EBF CONTAINS A NOVEL ZINC COORDINATION MOTIF AND MULTIPLE DIMERIZATION AND TRANSCRIPTIONAL ACTIVATION DOMAINS

Early B cell factor (EBF) was identified and cloned as a transcription factor expressed specifically in B lymphocytes and adipocytes. This p rotein was also identified as olfactory factor 1 (Olf-1) in olfactory neurons, In this study, we analyzed the structural requirements for DN A binding, homodimerization and transcriptional activation by EBF. A c arboxyl-terminal region, containing a repeat of a-helices related to t he helix-loop-helix motif, is important for dimerization of EBF in sol ution and can confer dimerization upon a heterologous DNA binding prot ein, The amino-terminal DNA binding domain by itself is monomeric, but can mediate assembly of dimers on optimized and correctly spaced half -sites, Mutational analysis of the DNA binding domain of EBF indicated that a novel zinc coordination motif consisting of H-X(3)-C-X(2)-C-X( 5)-C is important for DNA recognition, Deletion analysis and transfer of regions of EBF onto a heterologous DNA binding domain identified a serine/threonine-rich transcriptional activation domain, Moreover, the DNA binding domain of EBF can mediate transcriptional activation from optimized binding sites, Thus, EBF contains both a complex DNA bindin g domain that allows for dimerization and transcriptional activation, and additional dimerization and activation domains.