量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum Science and Technology.
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Thioredoxin (TRX) is an important antioxidant to resist the oxidative stress. In this study, the structure of TRX from an extreme halophilic archaea Halobacterium NRC-1 (HsTRX-A, UniProtKB: O46709) having the highest acidic residue content [(D+E)/(K+R+H)=9.0] in the known TRXs was investigated to elucidate its haloadaptation mechanism. X-ray crystallographic analysis revealed that the structure of HsTRX-A was similar to those of the extant archaeal and non-halophilic TRXs (RMSDs for Cα atoms < 2.3 Å) and the resurrected Precambrian TRXs (RMSDs for Cα atoms < 1.5 Å) [1]. Although the structure of HsTRX-A was almost conserved throughout evolution, HsTRX-A has unique properties; e.g. the high density of negative charges (0.0035 Å-2) and the long hydrophilic N-terminal region (R1-D34), both of which improve the solubility of protein. Moreover, the water network formed by four water molecules was found near the active site residues (C47 and C50), which may assist the proton transfer at the active site residues under high salt environment. These observations will be helpful to understand the haloadaptation mechanism and molecular evolution of HsTRX-A. [1] Ingles-Prieto, A. et al. (2013) Structure, 21, 1690.
Haloadaptation mechanism and evolutional characteristics of thioredoxin from Halobacterium NRC-1
