1sip

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spinqualitylabelsall models 1sip, resolution 2.3Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

ALTERNATIVE NATIVE FLAP CONFORMATION REVEALED BY 2.3 ANGSTROMS RESOLUTION STRUCTURE OF SIV PROTEINASE

Overview

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.

About this Structure

1SIP is a Single protein structure of sequence from Simian immunodeficiency virus. Full crystallographic information is available from OCA.

Reference

Alternative native flap conformation revealed by 2.3 A resolution structure of SIV proteinase., Wilderspin AF, Sugrue RJ, J Mol Biol. 1994 May 27;239(1):97-103. PMID:8196050

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