Replacement of GroEL in Escherichia coli by the Group II Chaperonin from the Archaeon Methanococcus maripaludis.
Replacement of GroEL in Escherichia coli by the Group II Chaperonin from the Archaeon Methanococcus maripaludis.
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DOI：
10.1128/jb.00317-16
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发表时间：
2016-10-01
影响因子：
3.2
通讯作者：
Lund PA
中科院分区：
文献类型：
--
作者：
Shah R;Large AT;Ursinus A;Lin B;Gowrinathan P;Martin J;Lund PA
伴侣蛋白是许多蛋白质正确折叠所必需的。它们存在于两个系统发育组中：组I，发现于细菌和真核细胞器中，组II，发现于古细菌和真核细胞质中。这两组虽然同源，但在结构和机制上有很大差异。已经提出II组伴侣蛋白的进化在使真核生物进化所需的蛋白质组的扩展中是至关重要的。在一个古细菌物种，表达这两组伴侣蛋白，客户端的选择是由结构和生化特性，而不是系统发育起源。因此，预测II组伴侣蛋白在替代I组伴侣蛋白方面将是差的。我们已经测试了这一假设，并在这里报告，第二组伴侣从甲烷球菌maripaludis（Mm-cpn）可以部分功能取代GroEL，第一组伴侣的大肠杆菌。此外，我们确定并表征了Mm-cpn中的两个单点突变，它们具有增强的替代GroEL功能的能力，包括允许E.在删除groEL基因后的大肠杆菌生长。野生型和突变型Mm-cpn蛋白的生化特性的报告。这些数据表明，这两个群体并不像人们所认为的那样功能多样，并为II组伴侣蛋白的遗传解剖提供了一个新的平台。重要性这两个系统发育组的基本和普遍存在的伴侣蛋白分歧约37亿年前。它们具有相似的结构，具有两个由多个亚基组成的环，它们的主要作用是帮助蛋白质折叠。然而，它们在结构细节、辅因子要求和反应循环方面有所不同。尽管如此，我们在这里表明，第二组伴侣蛋白从产甲烷古菌可以部分取代的基本组I伴侣蛋白GroEL在大肠杆菌。大肠杆菌，我们可以很容易地分离出突变形式的这种伴侣蛋白进一步改善功能。这是第一次证明，这两个群体，尽管很长一段时间以来，他们的分歧，仍然重叠显着的功能特性。
Chaperonins are required for correct folding of many proteins. They exist in two phylogenetic groups: group I, found in bacteria and eukaryotic organelles, and group II, found in archaea and eukaryotic cytoplasm. The two groups, while homologous, differ significantly in structure and mechanism. The evolution of group II chaperonins has been proposed to have been crucial in enabling the expansion of the proteome required for eukaryotic evolution. In an archaeal species that expresses both groups of chaperonins, client selection is determined by structural and biochemical properties rather than phylogenetic origin. It is thus predicted that group II chaperonins will be poor at replacing group I chaperonins. We have tested this hypothesis and report here that the group II chaperonin from Methanococcus maripaludis (Mm-cpn) can partially functionally replace GroEL, the group I chaperonin of Escherichia coli. Furthermore, we identify and characterize two single point mutations in Mm-cpn that have an enhanced ability to replace GroEL function, including one that allows E. coli growth after deletion of the groEL gene. The biochemical properties of the wild-type and mutant Mm-cpn proteins are reported. These data show that the two groups are not as functionally diverse as has been thought and provide a novel platform for genetic dissection of group II chaperonins. IMPORTANCE The two phylogenetic groups of the essential and ubiquitous chaperonins diverged approximately 3.7 billion years ago. They have similar structures, with two rings of multiple subunits, and their major role is to assist protein folding. However, they differ with regard to the details of their structure, their cofactor requirements, and their reaction cycles. Despite this, we show here that a group II chaperonin from a methanogenic archaeon can partially substitute for the essential group I chaperonin GroEL in E. coli and that we can easily isolate mutant forms of this chaperonin with further improved functionality. This is the first demonstration that these two groups, despite the long time since they diverged, still overlap significantly in their functional properties.