Alessandro Claudia, Di Simone Paola, Buscaino Alessia, Anello Letizia, Palla Franco, Spinelli Giovanni
Dipartimento di Biologia Cellulare e dello Sviluppo Alberto Monroy, Viale delle Scienze Parco d'Orleans II, Palermo 90128, Italy.
Biochem Biophys Res Commun. 2002 Jul 12;295(2):519-25. doi: 10.1016/s0006-291x(02)00708-8.
The modulator of the sea urchin alpha-H2A histone gene promoter is the only enhancer identified in the alpha-histone gene cluster. Binding of a single factor, denoted MBF-1, has previously detected in nuclear extracts from morula and gastrula embryos. Here, we describe the cloning of MBF-1 by screening a cDNA expression library with a tandem array of modulator binding sites. MBF-1 presents no similarity with other DNA binding proteins and contains nine Krüppel like Zn fingers. In vitro translated proteins and a factor from nuclear extracts interact with the modulator with identical specificity. In addition, MBF-1 expressed in human cells transactivates a reporter gene driven by an array of modulator sites. The DNA binding domain consists of the Zn fingers plus an adjacent basic region, while sequences in the N-terminal region mediates the transactivation function. MBF-1 is expressed in the unfertilized egg and in early and late developmental stages thus confirming that it is not a stage specific enhancer binding factor and that silencing of the alpha-H2A gene after hatching is not due to the lack of the transactivator.
