Structure of a putative 2′-5′ RNA ligase from Pyrococcus horikoshii
Structure of a putative 2′-5′ RNA ligase from Pyrococcus horikoshii
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DOI：
10.1107/s0907444905017841
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发表时间：
2005-09-01
影响因子：
2.2
通讯作者：
Tahirov, HT
中科院分区：
文献类型：
--
作者：
Rehse, PH;Tahirov, HT
环状磷酸二酯酶和2 '-5' RNA连接酶是具有结构相似性的蛋白质超家族的成员，即使它们的同源性可能非常低。从Pyrococcus horikoshii中分离出一种2 ′-5 ′ RNA连接酶，其晶体结构为2.4埃。蛋白质晶体属正交晶系，空间群为P2（1）2（1）2（1），晶胞参数a = 44.07，B = 45.47，c = 93.17埃，非对称单元中有一个蛋白质单体。分子置换探针是来自嗜热栖热菌的2 '-5' RNA连接酶，其具有30%的序列同一性。该P. horikoshii RNA连接酶具有一些结构特征，这些结构特征与拟南芥的环状磷酸二酯酶更相似，但与拟南芥的环状磷酸二酯酶没有显著的同源性，然而静电表面电位的检查清楚地确定了其与T.嗜热菌RNA连接酶。然而，活性位点裂缝的大小比T小，带的正电荷也少。嗜热菌同源物，这表明实际的基板可能小于先前假定的后者。
Cyclic phosphodiesterase and 2'-5' RNA ligase are members of a superfamily of proteins which share structural similarities even though their homology may be very low. A putative 2'-5' RNA ligase from Pyrococcus horikoshii has been crystallized and its X-ray crystallographic structure determined to 2.4 angstrom. The protein crystallized in the orthorhombic space group P2(1)2(1)2(1), with unit-cell parameters a = 44.07, b = 45.47, c = 93.17 angstrom and one protein monomer in the asymmetric unit. The molecular-replacement probe was a 2'-5' RNA ligase from Thermus thermophilus which shares 30% sequence identity. The P. horikoshii RNA ligase has some structural features that have more in common with a cyclic phosphodiesterase from Arabidopsis thaliana with which it has no significant homology, yet an examination of the electrostatic surface potential clearly defines its relationship to the T. thermophilus RNA ligase. However, the size of the active-site cleft is smaller and less positively charged than that of the T. thermophilus homologue, suggesting that the actual substrate may be smaller than that previously postulated for the latter.