title: Two types of zinc fingers are required for dimerization of the serendipity delta transcriptional activator.
abstract: The serendipity (sry) delta zinc finger protein controls bicoid gene expression during Drosophila melanogaster oogenesis. In addition, sry delta mutants display various zygotic phenotypes, ranging from abnormal embryogenesis to sex-biased adult lethality. We report here that sry delta is a sequence-specific transcriptional activator. A single sry delta consensus binding site (SDCS), in either orientation, is sufficient to promote transcription activation in cell culture, and multiple SDCSs mediate a strong synergistic activation, reflecting the cooperativity of sry delta binding to DNA. Further, several lines of evidence strongly suggest that sry delta binds to DNA as a dimer. While each of three point mutations located in the third zinc finger of sry delta drastically reduces its DNA binding affinity, a fourth mutation, located in the N-terminal region of the protein, specifically affects the cooperativity of DNA binding. This mutation reveals the functional importance of a putative Cys2/Cys2 zinc finger motif of a novel type, located outside the DNA binding domain. A systematic deletion analysis shows that interaction between this proposed Cys2/Cys2 motif and a classical Cys2/His2 zinc finger mediates homodimerization, which is required for DNA binding cooperativity.
authors.affiliation: Centre de Biologie du Développement, Toulouse, France. payre@cict.fr
authors.forename: F
authors.initials: F
authors.lastname: Payre
authors.forename: P
authors.initials: P
authors.lastname: Buono
authors.forename: N
authors.initials: N
authors.lastname: Vanzo
authors.forename: A
authors.initials: A
authors.lastname: Vincent
mesh_terms: D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D004247:DNA / Q000378:metabolism; D019281:Dimerization; D029721:Drosophila Proteins; D004331:Drosophila melanogaster; D018507:Gene Expression Regulation, Developmental; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009866:Oogenesis; D014157:Transcription Factors / Q000378:metabolism*; D015533:Transcriptional Activation; D016335:Zinc Fingers
chemical_list: D029721:Drosophila Proteins; C090567:Sry-delta protein, Drosophila; D014157:Transcription Factors; D004247:DNA