Three-Dimensional Domain Swapping in Nitrollin, a Single-Domain βγ-Crystallin from Nitrosospira multiformis, Controls Protein Conformation and Stability but Not Dimerization
Three-Dimensional Domain Swapping in Nitrollin, a Single-Domain βγ-Crystallin from Nitrosospira multiformis, Controls Protein Conformation and Stability but Not Dimerization
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DOI：
10.1016/j.jmb.2008.10.035
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发表时间：
2009-01-09
影响因子：
5.6
通讯作者：
Sankaranarayanan, Rajan
中科院分区：
文献类型：
--
作者：
Aravind, Penmatsa;Suman, Shashi Kumar;Sankaranarayanan, Rajan
β-γ-晶状体蛋白超家族具有良好表征的蛋白质折叠，在原核和真核世界中都发现了几个成员。它们中的大多数含有两个β γ-晶体蛋白结构域。一些例子，如玻璃海鞘晶体蛋白和球蛋白3a，存在代表这个超家族的真核单结构域蛋白。本研究报告的高分辨率晶体结构的单域β-γ-晶体蛋白，nitrillin，从铵氧化土壤细菌多形亚硝化螺菌。尽管序列同一性非常低，但结构保留了特征性的β γ-晶状体蛋白折叠。该蛋白表现出一个独特的情况下，在β-γ-晶体蛋白的同源二聚体，采用其N-末端延伸进行三维（3D）结构域交换与其合作伙伴。交换链的去除导致结构和稳定性的部分损失，但不是二聚化本身，如使用凝胶过滤和平衡解折叠研究所确定的。总的来说，nitrillin代表了一个独特的单结构域原核成员，它已经进化出一种在β-γ-晶体蛋白领域中迄今未知的专门的二聚化模式。(C)2008爱思唯尔有限公司保留所有权利。
The beta gamma-crystallin superfamily has a well-characterized protein fold, with several members found in both prokaryotic and eukaryotic worlds. A majority of them contain two beta gamma-crystallin domains. A few examples, such as ciona crystallin and spherulin 3a exist that represent the eukaryotic single-domain proteins of this superfamily. This study reports the high-resolution crystal structure of a single-domain beta gamma-crystallin protein, nitrollin, from the ammonium-oxidizing soil bacterium Nitrosospira multiformis. The structure retains the characteristic beta gamma-crystallin fold despite a very low sequence identity. The protein exhibits a unique case of homodimerization in beta gamma-crystallins by employing its N-terminal extension to undergo three-dimensional (3D) domain swapping with its partner. Removal of the swapped strand results in partial loss of structure and stability but not dimerization per se as determined using gel filtration and equilibrium unfolding studies. Overall, nitrollin represents a distinct single-domain prokaryotic member that has evolved a specialized mode of dimerization hitherto unknown in the realm of beta gamma-crystalfins. (C) 2008 Elsevier Ltd. All rights reserved.