Evolution of Bacterial Chaperonin 60 Paralogues and Moonlighting Activity
Evolution of Bacterial Chaperonin 60 Paralogues and Moonlighting Activity
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DOI：
10.1007/978-94-007-6787-4_7
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发表时间：
2013
影响因子：
5.6
通讯作者：
S. Mande;C. M. Kumar;Aditi Sharma
中科院分区：
文献类型：
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作者：
S. Mande;C. M. Kumar;Aditi Sharma
大约三分之二的基因组测序细菌编码一种伴侣蛋白 60 蛋白，另外三分之一编码 2 到 8 个伴侣蛋白 60 旁系同源物。一个令人惊讶的发现是，这些细菌蛋白在细菌内具有广泛且不断增长的附加功能，但主要是当 Cpn60 蛋白离开细胞并存在于细菌细胞壁或细菌外部环境中时。这些发现是在人们认识到细菌 Cpn60 蛋白可以呈现比原型十四聚体 E 更低的寡聚形式的同时发生的。大肠杆菌GroEL。 Cpn60 的较低寡聚形式可能更容易被分泌，并以与十四聚同系物和旁系同源物不同的方式与生物聚合物相互作用。 Cpn60兼职功能如何演变是一个需要解决的关键问题。为了解决这个问题，我们假设伴侣蛋白基因在进化过程中受到不同的选择性限制。基因复制以及随后的序列分歧导致了具有独特兼职活性的旁系同源 Cpn60 蛋白的进化。此外，这些功能变异可能是通过在功能重要的残基上引入化学上不同的取代来获得的。
Around two thirds of genome sequenced bacteria encode one chaperonin 60 protein with the other third encoding between two and eight chaperonin 60 paralogues. A surprising finding is that these bacterial proteins have a wide, and growing, range of additional functions both within the bacterium, but principally when the Cpn60 protein exits the cell and exists on the bacterial cell wall or in the bacterium’s external milieu. These findings have occurred at the same time that it has been realised that bacterial Cpn60 proteins can assume lower oligomeric forms than that of the prototypic tetradecamericE. coliGroEL. It is possible that lower oligomeric forms of Cpn60 may more readily be secreted and interact with biopolymers in a distinct manner to that of the tetradecameric homologues and paralogues. How the Cpn60 moonlighting functions evolved is a key question to be addressed. To address this question we postulate that the chaperonin genes have been subject to different selective constraints over evolutionary time. Gene duplication, followed by sequence divergence, resulted in the evolution of paralogous Cpn60 proteins that have distinct moonlighting activities. Moreover, these functional variations might be acquired by incorporating chemically dissimilar substitutions at functionally important residues.