A genetic approach for analyzing the pathway of LamB assembly into the outer membrane of Escherichia coli.
A genetic approach for analyzing the pathway of LamB assembly into the outer membrane of Escherichia coli.
复制标题
DOI：
10.1016/s0021-9258(18)92740-7
复制
发表时间：
1991-07
期刊：
影响因子：
--
通讯作者：
R. Misra;A. Peterson;T. Ferenci;T. Silhavy
中科院分区：
文献类型：
--
作者：
R. Misra;A. Peterson;T. Ferenci;T. Silhavy
本研究中的结果表明，在成熟 LamB 蛋白残基 118 和 119 处的 2 个酪氨酸之间插入额外的酪氨酸的突变会导致温度依赖性组装缺陷。这种缺陷导致中间体在限制温度下积聚，该中间体很可能是组装缺陷单体。这些单体在野生型 (htrA+) 菌株中快速降解，这种降解的双相动力学表明突变影响组装过程，而不影响最终产物，即稳定的三聚体。此外，我们的数据表明，突变株中的温度依赖性组装缺陷是可逆的，因此积累的单体代表了真正的组装中间体。分级研究表明，在限制温度下 htrA (degP) 突变体中可以积累的单体与外膜相关，表明 LamB 三聚化不是定位的先决条件。
Results presented in this study demonstrate that a mutation which inserts an additional tyrosine between the 2 tyrosines at residues 118 and 119 of mature LamB protein results in a temperature-dependent assembly defect. This defect leads to the accumulation of an intermediate at the restrictive temperature that is most likely an assembly-defective monomer. These monomers are rapidly degraded in the wild type (htrA+) strain, and the biphasic kinetics of this degradation indicate that the mutation affects the assembly process and not the final product, i.e. stable trimers. In addition, our data show that the temperature-dependent assembly defect in the mutant strain is reversible, and therefore the accumulated monomers represent a true assembly intermediate. Fractionation studies show that the monomers, which can be accumulated in htrA (degP) mutants at the restrictive temperature, are associated with the outer membrane, indicating that trimerization of LamB is not a prerequisite for localization.