title: Mechanics of the IL2RA gene activation revealed by modeling and atomic force microscopy.
abstract: Transcription implies recruitment of RNA polymerase II and transcription factors (TFs) by DNA melting near transcription start site (TSS). Combining atomic force microscopy and computer modeling, we investigate the structural and dynamical properties of the IL2RA promoter and identify an intrinsically negative supercoil in the PRRII region (containing Elf-1 and HMGA1 binding sites), located upstream of a curved DNA region encompassing TSS. Conformational changes, evidenced by time-lapse studies, result in the progressive positioning of curvature apex towards the TSS, likely facilitating local DNA melting. In vitro assays confirm specific binding of the General Transcription Factors (GTFs) TBP and TFIIB over TATA-TSS position, where an inhibitory nucleosome prevented preinitiation complex (PIC) formation and uncontrolled DNA melting. These findings represent a substantial advance showing, first, that the structural properties of the IL2RA promoter are encoded in the DNA sequence and second, that during the initiation process DNA conformation is dynamic and not static.
authors.affiliation: RGFCP EA 3290, Faculté de Médecine, Marseille, France.
authors.forename: Pascale
authors.initials: P
authors.lastname: Milani
authors.forename: Monique
authors.initials: M
authors.lastname: Marilley
authors.forename: Albert
authors.initials: A
authors.lastname: Sanchez-Sevilla
authors.forename: Jean
authors.initials: J
authors.lastname: Imbert
authors.forename: Cédric
authors.initials: C
authors.lastname: Vaillant
authors.forename: Françoise
authors.initials: F
authors.lastname: Argoul
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Egly
authors.forename: José
authors.initials: J
authors.lastname: Rocca-Serra
authors.forename: Alain
authors.initials: A
authors.lastname: Arneodo
mesh_terms: D004247:DNA / Q000235:genetics; D006801:Humans; D053645:Interleukin-2 Receptor alpha Subunit / Q000235:genetics*; D018625:Microscopy, Atomic Force; D008962:Models, Theoretical; D011401:Promoter Regions, Genetic
chemical_list: C508017:IL2RA protein, human; D053645:Interleukin-2 Receptor alpha Subunit; D004247:DNA