Hagman J, Gutch M J, Lin H, Grosschedl R
Howard Hughes Medical Institute, Department of Microbiology, University of California, San Francisco 94143-0414, USA.
EMBO J. 1995 Jun 15;14(12):2907-16. doi: 10.1002/j.1460-2075.1995.tb07290.x.
Early B cell factor (EBF) was identified and cloned as a transcription factor expressed specifically in B lymphocytes and adipocytes. This protein was also identified as olfactory factor 1 (Olf-1) in olfactory neurons. In this study, we analyzed the structural requirements for DNA binding, homodimerization and transcriptional activation by EBF. A carboxyl-terminal region, containing a repeat of alpha-helices related to the helix-loop-helix motif, is important for dimerization of EBF in solution and can confer dimerization upon a heterologous DNA binding protein. 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-X3-C-X2-C-X5-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 binding domain that allows for dimerization and transcriptional activation, and additional dimerization and activation domains.
早期B细胞因子（EBF）被鉴定并克隆为一种在B淋巴细胞和脂肪细胞中特异性表达的转录因子。该蛋白在嗅觉神经元中还被鉴定为嗅觉因子1（Olf-1）。在本研究中，我们分析了EBF与DNA结合、同源二聚化及转录激活的结构要求。一个羧基末端区域，包含与螺旋-环-螺旋基序相关的α-螺旋重复序列，对EBF在溶液中的二聚化很重要，并且能赋予异源DNA结合蛋白二聚化能力。氨基末端DNA结合结构域自身是单体形式，但能在优化且正确间隔的半位点上介导二聚体的组装。对EBF DNA结合结构域的突变分析表明，由H-X3-C-X2-C-X5-C组成的新型锌配位基序对DNA识别很重要。缺失分析以及将EBF的区域转移到异源DNA结合结构域上鉴定出一个富含丝氨酸/苏氨酸的转录激活结构域。此外，EBF的DNA结合结构域能从优化的结合位点介导转录激活。因此，EBF既包含一个允许二聚化和转录激活的复杂DNA结合结构域，还包含额外的二聚化和激活结构域。
