What is it about?
We found that the CutA1 protein from Pyrococcus horikoshii (PhCutA1), has an extremely high denaturation tem- perature (Td) of nearly 150 °C, which exceeds the highest record determined by DSC by about 30 °C. To elucidate the mechanism of the ultra-high stability of PhCutA1, we analyzed the crystal structures of CutA1 proteins from three different sources, P. hor- ikoshii, Thermus thermophilus, and Escherichia coli, with differ- ent growth temperatures (98, 75, and 37 °C). This analysis revealed that the remarkably increased number of ion pairs in the monomeric structure contributes to the stabilization of the trimeric structure and plays an important role in enhancing the Td, up to 150 °C, for PhCutA1.
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Why is it important?
Fortunately, in the case of CutA1, the X-ray crystal struc- tures from three sources with different growth temperatures (98, 75, and 37 °C), from P. horikoshii (hyperthermophile), Thermus thermophilus (extreme thermophile), and Escherichia coli (mesophile), have been solved. The CutA1 protein was originally identified in the cutA gene locus of E. coli, which is involved in divalent metal tolerance [16]. The specific func- tion of CutA1 in E. coli is still unknown. The CutA1 protein is widely found in bacteria, plants, and animal, including hu- mans. The mammalian CutA1 may play a role in the anchor- ing of the enzyme acetylcholinesterase in neuronal cell membranes [17]. In this paper, we analyzed the mechanism underlying the hyper-thermostability of PhCutA1, using the three structures.
Perspectives
The thermo-stabilization mechanism of PhCutA1, which is stable up to 150 °C, involves the crucial contribution of ion pairs to maintain the protein conforma- tion at extremely high temperatures. This exclusive role of ion pairs in the extremely high thermostability could be con- firmed as several extremely stable proteins from hypertherm- ophiles, with Tds up to or higher than 150 °C, are found in the near future.
Dr Bagautdin Bagautdinov
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This page is a summary of: Hyper-thermostability of CutA1 protein, with a denaturation temperature of nearly 150 °C, FEBS Letters, July 2006, Wiley,
DOI: 10.1016/j.febslet.2006.06.084.
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