Subtype polymorphisms among HIV-1 protease variants confer altered flap conformations and flexibility.
Human immunodeficiency virus type 1 (HIV-1) protease plays a fundamental role in the maturation and life cycle of the retrovirus HIV-1, as it functions in regulating post-translational processing of the viral polyproteins gag and gag-pol; thus, it is a key target of AIDS antiviral therapy. Accessibility of substrate to the active site is mediated by two flaps, which must undergo a large conformational change from an open to a closed conformation during substrate binding and catalysis. The electron paramagnetic resonance (EPR) method of site-directed spin labeling (SDSL) with double electron-electron resonance (DEER) spectroscopy was utilized to monitor the conformations of the flaps in apo HIV-1 protease (HIV-1PR), subtypes B, C, and F, CRF01_A/E, and patient isolates V6 and MDR 769. The distance distribution profiles obtained from analysis of the dipolar modulated echo curves were reconstructed to yield a set of Gaussian-shaped populations, which provide an analysis of the flap conformations sampled. The relative percentages of each conformer population described as "tucked/curled", "closed", "semi-open", and "wide-open" were determined and compared for various constructs. The results and analyses show that sequence variations among subtypes, CRFs, and patient isolates of apo HIV-1PR alter the average flap conformation in a way that can be understood as inducing shifts in the relative populations, or conformational sampling, of the previously described four conformations for HIV-1PR.
Department of Chemistry, P.O. Box 117200, University of Florida, Gainesville, Florida 32611-7200, USA.
Jamie L
JL
Kear
Mandy E
ME
Blackburn
Angelo M
AM
Veloro
Ben M
BM
Dunn
Gail E
GE
Fanucci
D020134:Catalytic Domain; D016333:HIV Protease / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D017320:HIV Protease Inhibitors / Q000494:pharmacology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D011110:Polymorphism, Genetic
D017320:HIV Protease Inhibitors; D007527:Isoenzymes; D016333:HIV Protease; C514803:p16 protease, Human immunodeficiency virus 1