HIV-1 protease is an essential enzyme for viral particle maturation and is a target in the fight against HIV-1 infection worldwide. Several natural polymorphisms are also associated with drug resistance. Here, we utilized both pulsed electron double resonance, also called double electron-electron resonance, and NMR (15)N relaxation measurements to characterize equilibrium conformational sampling and backbone dynamics of an HIV-1 protease construct containing four specific natural polymorphisms commonly found in subtypes A, F, and CRF_01 A/E. Results show enhanced backbone dynamics, particularly in the flap region, and the persistence of a novel conformational ensemble that we hypothesize is an alternative flap orientation of a curled open state or an asymmetric configuration when interacting with inhibitors.
Keywords: Electron Paramagnetic Resonance (EPR); Electron Spin-Label; Flap; HIV-1 Protease; Natural Occurring Polymorphism; Protein Dynamic; Protein Stability; Protein Structure; Pulsed Electron Double Resonance; Salt Bridge.
© 2014 by The American Society for Biochemistry and Molecular Biology, Inc.