Regulation of activity of the yeast TATA-binding protein through intra-molecular interactions
Regulation of activity of the yeast TATA-binding protein through intra-molecular interactions
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DOI：
10.1007/bf02705116
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发表时间：
2003-06-01
影响因子：
2.9
通讯作者：
Bhargava, P
中科院分区：
文献类型：
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作者：
Vanathi, P;Mishra, AK;Bhargava, P
二聚化被认为是TATA结合蛋白（TBP）在体内外活性的调节机制。TBP的可逆二聚体-单体转变受体外缓冲条件的影响。使用体外化学交联，我们发现酵母TBP（yTBP）在二价阳离子Mg 2+的存在下，即使在高盐浓度下，在很大程度上是单体的。yTBP的表观分子量在高盐与Mg 2+，通过凝胶过滤柱运行，是接近的单体yTBP。在不存在Mg 2+的情况下降低单价离子浓度，导致TBP的二聚化。在两个不同的水平上观察到Mg 2+的作用：在较高的TBP浓度下，它抑制TBP二聚化，在较低的TBP水平下，它有助于保持TBP单体处于活性构象（能够结合TATA盒），导致在增加的Mg 2+存在下增强的TBP-TATA复合物形成。在这两个水平上，在Mg 2+存在下全长TBP的活性与所报道的N-末端被去除的截短的TBP的C-末端结构域相似。因此，对于全长TBP，分子内相互作用可以通过类似的机制调节其活性。
Dimerization is proposed to be a regulatory mechanism for TATA-binding protein (TBP) activity both in vitro and in vivo. The reversible dimer-monomer transition of TBP is influenced by the buffer conditions in vitro. Using in vitro chemical cross-linking, we found yeast TBP (yTBP) to be largely monomeric in the presence of the divalent cation Mg2+, even at high salt concentrations. Apparent molecular mass of yTBP at high salt with Mg2+, run through a gel filtration column, was close to that of monomeric yTBP. Lowering the monovalent ionic concentration in the absence of Mg2+, resulted in dimerization of TBP. Effect of Mg2+ was seen at two different levels: at higher TBP concentrations, it suppressed the TBP dimerization and at lower TBP levels, it helped keep TBP monomers in active conformation (competent for binding TATA box), resulting in enhanced TBP-TATA complex formation in the presence of increasing Mg2+. At both the levels, activity of the full-length TBP in the presence of Mg2+ was like that reported for the truncated C-terminal domain of TBP from which the N-terminus is removed. Therefore for full-length TBP, intra-molecular interactions can regulate its activity via a similar mechanism.