Three-dimensional structure of the high-potential iron-sulfur protein isolated from the purple phototrophic bacterium Rhodocyclus tenuis determined and refined at 1.5 A resolution.
Three-dimensional structure of the high-potential iron-sulfur protein isolated from the purple phototrophic bacterium Rhodocyclus tenuis determined and refined at 1.5 A resolution.
复制标题
从紫色光养细菌细红环菌中分离出的高电位铁硫蛋白的三维结构以 1.5 A 分辨率测定和精制。
DOI：
10.1016/0022-2836(92)90849-f
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发表时间：
1992
影响因子：
5.6
通讯作者：
Holden,HM
中科院分区：
文献类型：
--
作者：
Rayment,I;Wesenberg,G;Meyer,TE;Cusanovich,MA;Holden,HM
从光养细菌Rhodocyclus tenuis中分离的高电位铁硫蛋白（HiPIP）的分子结构已被解析并细化到1.5 μ m的标称分辨率，对于30 μ m至1.5 μ m的所有测量X射线数据，晶体学R因子为17.3%。它是迄今为止研究的最小的HiPIP结构，具有62个氨基酸残基。研究中使用的晶体属于空间群P2 1，晶胞尺寸为a= 36.7 A，B= 52.6 A，c= 27.6 A，β= 90.8°，每个不对称单元含有两个分子。结构的解决相结合的多个同晶置换与两个重原子衍生物，反常散射的铁硫簇，对称性平均和溶剂平坦。该HiPIP的折叠基序的特征在于一个小α-螺旋、六个I型转角、一个近似II型转角和一个I′型转角。与其他HiPIP一样，铁硫簇由四个半胱氨酰配体协调，并表现出立方烷样基序。这些半胱氨酰配体都位于I型转角中。在R. tenuis蛋白的模式类似于在葡萄色菌和嗜盐外硫红螺菌HiPIP中观察到的模式。几个氨基酸残基不变，在以前确定的C。vinosum和E.嗜盐菌结构在R.细分子两个R之间有13个溶剂分子结构保守。tenuis HiPIP分子的不对称单元，其中一些是重要的稳定表面环。有趣的是，虽然假设该HiPIP在溶液中作为单体起作用，但不对称单元包中的两个分子作为二聚体并且通过近似两倍的旋转轴彼此相关。
The molecular structure of the high-potential iron-sulfur protein (HiPIP) isolated from the phototrophic bacterium, Rhodocyclus tenuis, has been solved and refined to a nominal resolution of 1.5 Å with a crystallographic R-factor of 17.3% for all measured X-ray data from 30 Å to 1.5 Å. It is the smallest of the HiPIP structures studied thus far with 62 amino acid residues. Crystals used in the investigation belonged to the space group P2 1 with unit cell dimensions of a= 36.7 A ̊, b= 52.6 A ̊, c= 27.6 A ̊ and β= 90.8° and contained two molecules per asymmetric unit. The structure was solved by a combination of multiple isomorphous replacement with two heavy-atom derivatives, anomalous scattering from the iron—sulfur cluster, symmetry averaging and solvent flattening. The folding motif for this HiPIP is characterized by one small α-helix, six Type I turns, an approximate Type II turn and one Type I′ turn. As in other HiPIPs, the iron-sulfur cluster is co-ordinated by four cysteinyl ligands and exhibits a cubane-like motif. These cysteinyl ligands are all located in Type I turns. The hydrogen bonding around the metal cluster in the R. tenuis protein is similar to the patterns observed in the Chromatium vinosum and Ectothiorhodospira halophila HiPIPs. Several of the amino acid residues invariant in the previously determined C. vinosum and E. halophila structures are not retained in the R. tenuis molecule. There are 13 solvent molecules structurally conserved between the two R. tenuis HiPIP molecules in the asymmetric unit, some of which are important for stabilizing surface loops. Interestingly, while it is assumed that this HiPIP functions as a monomer in solution, the two molecules in the asymmetric unit pack as a dimer and are related to each other by an approximate twofold rotation axis.