Sklar Joseph G, Wu Tao, Gronenberg Luisa S, Malinverni Juliana C, Kahne Daniel, Silhavy Thomas J
Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
Proc Natl Acad Sci U S A. 2007 Apr 10;104(15):6400-5. doi: 10.1073/pnas.0701579104. Epub 2007 Apr 2.
A major role of the outer membrane (OM) of Gram-negative bacteria is to provide a protective permeability barrier for the cell, and proper maintenance of the OM is required for cellular viability. OM biogenesis requires the coordinated assembly of constituent lipids and proteins via dedicated OM assembly machineries. We have previously shown that, in Escherichia coli, the multicomponent YaeT complex is responsible for the assembly of OM beta-barrel proteins (OMPs). This complex contains the OMP YaeT and three OM lipoproteins. Here, we report another component of the YaeT complex, the OM lipoprotein small protein A (SmpA). Strains carrying loss-of-function mutations in smpA are viable but exhibit defects in OMP assembly. Biochemical experiments show that SmpA is involved in maintaining complex stability. Taken together, these experiments establish an important role for SmpA in both the structure and function of the YaeT complex.
革兰氏阴性菌外膜（OM）的一个主要作用是为细胞提供保护性的渗透屏障，细胞存活需要外膜的正常维持。外膜生物合成需要通过专门的外膜组装机制协调组装组成脂质和蛋白质。我们之前已经表明，在大肠杆菌中，多组分YaeT复合物负责外膜β桶蛋白（OMPs）的组装。该复合物包含OMP YaeT和三种外膜脂蛋白。在这里，我们报告YaeT复合物的另一个组分，外膜脂蛋白小蛋白A（SmpA）。携带smpA功能丧失突变的菌株是存活的，但在OMP组装方面表现出缺陷。生化实验表明，SmpA参与维持复合物的稳定性。综上所述，这些实验确立了SmpA在YaeT复合物的结构和功能中的重要作用。
