Alternative Native Flap Conformation Revealed by 2·3 Å Resolution Structure of SIV Proteinase

Wilderspin, A.F. and Sugrue, R.J. (1994) Alternative Native Flap Conformation Revealed by 2·3 Å Resolution Structure of SIV Proteinase. Journal of Molecular Biology, 239 (1). pp. 97-103. 10.1006/jmbi.1994.1353.

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DOI: 10.1006/jmbi.1994.1353


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-bond enzyme. We describe the structure of native recombinant SIV proteinase which like other retroviral proteinases crytallizes 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 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.

Item Type:Article
Uncontrolled Keywords:SIV proteinase; flap conformation; retroviral proteinase; AIDS; X-ray structure
Departments, units and centres:Department of Pharmacology > Department of Pharmacology
ID Code:3147
Journal or Publication Title:Journal of Molecular Biology
Deposited By:Library Staff
Deposited On:03 May 2012 14:23
Last Modified:03 May 2012 14:23

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