title: Adaptability and flexibility of HIV-1 protease.
abstract: Even though more than 200 three-dimensional structures of HIV-1 protease complexed to a variety of inhibitors are available in the Protein Data Bank; very few structures of unliganded protein have been determined. We have recently solved structures of unliganded HIV-1 protease tethered dimer mutants to resolutions of 1.9 A and 2.1 A, and have found that the flaps assume closed-flap conformation even in the absence of any bound ligand. We report comparison of the unliganded closed-flap structure with structures of HIV-1 protease inhibitor complexes with a view to accurately identifying structural changes that the ligand can induce on binding to HIV-1 protease in the crystal. These studies reveal that the least flexible region present in the active site of HIV-1 protease need not also be the least adaptable to external stress, thus highlighting the conceptual difference between flexibility and adaptability of proteins in general.
authors.affiliation: Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai, India.
authors.forename: Mukesh
authors.initials: M
authors.lastname: Kumar
authors.forename: Madhusoodan V
authors.initials: MV
authors.lastname: Hosur
mesh_terms: D001665:Binding Sites; D018360:Crystallography, X-Ray; D004791:Enzyme Inhibitors / Q000737:chemistry / Q000378:metabolism; D016333:HIV Protease / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D011485:Protein Binding; D011487:Protein Conformation
chemical_list: D004791:Enzyme Inhibitors; D008024:Ligands; D016333:HIV Protease