Outer membrane protein A of E-coli folds into detergent micelles, but not in the presence of monomeric detergent
Outer membrane protein A of E-coli folds into detergent micelles, but not in the presence of monomeric detergent
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DOI：
10.1110/ps.8.10.2065
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发表时间：
1999-10-01
期刊：
影响因子：
8
通讯作者：
Tamm, LK
中科院分区：
文献类型：
--
作者：
Kleinschmidt, JH;Wiener, MC;Tamm, LK
大肠杆菌的外膜蛋白 A (OmpA) 是一种 β 桶膜蛋白，在 8 M 尿素中展开为随机卷曲，在存在某些去污剂或脂质的情况下，OmpA 在尿素稀释后重新折叠。为了检查β-桶膜蛋白二级和三级结构形成的最低要求，研究了OmpA的折叠作为疏水链长度、极性头基的化学结构和大量两亲物浓度的函数。 OmpA 在去垢剂存在下仅在超过非极性链的临界最小链长时折叠，这是通过圆二色光谱和测量三级结构形成的 SDS-PAGE 测定确定的。极性头基的化学结构细节对于折叠并不重要，折叠所需的最小链长与每个去污剂系列中的临界胶束浓度相关，因此，OmpA需要预先形成的去污剂胶束进行折叠，并且折叠后不会将单体去污剂吸附到其周边。二级和三级结构的形成是热力学耦合的，并且严格依赖于与聚集的两亲物的相互作用。
Outer membrane protein A (OmpA) of Escherichia coli is a beta-barrel membrane protein that unfolds in 8 M urea to a random coil, OmpA refolds upon urea dilution in the presence of certain detergents or lipids. To examine the minimal requirements for secondary and tertiary structure formation in beta-barrel membrane proteins, folding of OmpA was studied as a function of the hydrophobic chain length, the chemical structure of the polar headgroup, and the concentration of a large array of amphiphiles. OmpA folded in the presence of detergents only above a critical minimal chain length of the apolar chain as determined by circular dichroism spectroscopy and a SDS-PAGE assay that measures tertiary structure formation. Details of the chemical structure of the polar headgroup were unimportant for folding, The minimal chain length required for folding correlated with the critical micelle concentration in each detergent series, Therefore, OmpA requires preformed detergent micelles for folding and does not adsorb monomeric detergent to its perimeter after folding, Formation of secondary and tertiary structure is thermodynamically coupled and strictly dependent on the interaction with aggregated amphiphiles.