1sip
ALTERNATIVE NATIVE FLAP CONFORMATION REVEALED BY 2.3 ANGSTROMS RESOLUTION STRUCTURE OF SIV PROTEINASE
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| , resolution 2.3Å | |||||||
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| Resources: | FirstGlance, OCA, PDBsum, RCSB | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
OverviewOverview
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 StructureAbout this Structure
1SIP is a Single protein structure of sequence from Simian immunodeficiency virus. Full crystallographic information is available from OCA.
ReferenceReference
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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