Descripción del proyecto
La estructura del nucleosoma y la transcripción de la cromatina
El nucleosoma representa la parte fundamental de la cromatina y ayuda a compactar el ADN para que encaje en el núcleo celular. La estructura de un nucleosoma consiste en ADN enrollado alrededor de proteínas histonas. Los mecanismos moleculares subyacentes a la transcripción de la cromatina siguen sin conocerse bien, ya que los estudios más importantes se realizaron en ADN desnudo, no en cromatina. El proyecto CHROMATRANS, financiado con fondos europeos, se propone dar los próximos pasos hacia la comprensión del mecanismo de transcripción e investigar la base estructural de la transcripción de la polimerasa II (pol II) de los patrones de cromatina. Los objetivos principales son determinar estructuras de factores de iniciación unidos a nucleosomas, la estructura del complejo de preiniciación de la pol II en el nucleosoma al principio de la transcripción y estructuras del complejo de elongación de la pol II en mamíferos.
Objetivo
Transcription of protein-coding genes by RNA polymerase II (Pol II) governs cell identity and fate. We previously provided the structural basis of Pol II transcription initiation (ERC Advanced Grant TRANSIT: Sainsbury, Nature 2012; Lariviere, Nature 2012, Plaschka, Nature 2015) and of Pol II elongation regulation (ERC Advanced Grant TRANSREGULON: Vos, Nature 2018; Vos & Farnung, Nature 2018). These studies elucidated the mechanisms of transcription regulation. However, they were conducted on naked DNA, and not on chromatin, which is the natural template in cells and regulates transcription in many ways. As a consequence, the molecular mechanism underlying chromatin transcription and the regulatory interplay between chromatin and the transcription machinery remain poorly understood. Here I propose to take the next big step towards an understanding of the transcription mechanism and investigate the structural basis for Pol II transcription of chromatin templates. Integrated structural biology will provide structures of the transcription machinery on nucleosomal DNA. Nucleosomes are the building blocks of chromatin and regulate transcription in many ways. In particular, we will solve structures of pioneer factors bound to nucleosomes, to investigate how chromatin is opened locally for transcription (aim 1). We will solve the structure of the Pol II pre-initiation complex on the ‘+1’ nucleosome at the beginning of a gene, to understand how initiation is regulated by this specialized nucleosome (aim 2). Finally, we will determine structures of mammalian Pol II elongation complexes with many factors during nucleosome passage, to elucidate how Pol II transcribes chromatin (aim 3). Together with functional analysis in vitro and in vivo, these ground-breaking efforts will take the structural biology of transcription regulation to the chromatin level. The proposed research will also advance methods for the reconstitution and analysis of transient, higher-order complexes.
Ámbito científico
Palabras clave
Programa(s)
Régimen de financiación
ERC-ADG - Advanced GrantInstitución de acogida
80539 Munchen
Alemania