Fiche publication
Date publication
septembre 2020
Journal
The FEBS journal
Auteurs
Membres identifiés du Cancéropôle Est :
Dr SCHULTZ Patrick
,
Dr BEN SHEM Adam
Tous les auteurs :
Ben-Shem A, Papai G, Schultz P
Lien Pubmed
Résumé
In Eukaryotes transcription of protein encoding genes is initiated by the controlled deposition of the TATA-box binding protein TBP onto gene promoters, followed by the ordered assembly of a preinitiation complex. The SAGA co-activator is a 19-subunit complex that stimulates transcription by the action of two chromatin-modifying enzymatic modules, a transcription activator binding module, and by delivering TBP. Recent cryo electron microscopy structures of yeast SAGA with bound nucleosome or TBP reveal the architecture of the different functional domains of the co-activator. An octamer of histone-fold domains is found at the core of SAGA. This octamer, which deviates considerably from the symmetrical analogue forming the nucleosome, establishes a peripheral site for TBP binding where steric hindrance represses interaction with spurious DNA. The structures point to a mechanism for TBP delivery and release from SAGA that requires TFIIA and whose efficiency correlates with the affinity of DNA to TBP. These results provide a structural basis for understanding specific TBP delivery onto gene promoters and the role played by SAGA in regulating gene expression. The properties of the TBP-delivery machine harbored by SAGA are compared with the TBP loading device present in the TFIID complex and show multiple similitudes.
Mots clés
SAGA, TBP loading onto promoters, Transcription, co-activators, cryo-EM
Référence
FEBS J.. 2020 Sep 18;:
