Structural approach to a novel tandem repeat DNA-binding domain, STPR, by CD and NMR.
Structural approach to a novel tandem repeat DNA-binding domain, STPR, by CD and NMR.
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DOI：
10.1021/bi061780c
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发表时间：
2007-02
期刊：
影响因子：
2.9
通讯作者：
Shin Saito;T. Aizawa;K. Kawaguchi;T. Yamaki;Daisuke Matsumoto;M. Kamiya;Y. Kumaki;M. Mizuguchi
中科院分区：
文献类型：
--
作者：
Shin Saito;T. Aizawa;K. Kawaguchi;T. Yamaki;Daisuke Matsumoto;M. Kamiya;Y. Kumaki;M. Mizuguchi
丝素调节剂结合蛋白1(FMBP-1)是一种结合丝素基因转录激活元件的因子。它具有一种新的结构，由四个串联重复序列(R1-R4)组成，每个串联重复序列在C末端的一半含有23个氨基酸。这个区域被称为STPR(Score and Three氨基酸肽重复)结构域，在FMBP-1中作为DNA结合域。有趣的是，这四个重复序列之间的同源性非常高。在这里，我们已经通过核磁共振确定了四个重复序列的三维结构。所有四个重复单位基本上具有相同的结构：N-末端的一半由盐桥和N-帽盒维持的短的α-螺旋。CD研究表明，STPR的全长结构域在溶液中为31%的螺旋。这是由核磁共振分别确定的四个短螺旋之间的连接来解释的。从热变性研究可以推测，这四个螺旋在全长的STPR结构域中可以灵活移动，它们之间没有相互作用。然而，特定的DNA导致全长STPR结构域的α-螺旋含量显著增加，最高可达76%。这一发现表明，全长的STPR结构域与特定的DNA结合会导致诱导适配的构象变化，从而增加α螺旋性；蛋白质结构不佳的区域可能会形成规则的二级结构。此外，突变分析表明，STPR结构域的四个重复以不同的方式增加了与DNA相互作用的可能性。
Fibroin-modulator-binding protein 1 (FMBP-1) is a factor that binds the transcriptional activation elements of the fibroin gene. It has a novel structure, consisting of four tandem repeats (R1-R4) of 23 amino acids each in the C-terminal half. This region is referred to as the STPR (score and three amino acid peptide repeat) domain and acts as a DNA-binding domain in FMBP-1. Interestingly, the homology among the four repeats is remarkably high. Here, we have determined the three-dimensional structures of the four repeats by NMR. All four repeat units have basically the same structure: a short alpha-helix in the N-terminal half maintained by a salt bridge and an N-capping box. CD studies showed that the full-length STPR domain was 31% helical in solution. This is explained by the connections among the four short helices that were determined separately by NMR. From the thermal-denaturation study, it can be deduced that these four helices in the full-length STPR domain moved flexibly with no interaction among them. However, the specific DNA caused a distinct increase, of up to 76%, in the alpha-helical content of the full-length STPR domain. This finding suggests that the binding of the full-length STPR domain to specific DNA causes an induced-fit conformational change that increases alpha-helicity; the poorly structured regions of the protein may form a regular secondary structure. Furthermore, the mutation analysis showed that the four repeats of the STPR domain raise the possibility of interaction with DNA in different ways.