Crystal structure of osmoporin OmpC from E-coli at 2.0 Å
Crystal structure of osmoporin OmpC from E-coli at 2.0 Å
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DOI：
10.1016/j.jmb.2006.08.002
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发表时间：
2006-10-06
影响因子：
5.6
通讯作者：
Schirmer, Tilman
中科院分区：
文献类型：
--
作者：
Basle, Arnaud;Rummel, Gabriele;Schirmer, Tilman
孔蛋白在革兰氏阴性菌的外膜上形成跨膜孔，来自大肠杆菌的基质孔蛋白 OmpF 和渗透孔蛋白 OmpC 根据环境条件差异表达。 OmpC 的三维结构已通过 X 射线晶体学确定为 2.0 埃分辨率。正如从高序列相似性中所预期的那样，OmpC 采用类似 OmpF 的 16 链中空 β 桶折叠，并与三个 β 桶相连，形成紧密的三聚体。与 OmpF 不同，由于环 L4 中插入了 14 个残基，细胞外环在三个孔共有的前庭周边形成连续的壁。孔收缩和周质出口与 OmpF 非常相似，保留了 74% 的孔衬里残留物。总体而言，只有很少的可电离残留物在孔内壁处进行交换。 OmpC 结构表明，在生理上区分 OmpC 和 OmpF 的关键参数不是孔径，而是静电孔电势和孔衬里的特定原子细节。 (c) 2006 Elsevier Ltd. 保留所有权利。
Porins form transmembrane pores in the outer membrane of Gram-negative bacteria with matrix porin OmpF and osmoporin OmpC from Escherichia coli being differentially expressed depending on environmental conditions. The three-dimensional structure of OmpC has been determined to 2.0 angstrom resolution by X-ray crystallography. As expected from the high sequence similarity, OmpC adopts the OmpF-like 16-stranded hollow beta-barrel fold with three beta-barrels associated to form a tight trimer. Unlike in OmpF, the extracellular loops form a continuous wall at the perimeter of the vestibule common to the three pores, due to a 14-residues insertion in loop L4. The pore constriction and the periplasmic outlet are very similar to OmpF with 74% of the pore lining residues being conserved. Overall, only few ionizable residues are exchanged at the pore lining. The OmpC structure suggests that not pore size, but electrostatic pore potential and particular atomic details of the pore linings are the critical parameters that physiologically distinguish OmpC from OmpF. (c) 2006 Elsevier Ltd. All rights reserved.