Download MendeleyStructure, flexibility, and mechanism of the Bacillus stearothermophilus RecU Holliday junction resolvase.
Kelly, S.J., Li, J., Setlow, P., Jedrzejas, M.J.(2007) Proteins 68: 961-971
- PubMed: 17557334
- DOI: https://doi.org/10.1002/prot.21418
- Primary Citation of Related Structures:
2FCO - PubMed Abstract:
Here we report a high resolution structure of RecU-Holliday junction resolvase from Bacillus stearothermophilus. The functional unit of RecU is a homodimer that contains a "mushroom" like structure with a rigid cap and two highly flexible loops extending outwards. These loops appear to be highly flexible/dynamic, and presumably are directly involved in DNA binding and holding it for catalysis. Structural modifications of both the protein and DNA upon their interaction are essential for catalysis. An Mg2+ ion is present in each of the two active sites in this homodimeric enzyme, and two water molecules are coordinated with each Mg2+ ion. Our data are consistent with one of these water molecules acting as a nucleophile and the other as a general acid. The identities of the general base and general acid involved in catalysis and the Lewis acid that stabilizes the pentacovalent transition state phosphate ion are proposed. A model for the RecU-Holliday junction DNA complex is also proposed and discussed in the context of DNA binding and cleavage.
Organizational Affiliation:
Children's Hospital Oakland Research Institute, Oakland, CA 94609, USA.
