Identification of the enhancer binding protein MBF-1 of the sea urchin modulator alpha-H2A histone gene.
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.
Alessandro
Claudia
C
Dipartimento di Biologia Cellulare e dello Sviluppo Alberto Monroy, Viale delle Scienze Parco d'Orleans II, Palermo 90128, Italy.
Di Simone
Paola
P
Buscaino
Alessia
A
Anello
Letizia
L
Palla
Franco
F
Spinelli
Giovanni
G
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D018076:DNA, Complementary; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017930:Genes, Reporter; D006657:Histones / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D012617:Sea Urchins / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000378:metabolism
D017931:DNA Primers; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D006657:Histones; D015534:Trans-Activators