Publication: Structural basis for salt-dependent folding of ribonuclease H1 from halophilic archaeon Halobacterium sp. NRC-1
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Issued Date
2014-01-01
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ISSN
10958657
10478477
10478477
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2-s2.0-84906101126
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Mahidol University
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SCOPUS
Bibliographic Citation
Journal of Structural Biology. Vol.187, No.2 (2014), 119-128
Suggested Citation
Dong Ju You, Nujarin Jongruja, Elias Tannous, Clement Angkawidjaja, Yuichi Koga, Shigenori Kanaya Structural basis for salt-dependent folding of ribonuclease H1 from halophilic archaeon Halobacterium sp. NRC-1. Journal of Structural Biology. Vol.187, No.2 (2014), 119-128. doi:10.1016/j.jsb.2014.06.005 Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/33429
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Title
Structural basis for salt-dependent folding of ribonuclease H1 from halophilic archaeon Halobacterium sp. NRC-1
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Abstract
RNase H1 from extreme halophilic archaeon Halobacterium sp. NRC-1 (Halo-RNase H1) requires ≥2M NaCl, ≥10mM MnCl2, or ≥300mM MgCl2for folding. To understand the structural basis for this salt-dependent folding of Halo-RNase H1, the crystal structure of Halo-RNase H1was determined in the presence of 10mM MnCl2. The structure of Halo-RNase H1 highly resembles those of metagenome-derived LC11-RNase H1 and Sulfolobus tokodaii RNase H1 (Sto-RNase H1), except that it contains two Mn2+ions at the active site and has three bi-aspartate sites on its surface. To examine whether negative charge repulsion at these sites are responsible for low-salt denaturation of Halo-RNase H1, a series of the mutant proteins of Halo-RNase H1 at these sites were constructed. The far-UV CD spectra of these mutant proteins measured in the presence of various concentrations of NaCl suggest that these mutant proteins exist in an equilibrium between a partially folded state and a folded state. However, the fraction of the protein in a folded state is nearly 0% for the active site mutant, 40% for the bi-aspartate site mutant, and 70% for the mutant at both sites in the absence of salt. The active site mutant requires relatively low concentration (~0.5M) of salt for folding. These results suggest that suppression of negative charge repulsion at both active and bi-aspartate sites by salt is necessary to yield a folded protein. © 2014 Elsevier Inc.