium, Thermus thermophilus.
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来自嗜热细菌（嗜热栖热菌）的伴侣蛋白。
DOI：
10.1098/rstb.1993.0029
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
H. Taguchi
中科院分区：
文献类型：
--
作者：
M. Yoshida;N. Ishii;E. Muneyuki;H. Taguchi
与大肠杆菌伴侣蛋白不同，来自嗜热细菌嗜热栖热菌（Thermus thermophilus）的伴侣蛋白（cpn）由GroEL（cpn 60）和GroES（cpn 10）的同源物组成，作为大复合物共纯化。在电子显微镜下，栖热菌的伴侣蛋白在侧视图中显示出子弹状的形状，而针对cpn 10的抗体仅结合在子弹的圆形侧面。我们的结论是，一个单一的cpn 60-七聚体环与两个条纹堆叠成两层和cpn 10寡聚体绑定到一侧的层。纯化的栖热菌伴侣蛋白含有内源性结合的ADP，与ATP孵育导致伴侣蛋白部分解离成cpn 60单体和cpn 10七聚体。在三个温度范围内，用盐酸胍稀释后，栖热菌伴侣蛋白对蛋白质重折叠的影响是不同的。在高于55摄氏度的高温下，天然蛋白质是稳定的，但它们的自发折叠失败，伴侣蛋白以ATP依赖的方式诱导生产性折叠。在中等温度（25-55 ℃）下，酶发生自发折叠，伴侣蛋白减慢折叠速率，而不改变生产性折叠的最终产率。在低于25摄氏度的低温下，自发折叠也会发生，即使在ATP存在的情况下，伴侣蛋白也会阻止折叠。当将相对热不稳定的蛋白质溶液在高温下孵育，然后在与ATP孵育后在其最佳温度下测量蛋白质的残余活性时，通过在溶液中包含栖热菌伴侣蛋白，导致蛋白质不可逆热变性的温度升高约10 ℃。（250字处删节）
Unlike Escherichia coli chaperonins, a chaperonin (cpn) from a thermophilic bacterium, Thermus thermophilus, consisting of homologues to GroEL (cpn 60) and GroES (cpn 10) is co-purified as a large complex. Thermus chaperonin shows a bullet-like shape in the side view seen by electron microscopy, and antibody against cpn 10 binds only to the round side of the bullet. We conclude that a single cpn 60-heptamer ring with two stripes stacks into two layers and a cpn 10 oligomer binds to one side of the layers. The purified Thermus chaperonin contains endogenously bound ADP, and incubation with ATP causes a partial dissociation of chaperonin into cpn 60 monomers and a cpn 10 heptamer. The effect of Thermus chaperonin on protein refolding upon dilution from guanidine HC1 is different at three temperature ranges. At high temperatures above 55 degrees C, where the native proteins are stable but their spontaneous foldings fail, the chaperonin induces productive folding in an ATP-dependent manner. At middle temperatures (25-55 degrees C) where spontaneous foldings of the enzymes occur, the chaperonin slows down the rate of folding without changing the final yield of productive folding. At lower temperatures below 25 degrees C where spontaneous foldings also occur, the chaperonin arrests the folding even in the presence of ATP. When a solution of relatively heat labile protein is incubated at high temperatures, and then residual activity of the protein is measured at its optimal temperature after incubation with ATP, the temperature that causes irreversible heat denaturation of the protein is elevated about 10 degrees C by inclusion of Thermus chaperonin in the solution.(ABSTRACT TRUNCATED AT 250 WORDS)