title: Structural and functional insights into IκB-α/HIV-1 Tat interaction.
abstract: Protein-protein interactions play fundamental roles in physiological and pathological biological processes. The characterization of the structural determinants of protein-protein recognition represents an important step for the development of molecular entities able to modulate these interactions. We have recently found that IκB-α (nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha) blocks the HIV-1 expression and replication in a NF-κB-independent manner by directly binding to the virus-encoded Tat transactivator. Here, we report the evaluation of the entity of binding of IκB-α to Tat through in vitro Surface Plasmon Resonance assay. Moreover, by designing and characterizing a set of peptides of the C-terminus region of IκB-α, we show that the peptide corresponding to the IκB-α sequence 262-287 was able to bind to Tat with high affinity (300 nM). The characterization of a number of IκB-α-based peptides also provided insights into their intrinsic folding properties. These findings have been corroborated by mutagenesis studies on the full-length IκB-α, which unveil that different IκB-α residues are involved in NF-κB or Tat recognition.
authors.affiliation: Institute of Biostructures and Bioimaging, CNR, Via Mezzocannone 16, 80134 Naples, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Vitagliano
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Fiume
authors.forename: Pasqualina Liana
authors.initials: PL
authors.lastname: Scognamiglio
authors.forename: Nunzianna
authors.initials: N
authors.lastname: Doti
authors.forename: Rosamaria
authors.initials: R
authors.lastname: Cannavò
authors.forename: Antimina
authors.initials: A
authors.lastname: Puca
authors.forename: Carlo
authors.initials: C
authors.lastname: Pedone
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Scala
authors.forename: Ileana
authors.initials: I
authors.lastname: Quinto
authors.forename: Daniela
authors.initials: D
authors.lastname: Marasco
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D002467:Cell Nucleus / Q000378:metabolism; D015497:HIV-1 / Q000378:metabolism; D020672:I-kappa B Proteins / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism; D013329:Structure-Activity Relationship; D020349:Surface Plasmon Resonance; D054322:tat Gene Products, Human Immunodeficiency Virus / Q000737:chemistry*
chemical_list: D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D054322:tat Gene Products, Human Immunodeficiency Virus; D000072000:NF-KappaB Inhibitor alpha