Identification and characterization of the Escherichia coli stress protein UP12, a putative in vivo substrate of GroEL
Identification and characterization of the Escherichia coli stress protein UP12, a putative in vivo substrate of GroEL
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DOI：
10.1046/j.1432-1033.2002.02978.x
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发表时间：
2002-06-01
期刊：
影响因子：
--
通讯作者：
Bibi, E
中科院分区：
文献类型：
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作者：
Bochkareva, ES;Girshovich, AS;Bibi, E
许多蛋白质组在细胞对各种压力的反应中起着重要作用。大肠杆菌的分子伴侣GroEL代表了这样一个高度保守的应激蛋白家族。我们观察到从固定培养中分离出的GroEL复合物含有多种多肽，这些多肽可以通过GroES和/或ATP从伴侣蛋白中释放出来，并鉴定出两种多肽，即蛋白质gay和UP12。尽管之前已经分离出了gally，作为GroEL的体内底物，但在与GroEL复合物中分离出UP12是很有趣的，因为基于序列相似性，这表明UP12也可能是一种功能性应激蛋白。UP12属于通用应激蛋白家族（UspA家族），其中UspA本身和另外三个类似物已经被表征。在这里，我们发现UP12在各种生长抑制条件下和热休克诱导下积累。此外，与野生型细胞不同，UP12缺失突变体从后期稳定生长条件中恢复缓慢，并且对有毒物质羰基氰化物间氯苯腙（CCCP）具有明显的敏感性。最后，共免疫沉淀实验证实了UP12与GroEL相互作用的初步观察。因此，我们认为UP12可能是一种通用的应激蛋白，它与GroEL的相互作用可能保证了UP12的正常折叠状态。
Many groups of proteins play important roles in the cell's response to various stresses. The molecular chaperone GroEL of Escherichia coli represents one such highly conserved family of stress proteins. We have observed that isolated GroEL complexes from stationary cultures contain various polypeptides that can be released from the chaperonin by GroES and/or ATP, and identified two such polypeptides as the proteins GatY and UP12. Whereas GatY had been isolated previously, as an in vivo substrate of GroEL, the isolation of UP12 in a complex with GroEL was intriguing, because based on sequence similarity it was suggested that UP12 might also be a functional stress protein. UP12 belongs to a family of universal stress proteins (UspA family), of which UspA itself, and three additional paralogues, have been characterized previously. Here we show that UP12 accumulates under various growth inhibitory conditions and induced by heat shock. Furthermore, unlike wild-type cells, a UP12 deletion mutant recovers slowly from late stationary growth conditions, and has a marked sensitivity to the toxic agent carbonyl cyanide m-chlorophenyl hydrazone (CCCP). Finally, coimmunoprecipitation experiments confirmed the initial observation that UP12 interacts with GroEL. Therefore, we suggest that UP12 may function as a universal stress protein, interaction of which with GroEL possibly ensures its proper folding state.