Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 500 Caobao Road, Shanghai, China.
Biotechnol Lett. 2011 Aug;33(8):1649-55. doi: 10.1007/s10529-011-0615-7. Epub 2011 Apr 8.
Compared to the group I chaperonins, such as Escherichia coli GroEL, which facilitate protein folding, many aspects of the functional mechanism of archaeal group II chaperonins are unclear. Sequence homology between the chaperonin from Pyrococcus furiosus (PfCPN) and other group II chaperonins, together with the homo-oligomeric nature of PfCPN, suggest that PfCPN may serve as a model to clarify the role of the homologous position Gly-345 in the chaperonin-mediated protein folding. Here, we show that the purified chaperonin mutant in which the conserved residue Gly-345 is replaced by Asp (G345D) displays only about 25% ATP/ADP hydrolysis activities of the wild-type in the presence of Co(2+) and has a reduced capacity to promote folding of denatured malate dehydrogenase in vitro. This may be a reflection that Gly-345 plays an essential role in conformational change and protein refolding by archaeal group II chaperonins.
与大肠杆菌 GroEL 等促进蛋白质折叠的 I 类分子伴侣相比，许多古菌 II 类分子伴侣的功能机制仍不清楚。火球菌（Pyrococcus furiosus）分子伴侣（PfCPN）与其他 II 类分子伴侣的序列同源性，以及 PfCPN 的同型寡聚性质，表明 PfCPN 可能是阐明同源位置 Gly-345 在伴侣介导的蛋白质折叠中的作用的模型。在这里，我们表明，纯化的突变体分子伴侣中，保守残基 Gly-345 被 Asp 取代（G345D），在 Co(2+)存在下，其 ATP/ADP 水解活性仅为野生型的约 25%，并且体外促进变性苹果酸脱氢酶折叠的能力降低。这可能反映了 Gly-345 在古菌 II 类分子伴侣的构象变化和蛋白质重折叠中发挥着重要作用。
