title: Modulation of HIV protease flexibility by the T80N mutation.
abstract: The flexibility of HIV protease (HIVp) plays a critical role in enabling enzymatic activity and is required for substrate access to the active site. While the importance of flexibility in the flaps that cover the active site is well known, flexibility in other parts of the enzyme is also critical for function. One key region is a loop containing Thr 80, which forms the walls of the active site. Although not situated within the active site, amino acid Thr80 is absolutely conserved. The mutation T80N preserves the structure of the enzyme but catalytic activity is completely lost. To investigate the potential influence of the T80N mutation on HIVp flexibility, wide-angle X-ray scattering (WAXS) data was measured for a series of HIVp variants. Starting with a calculated WAXS pattern from a rigid atomic model, the modulations in the intensity distribution caused by structural fluctuations in the protein were predicted by simple analytic methods and compared with the experimental data. An analysis of T80N WAXS data shows that this variant is significantly more rigid than the WT across all length scales. The effects of this single point mutation extend throughout the protein, to alter the mobility of amino acids in the enzymatic core. These results support the contentions that significant protein flexibility extends throughout HIVp and is critical to catalytic function.
authors.affiliation: Department of Electrical and Computer Engineering, Northeastern University, Boston, Massachusetts.
authors.forename: Hao
authors.initials: H
authors.lastname: Zhou
authors.affiliation: Department of Electrical and Computer Engineering, Northeastern University, Boston, Massachusetts.
authors.forename: Shangyang
authors.initials: S
authors.lastname: Li
authors.affiliation: DeltaG Technologies, San Diego, California.
authors.forename: John
authors.initials: J
authors.lastname: Badger
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts.
authors.forename: Ellen
authors.initials: E
authors.lastname: Nalivaika
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts.
authors.forename: Yufeng
authors.initials: Y
authors.lastname: Cai
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Foulkes-Murzycki
authors.affiliation: Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts.
authors.forename: Celia
authors.initials: C
authors.lastname: Schiffer
authors.affiliation: Department of Bioengineering, Northeastern University, Boston, Massachusetts.|Department of Chemistry and Chemical Biology, Northeastern University, Boston, Massachusetts.
authors.forename: Lee
authors.initials: L
authors.lastname: Makowski
mesh_terms: D016333:HIV Protease / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D056004:Molecular Dynamics Simulation; D009154:Mutation; D018583:Pliability; D014961:X-Ray Diffraction
chemical_list: D016333:HIV Protease
keywords: molecular dynamics simulation; protein flexibility; x-ray solution scattering