BOB.1 of the channel catfish, Ictalurus punctatus: not a transcriptional coactivator?
BOB.1 of the channel catfish, Ictalurus punctatus: not a transcriptional coactivator?
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斑点叉尾鮰的 BOB.1：不是转录共激活因子？
DOI：
10.1016/j.molimm.2008.10.005
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发表时间：
2009
影响因子：
3.6
通讯作者：
Warr,GregoryW
中科院分区：
文献类型：
--
作者：
Richard,MaraLLennard;Hikima,Jun-ichi;Wilson,MelanieR;Miller,NormanW;Cunningham,Charles;Warr,GregoryW
斑点叉尾（Ictalurus punctatus）免疫球蛋白重链（IGH）基因座的表达受Eμ3′增强子驱动，其核心区包含两个八聚体基序和一个μE5位点。Oct 1和Oct 2转录因子的直向同源物已在癍点叉尾鮰中克隆，并显示与核心增强子内的八聚体基序结合。虽然鲶鱼Oct 2是一个转录激活因子，但鲶鱼Oct 1不能驱动转录，可能是IGH转录的负调节因子。在哺乳动物中，Oct共激活因子BOB. 1（B细胞Oct结合蛋白1，也称为OCA-B和OBF-1）极大地增强了Oct因子的转录活性，在免疫系统的发育中发挥重要作用。BOB.1的直向同源物已在鲶鱼中克隆，并表征了其功能。发现鲶鱼BOB.1的POU结合结构域与人BOB.1的结合结构域在氨基酸水平上95%相同，并且直接参与与Oct-DNA复合物结合的所有残基都是保守的。尽管这种保守性，鲶鱼BOB.1未能增强内源性或共转染鲶鱼Oct 2介导的转录激活，并且未能挽救失活鲶鱼Oct 1的活性。电泳迁移率变动分析表明，鲶鱼BOB.1是能够结合鲶鱼Oct 1和Oct 2时，他们形成了一个复杂的与Oct基序。重组嵌合鲶鱼和人BOB.1蛋白的分析表明，未能驱动转录是由于鲶鱼BOB.1内缺乏功能性激活结构域。
Expression of the immunoglobulin heavy chain (IGH) locus of the channel catfish (Ictalurus punctatus) is driven by the Eμ3′ enhancer, whose core region contains two octamer motifs and a μE5 site. Orthologues of the Oct1 and Oct2 transcription factors have been cloned in the channel catfish and shown to bind to the octamer motifs within the core enhancer. While catfish Oct2 is an activator of transcription, catfish Oct1 failed to drive transcription and may act as a negative regulator of IGH transcription. In mammals, the Oct co-activator BOB.1 (B cell Oct-binding protein1, also known as OCA-B and OBF-1) greatly enhances the transcriptional activity of Oct factors and plays an important role in the development of the immune system. An orthologue of BOB.1 has been cloned in the catfish, and its function characterized. The POU binding domain of the catfish BOB.1 was found to be 95% identical at the amino acid level with the binding domain of human BOB.1, and all the residues directly involved in binding to the Oct-DNA complex were conserved. Despite this conservation, catfish BOB.1 failed to enhance transcriptional activation mediated by endogenous or co-transfected catfish Oct2, and failed to rescue the activity of the inactive catfish Oct1. Electrophoretic mobility shift assays showed that catfish BOB.1 was capable of binding both catfish Oct1 and Oct2 when they formed a complex with the Oct motif. Analysis of recombinant chimeric catfish and human BOB.1 proteins demonstrated that the failure to drive transcription was due to the lack of a functional activation domain within the catfish BOB.1.