The first crystal structure of hyperthermostable NAD-dependent glutamate dehydrogenase from Pyrobaculum islandicum
The first crystal structure of hyperthermostable NAD-dependent glutamate dehydrogenase from Pyrobaculum islandicum
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DOI：
10.1016/j.jmb.2004.10.063
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发表时间：
2005-01-14
影响因子：
5.6
通讯作者：
Tsuge, H
中科院分区：
文献类型：
--
作者：
Bhuiya, MW;Sakuraba, H;Tsuge, H
从Crenarchaeota的Pyrobaculum islandicum中提取了一种极端耐热的NAD依赖的谷氨酸脱氢酶（NAD-GluDH），并对其进行了晶体结构测定。铅的同六聚体结构。溶解islandicum谷氨酸脱氢酶（Pis-GluDH），并以2.9埃的分辨率精制，晶体学R因子为19.9%（无R 26.0%）。结构表明，每个亚基由两个结构域组成，两个结构域被含有活性位点的深裂分开。该酶的二级结构元件和催化重要残基在来自其他来源的NAD（P）依赖性GluDH中高度保守。Pis-GluDH与其他NAD（P）依赖性GluDH的结构比较表明，这种酶的α 8-环-α 9区域的显著差异与其辅酶特异性有关。从三维结构的分析，亚基间的疏水相互作用被发现是酶寡聚化的重要特征。据报道，Pis-GluDH是高度热稳定的，像超嗜热古菌的GluDH。Pyrococcus furiosus，和亚基间离子对网络的增加是负责极端的热稳定性的Pc。狂热酶然而，Pis-GluDH分子中的亚基间离子对的数量远小于Pc。furiosus GluDH。在亚基间界面的疏水相互作用的数量增加，并负责极高的热稳定性。这表明GluDH的高热稳定性的主要分子策略对于每个超嗜热菌可能是不同的。(C)2004爱思唯尔有限公司保留所有权利。
The extremely thermostable NAD-dependent glutamate dehydrogenase (NAD-GluDH) from Pyrobaculum islandicum, a member of the Crenarchaeota, was crystallized, and its 3D structure has been determined by X-ray diffraction methods. The homohexameric structure of Pb. islandicum glutamate dehydrogenase (Pis-GluDH) was solved and refined at a resolution of 2.9 Angstrom with a crystallographic R-factor of 19.9% (R-free 26.0%). The structure indicates that each subunit consists of two domains separated by a deep cleft containing an active site. The secondary structural elements and catalytically important residues of the enzyme were highly conserved among the NAD(P)-dependent GluDHs from other sources. A structural comparison of Pis-GluDH with other NAD(P)-dependent GluDHs suggests that a significant difference in the alpha8-loop-alpha9 region of this enzyme is associated with its coenzyme specificity. From the analysis of the 3D structure, hydrophobic interactions between intersubunits were found to be important features for the enzyme oligomerization. It has been reported that Pis-GluDH is highly thermostable, like the GluDH of the hyperthermophilic archaeum. Pyrococcus furiosus, and the increase in the intersubunit ion pair networks is responsible for the extreme thermostability of the Pc. furiosus enzyme. However, the number of intersubunit ion pairs in the Pis-GluDH molecules is much smaller than those of the Pc. furiosus GluDH. The number of hydrophobic interactions at the intersubunit interfaces were increased and responsible for the extremely high thermostability. This indicates that the major molecular strategy for high thermostability of the GluDHs may be different for each hyperthermophile. (C) 2004 Elsevier Ltd. All rights reserved.