The serendipity (sry) δ zinc finger protein controls bicoid gene expression during Drosophila melanogaster oogenesis. In addition, sry δ mutants display various zygotic phenotypes, ranging from abnormal embryogenesis to sex-biased adult lethality. We report here that sty δ is a sequence-specific transcriptional activator. A single sry δ 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 δ binding to DNA. Further, several lines of evidence strongly suggest that sry δ binds to DNA as a dimer. While each of three point mutations located in the third zinc finger of sty δ 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 linger 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.
|Number of pages||9|
|Journal||Molecular and Cellular Biology|
|Publication status||Published - Jun 1997|
ASJC Scopus subject areas
- Cell Biology
- Molecular Biology