| Autor: |
Shigenori Kanaya, Nujarin Jongruja, Dong-Ju You, Eiko Kanaya, Clement Angkawidjaja, Yuichi Koga |
| Rok vydání: |
2012 |
| Předmět: |
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| Zdroj: |
FEBS Journal. 279:2737-2753 |
| ISSN: |
1742-464X |
| DOI: |
10.1111/j.1742-4658.2012.08657.x |
| Popis: |
The crystal structure of ribonuclease H3 from Aquifex aeolicus (Aae-RNase H3) was determined at 2.0 A resolution. Aae-RNase H3 consists of an N-terminal TATA box-binding protein (TBP)-like domain (N-domain) and a C-terminal RNase H domain (C-domain). The structure of the C-domain highly resembles that of Bacillus stearothermophilus RNase H3 (Bst-RNase H3), except that it contains three disulfide bonds, and the fourth conserved glutamate residue of the Asp-Glu-Asp-Glu active site motif (Glu198) is located far from the active site. These disulfide bonds were shown to contribute to hyper-stabilization of the protein. Non-conserved Glu194 was identified as the fourth active site residue. The structure of the N-domain without the C-domain also highly resembles that of Bst-RNase H3. However, the arrangement of the N-domain relative to the C-domain greatly varies for these proteins because of the difference in the linker size between the domains. The linker of Bst-RNase H3 is relatively long and flexible, while that of Aae-RNase H3 is short and assumes a helix formation. Biochemical characterizations of Aae-RNase H3 and its derivatives without the N- or C-domain or with a mutation in the N-domain indicate that the N-domain of Aae-RNase H3 is important for substrate binding, and uses the flat surface of the β-sheet for substrate binding. However, this surface is located far from the active site and on the opposite side to the active site. We propose that the N-domain of Aae-RNase H3 is required for initial contact with the substrate. The resulting complex may be rearranged such that only the C-domain forms a complex with the substrate. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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