The chemical chaperone proline relieves the thermosensitivity of a dnaK deletion mutant at 42°C
The chemical chaperone proline relieves the thermosensitivity of a dnaK deletion mutant at 42°C
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DOI：
10.1128/jb.186.23.8149-8152.2004
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发表时间：
2004-12-01
影响因子：
3.2
通讯作者：
Richarme, G
中科院分区：
文献类型：
--
作者：
Chattopadhyay, MK;Kern, R;Richarme, G
由于与其他渗透调节物质一样，Pro可以作为蛋白质的稳定剂，因此我们在体外和体内研究了Pro的热保护性。在体内，大肠杆菌中升高的脯氨酸库(通过改变Pro生物合成途径的第一个酶-谷氨酸激酶的反馈抑制而获得)在42℃恢复了dNAK缺陷突变体的活力，这表明Pro可以作为大肠杆菌细胞的热保护剂。此外，用双向凝胶电泳法对dNAK缺陷菌株在42℃时的聚集蛋白进行分析，结果表明高的脯氨酸库减少了dNAK缺陷菌株的蛋白质聚集缺陷。在体外，与其他“化学伴侣”和DNAK伴侣一样，Pro保护柠檬酸合成酶免受热变性，并在尿素变性后刺激柠檬酸合成酶的复性。这些结果表明，蛋白质聚集缺陷可以通过氨基酸生物合成途径中的单个突变来补偿，而普遍存在的化学伴侣可以补偿参与蛋白质折叠和聚集的主要伴侣之一的缺陷。
Since, like other osmolytes, proline can act as a protein stabilizer, we investigated the thermoprotectant properties of proline in vitro and in vivo. In vivo, elevated proline pools in Escherichia coli (obtained by altering the feedback inhibition by proline of gamma-glutamylkinase, the first enzyme of the proline biosynthesis pathway) restore the viability of a dnaK-deficient mutant at 42degreesC, suggesting that proline can act as a thermoprotectant for E. coli cells. Furthermore, analysis of aggregated proteins in the dnaK-deficient strain at 42degreesC by two-dimensional gel electrophoresis shows that high proline pools reduce the protein aggregation defect of the dnaK-deficient strain. In vitro, like other "chemical chaperones," and like the DnaK chaperone, proline protects citrate synthase against thermodenaturation and stimulates citrate synthase renaturation after urea denaturation. These results show that a protein aggregation defect can be compensated for by a single mutation in an amino acid biosynthetic pathway and that an ubiquitously producible chemical chaperone can compensate for a defect in one of the major chaperones involved in protein folding and aggregation.