Comparison between TRF2 and TRF1 of their telomeric DNA-bound structures and DNA-binding activities
Comparison between TRF2 and TRF1 of their telomeric DNA-bound structures and DNA-binding activities
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DOI：
10.1110/ps.04983705
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发表时间：
2005-01-01
期刊：
影响因子：
8
通讯作者：
Nishimura, Y
中科院分区：
文献类型：
--
作者：
Hanaoka, S;Nagadoi, A;Nishimura, Y
哺乳动物端粒由端粒DNA结合蛋白TRF 1和TRF 2包装的双链端粒TTAGGG重复序列的长串联阵列组成。两者都含有类似的C-末端Myb结构域，其介导与端粒DNA的序列特异性结合。在TRF 1的DNA复合物中。只有由三个螺旋组成的单个Myb样结构域才能特异性结合双链端粒DNA。TRF 2还结合双链端粒DNA。虽然TRF 2的DNA结合模式可能与TRF 1相同，但TRF 2在保护端粒末端的t环形成中起着重要作用。在这里，为了阐明TRF 1和TRF 2的双链端粒DNA结合模式的细节，我们确定了与端粒DNA结合的人TRF 2的DNA结合结构域的溶液结构;它由三个螺旋组成。与TRF 1一样，第三螺旋识别DNA大沟中的TAGGG序列，N-末端臂位于小沟中。然而，与TRF 1的小沟识别相反，观察到小但显著的差异。其中精氨酸残基识别TT序列，TRF 2的赖氨酸残基与TT部分相互作用。我们研究了TRF 1和TRF 2的DNA结合结构域的端粒DNA结合活性，发现TRF 1比TRF 2结合更强。基于这两个领域的结构差异。我们创建了TRF 2的DNA结合结构域的几种突变体，与野生型TRF 2相比，它们具有更强的结合活性。
Mammalian telomeres consist of long tandem arrays of double-stranded telomeric TTAGGG repeats packaged by the telomeric DNA-binding, proteins TRF1 and TRF2. Both contain a similar C-terminal Myb domain that mediates sequence-specific binding to telomeric DNA. In a DNA complex of TRF1. only the single Myb-like domain consisting of three helices can bind specifically to double-stranded telomeric DNA. TRF2 also binds to double-stranded telomeric DNA. Although the DNA binding mode of TRF2 is likely identical to that of TRF1, TRF2 plays an important role in the t-loop formation that protects the ends of telomeres. Here, to clarify the details of the double-stranded telomeric DNA-binding modes of TRF1 and TRF2, we determined the solution structure of the DNA-binding domain of human TRF2 bound to telomeric DNA; it consists of three helices. and like TRF1, the third helix recognizes TAGGG sequence in the major groove of DNA with the N-terminal arm locating in the minor groove. However, small but significant differences are observed; in contrast to the minor groove recognition of TRF1. in which an arginine residue recognizes the TT sequence, a lysine residue of TRF2 interacts with the TT part. We examined the telomeric DNA-binding activities of both DNA-binding domains of TRF1 and TRF2 and found that TRF1 binds more strongly than TRF2. Based on the structural differences of both domains. we created several mutants of the DNA-binding domain of TRF2 with stronger binding activities compared to the wild-type TRF2.