Structural and functional characterization of the TgDRE multidomain protein, a DNA repair enzyme from Toxoplasma gondii
Structural and functional characterization of the TgDRE multidomain protein, a DNA repair enzyme from Toxoplasma gondii
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DOI：
10.1021/bi051948e
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发表时间：
2006-04-18
期刊：
影响因子：
2.9
通讯作者：
Wolff, N
中科院分区：
文献类型：
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作者：
Frénal, K;Callebaut, I;Wolff, N
寄生虫弓形虫表达一种55 kDa的蛋白质或TgDRE，其属于一个新的蛋白质家族，其特征在于存在三个结构域：人剪接因子45样基序（SF）、富含甘氨酸基序（G-补丁）和RNA识别基序（RRM）。后两个结构域主要被称为RNA结合结构域，并且它们在TgDRE中的存在，其部分DNA修复功能被证明，表明该蛋白质也可能参与RNA代谢。在这项工作中，我们的特点是不同的结构域的结构和功能，通过使用单或多结构域蛋白质，以确定其假定的作用。SF 45样结构域具有螺旋构象，并参与蛋白质的寡聚化。G-补丁结构域，主要是非结构化本身以及在SF上游和RRM下游结构域的存在下，能够结合小RNA寡核苷酸。我们还报告了从NMR数据的RRM域的结构测定。它采用经典的β-α-β-β-α-β拓扑结构，由一个四链β片层组成，对两个α螺旋进行包装，但不存在RNA相互作用的关键残基。相反，我们的分析表明，TgDRE的RRM不仅不能结合小RNA寡核苷酸，但它也与U2 AF异二聚体剪接因子的两个不寻常的RRM共享蛋白质-蛋白质相互作用特征。RNA和蛋白质结合域的存在似乎表明TgDRE也可能参与RNA代谢。
The parasite Toxoplasma gondii expresses a 55 kDa protein or TgDRE that belongs to a novel family of proteins characterized by the presence of three domains, a human splicing factor 45-like motif (SF), a glycine-rich motif (G-patch), and a RNA recognition motif (RRM). The two latter domains are mainly known as RNA-binding domains, and their presence in TgDRE, whose partial DNA repair function was demonstrated, suggests that the protein could also be involved in the RNA metabolism. In this work, we characterized the structure and function of the different domains by using single or multidomain proteins to define their putative role. The SF45-like domain has a helical conformation and is involved in the oligomerization of the protein. The G-patch domain, mainly unstructured on its own as well as in the presence of the SF upstream and RRM downstream domains, is able to bind small RNA oligonucleotides. We also report the structure determination of the RRM domain from the NMR data. It adopts a classical beta alpha beta beta alpha beta topology consisting of a four-stranded beta sheet packed against two alpha helices but does not present the key residues for the RNA interaction. In contrast, our analysis shows that the RRM of TgDRE is not only unable to bind small RNA oligonucleotides but it also shares the protein-protein interaction characteristics with two unusual RRMs of the U2AF heterodimeric splicing factor. The presence of both RNA- and protein-binding domains seems to indicate that TgDRE Could also be involved in RNA metabolism.