Download MendeleyAlternative native flap conformation revealed by 2.3 A resolution structure of SIV proteinase.
Wilderspin, A.F., Sugrue, R.J.(1994) J Mol Biol 239: 97-103
- PubMed: 8196050
- DOI: https://doi.org/10.1006/jmbi.1994.1353
- Primary Citation of Related Structures:
1SIP - PubMed Abstract:
A large conformational change is observed between HIV-1 proteinase in the ligand-free state and in complexes with transition-state inhibitors. Crystal structures of this enzyme have either the flaps open for the native or ligand-free enzyme or the flaps closed for peptidomimetic ligand-bound enzyme. We describe the structure of native recombinant SIV proteinase which like other retroviral proteinases crystallizes as a perfect 2-fold symmetric dimer but in a different crystal packing arrangement. In contrast to HIV-1 PR we show that SIV proteinase in the ligand-free state adopts the closed flaps conformation, demonstrating that ligand binding is not a prerequisite for the closed flaps conformation. The catalytic water was clearly observed between the two aspartates which were not perfectly co-planar, and in this structure the active site cleft is more restricted than for either inhibitor bound or ligand-free HIV-1 proteinase. Accommodation of two bulkier side-chains in the simian enzyme core has resulted in a more exposed N terminus than for HIV-1 PR which we predict could enhance autocatalytic cleavage at the N terminus.
Organizational Affiliation:
Department of Crystallography, Birkbeck College, London, England.
