title: Room Temperature Neutron Crystallography of Drug Resistant HIV-1 Protease Uncovers Limitations of X-ray Structural Analysis at 100 K.
abstract: HIV-1 protease inhibitors are crucial for treatment of HIV-1/AIDS, but their effectiveness is thwarted by rapid emergence of drug resistance. To better understand binding of clinical inhibitors to resistant HIV-1 protease, we used room-temperature joint X-ray/neutron (XN) crystallography to obtain an atomic-resolution structure of the protease triple mutant (V32I/I47V/V82I) in complex with amprenavir. The XN structure reveals a D+ion located midway between the inner Oδ1 oxygen atoms of the catalytic aspartic acid residues. Comparison of the current XN structure with our previous XN structure of the wild-type HIV-1 protease-amprenavir complex suggests that the three mutations do not significantly alter the drug-enzyme interactions. This is in contrast to the observations in previous 100 K X-ray structures of these complexes that indicated loss of interactions by the drug with the triple mutant protease. These findings, thus, uncover limitations of structural analysis of drug binding using X-ray structures obtained at 100 K.
authors.affiliation: UT/ORNL Joint Institute of Biological Sciences, University of Tennessee , Knoxville, Tennessee 37996, United States.
authors.forename: Oksana
authors.initials: O
authors.lastname: Gerlits
authors.affiliation: ISIS Facility, Rutherford Appleton Laboratory , Harwell Campus, Didcot, OX11 0QX, U.K.
authors.forename: David A
authors.initials: DA
authors.lastname: Keen
authors.affiliation: Large-Scale Structures Group, Institut Laue Langevin , 71 avenue des Martyrs, 38000 Grenoble, France.
authors.forename: Matthew P
authors.identifier: 0000-0002-6412-4358
authors.initials: MP
authors.lastname: Blakeley
authors.affiliation: Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health , DHHS, Bethesda, Maryland 20892-0520, United States.
authors.forename: John M
authors.initials: JM
authors.lastname: Louis
authors.affiliation: Departments of Chemistry and Biology, Georgia State University , Atlanta, Georgia 30302, United States.
authors.forename: Irene T
authors.identifier: 0000-0003-4876-7393
authors.initials: IT
authors.lastname: Weber
authors.affiliation: Biology and Soft Matter Division, Oak Ridge National Laboratory , Oak Ridge, Tennessee 37831, United States.
authors.forename: Andrey
authors.identifier: 0000-0003-4459-9142
authors.initials: A
authors.lastname: Kovalevsky
mesh_terms: D002384:Catalysis; D018360:Crystallography, X-Ray / Q000379:methods*; D016333:HIV Protease / Q000737:chemistry*; D009502:Neutrons; D011487:Protein Conformation
chemical_list: D016333:HIV Protease; C514803:p16 protease, Human immunodeficiency virus 1