title: UV and X-ray structural studies of a 101-residue long Tat protein from a HIV-1 primary isolate and of its mutated, detoxified, vaccine candidate.
abstract: The 101-residue long Tat protein of primary isolate 133 of the human immunodeficiency virus type 1 (HIV-1), wt-Tat(133) displays a high transactivation activity in vitro, whereas the mutant thereof, STLA-Tat(133), a vaccine candidate for HIV-1, has none. These two proteins were chemically synthesized and their biological activity was validated. Their structural properties were characterized using circular dichroism (CD), fluorescence emission, gel filtration, dynamic light scattering, and small angle X-ray scattering (SAXS) techniques. SAXS studies revealed that both proteins were extended and belong to the family of intrinsically unstructured proteins. CD measurements showed that wt-Tat(133) or STLA-Tat(133) underwent limited structural rearrangements when complexed with specific fragments of antibodies. Crystallization trials have been performed on the two forms, assuming that the Tat(133) proteins might have a better propensity to fold in supersaturated conditions, and small crystals have been obtained. These results suggest that biologically active Tat protein is natively unfolded and requires only a limited gain of structure for its function.
authors.affiliation: IBCP UMR CNRS Université de Lyon, IFR, France.
authors.forename: Marine
authors.initials: M
authors.lastname: Foucault
authors.forename: Katia
authors.initials: K
authors.lastname: Mayol
authors.forename: Véronique
authors.initials: V
authors.lastname: Receveur-Bréchot
authors.forename: Marie-Claire
authors.initials: MC
authors.lastname: Bussat
authors.forename: Christine
authors.initials: C
authors.lastname: Klinguer-Hamour
authors.forename: Bernard
authors.initials: B
authors.lastname: Verrier
authors.forename: Alain
authors.initials: A
authors.lastname: Beck
authors.forename: Richard
authors.initials: R
authors.lastname: Haser
authors.forename: Patrice
authors.initials: P
authors.lastname: Gouet
authors.forename: Christophe
authors.initials: C
authors.lastname: Guillon
mesh_terms: D016915:AIDS Vaccines / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D000595:Amino Acid Sequence; D002850:Chromatography, Gel; D002942:Circular Dichroism; D018360:Crystallography, X-Ray; D015497:HIV-1 / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D057927:Hydrophobic and Hydrophilic Interactions; D007128:Immunoglobulin Fragments; D008027:Light; D008744:Methylamines; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry*; D017510:Protein Folding; D012542:Scattering, Radiation; D053838:Scattering, Small Angle; D013056:Spectrophotometry, Ultraviolet; D014270:Trifluoroethanol; D014867:Water; D054322:tat Gene Products, Human Immunodeficiency Virus / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000378:metabolism
chemical_list: D016915:AIDS Vaccines; D007128:Immunoglobulin Fragments; D008744:Methylamines; D050505:Mutant Proteins; C421254:human immunodeficiency virus type 1 Tat vaccine; D054322:tat Gene Products, Human Immunodeficiency Virus; D014867:Water; D014270:Trifluoroethanol; C005855:trimethyloxamine