title: Analysis of the molecular mechanisms underlying the activity of the Ets-1/USF-1 transcription facotr complex on the HIV-1 LTR
creator: Mayer, Ulrich
subject: ddc-570
subject: 570 Life sciences
description: To assure cell type specific gene transcription cells have developed strategies to control the transcription of a large number of genes with a limited number of transcription factors. This is achieved by combinatorial control in which a complex array of transcription factors regulates promoters and enhancers. Recognition of regulatory elements is governed by both protein-DNA and protein-protein interactions. Many transcription factors can engage in multiple protein-protein interactions that form larger complexes required for adequate gene expression. In this PhD thesis I will present results that illuminate the multifaceted interplay between the transcription factors Ets-1 and USF-1. The ETS proteins act synergistically with a variety of other transcription factors to regulate many cellular and viral promoters and enhancers. Transcription of human immunodeficiency virus 1 (HIV-1), integrated into the host cell genome, also depends on the concerted action of cellular and viral transcription factors recruited to the HIV-1 long terminal repeat (LTR). The cellular transcription factors Ets-1 and USF-1 have been shown to form a complex on adjacent DNA binding sites present in the distal enhancer of the HIV-1 provirus and to cooperate in DNA binding and transactivation. DNA binding of Ets-1 is governed by autoinhibition that is exerted by two distinct inhibitory modules situated N- and C-terminally to the ETS DNA binding domain. The objective of my thesis project was to unravel the molecular mechanisms that govern the cooperation between Ets-1 and USF-1. I could show that USF-1 interacts with the C-terminal autoinhibitory module of Ets-1 and that this interaction is required to relieve autoinhibition of Ets-1 DNA binding. Reciprocally DNA binding by USF-1 is also facilitated by interaction with Ets-1. Furthermore, I provide evidence that synergistic transactivation by Ets-1 and USF-1 is not only the consequence of increased DNA binding potential but of additional cooperative mechanisms that affect transactivation function itself. I could reveal a novel mechanism of transcription factor cooperativity by showing that the C-terminal autoinhibitory module of Ets-1 can directly activate transactivation capacity of USF-1. In addition, I show that the transcriptional cofactor CBP is implicated in the mediation of Ets-1/USF-1 cooperativity. CBP interacts physically with both transcription factors and is required for synergistic transactivation. I could map the domain in USF-1 necessary for interaction with CBP to a stretch of 22 amino acids. Deletion of this domain abolishes both transactivation capacity of USF-1 on the HIV-1 LTR reporter and cooperativity with Ets-1. Together, these data provide new insights into the molecular mechanisms underlying Ets-1/USF-1 cooperativity. They indicate that transcription factor interaction results in significant conformational changes that affect both DNA binding and transactivation function of the complex. The example of Ets-1 and USF-1 could serve as a model for the hypothesis that transcription factors do not act as individual entities but that their functionality is only revealed in the complex with other partner molecules, similar to other multiprotein machineries in the cell. 
date: 2004
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/10221/1/Dissertation_Ulrich_Mayer.pdf
identifier: DOI:10.11588/heidok.00010221
identifier: urn:nbn:de:bsz:16-opus-102213
identifier:   Mayer, Ulrich  (2004) Analysis of the molecular mechanisms underlying the activity of the Ets-1/USF-1 transcription facotr complex on the HIV-1 LTR.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/10221/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng