Mechanics of the IL2RA Gene Activation Revealed by Modeling and Atomic Force MicroscopyReportar como inadecuado

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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.

Autor: Pascale Milani, Monique Marilley, Albert Sanchez-Sevilla, Jean Imbert, Cédric Vaillant, Françoise Argoul, Jean-Marc Egly, José



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