title: Cooperative interaction of ets-1 with USF-1 required for HIV-1 enhancer activity in T cells.
abstract: The distal enhancer region of the human immunodeficiency virus 1 (HIV-1) long terminal repeat (LTR) is known to be essential for HIV replication and to contain immediately adjacent E-box and Ets binding sites. Based on a yeast one-hybrid screen we have identified the E-box binding protein USF-1 as a direct interaction partner of Ets-1 and found that the complex acts on this enhancer element. The binding surfaces of USF-1 and Ets-1 map to their DNA-binding domains and although these domains are highly conserved, the interaction is very selective within the respective protein family. USF-1 and Ets-1 synergize in specific DNA binding as well as in the transactivation of reporter constructs containing the enhancer element, and mutations of the individual binding sites dramatically reduce reporter activity in T cells. In addition, a dominant negative Ets-1 mutant inhibits both USF-1-mediated transactivation and the activity of the HIV-1 LTR in T cells. The inhibition is independent of Ets DNA-binding sites but requires the Ets binding surface on USF-1, highlighting the importance of the direct protein-protein interaction. Together these results indicate that the interaction between Ets-1 and USF-1 is required for full transcriptional activity of the HIV-1 LTR in T cells.
authors.affiliation: EMBL, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
authors.forename: M H
authors.initials: MH
authors.lastname: Sieweke
authors.forename: H
authors.initials: H
authors.lastname: Tekotte
authors.forename: U
authors.initials: U
authors.lastname: Jarosch
authors.forename: T
authors.initials: T
authors.lastname: Graf
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D003001:Cloning, Molecular; D004279:DNA, Viral / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005799:Genes, Dominant; D016322:HIV Enhancer / Q000235:genetics*; D015497:HIV-1 / Q000235:genetics* / Q000502:physiology; D018257:Helix-Loop-Helix Motifs; D006801:Humans; D019169:Jurkat Cells; D016350:Leucine Zippers; D008969:Molecular Sequence Data; D009154:Mutation; D050784:Proto-Oncogene Protein c-ets-1; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D050783:Proto-Oncogene Proteins c-ets; D011784:Quail; D011993:Recombinant Fusion Proteins; D013601:T-Lymphocytes / Q000821:virology*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation / Q000502:physiology; D014162:Transfection; D051720:Upstream Stimulatory Factors
chemical_list: D004279:DNA, Viral; D004268:DNA-Binding Proteins; C494041:ETS1 protein, human; D050784:Proto-Oncogene Protein c-ets-1; D011518:Proto-Oncogene Proteins; D050783:Proto-Oncogene Proteins c-ets; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C497181:USF1 protein, human; D051720:Upstream Stimulatory Factors