División de Ciencias Naturales y Exactas, Departamento de Biología, Universidad de Guanajuato, Noria Alta s/n, Guanajuato, Gto, 36050, Mexico.
Departamento de Bioingeniería, Escuela de Ingeniería y Ciencias, Tecnológico de Monterrey, Monterrey, Mexico.
Arch Microbiol. 2019 Sep;201(7):999-1008. doi: 10.1007/s00203-019-01670-8. Epub 2019 May 6.
Cellular membrane is a key component for maintaining cell shape and integrity. The classical membrane structure and function by Singer and Nicolson groundbreaking model has depicted the membrane as a homogeneous fluid structure. This view has changed by the discovery of discrete domains containing different lipid compositions, called lipid rafts, which play a key role in signal transduction in eukaryotic cells. In the past few years, lipid raft-like structures have been found in bacteria also, constituted by cardiolipin and other modified lipids, perhaps involved in generating a specific site for protein clustering. Here, we report the analysis of a protein termed YqiK from Escherichia coli, a prohibitin homolog that has been implicated in stress sensing by the formation of membrane-associated microdomains. The E. coli yqiK-deficient mutant strain showed an enhanced swimming behavior and was resistant to ampicillin but its response to other stressing conditions was similar to that of the wild-type strain. The abnormal swimming behavior is reversed when the protein is expressed in trans from a plasmid. Also, we demonstrate that YqiK is not redundant with QmcA, another flotillin homolog found in E. coli. Our results, along with the data available in the literature, suggest that YqiK may be involved in the formation of discrete membrane-associated signaling complexes that regulate and agglomerate signaling proteins to generate cell response to chemotaxis.
细胞膜是维持细胞形状和完整性的关键组成部分。Singer 和 Nicolson 的开创性模型描述了经典的膜结构和功能，将膜描绘为均匀的流体结构。这一观点随着脂质筏等不同脂质组成的离散域的发现而改变，脂质筏在真核细胞信号转导中起着关键作用。在过去的几年中，类似脂筏的结构也在细菌中被发现，由心磷脂和其他修饰脂质组成，可能参与生成蛋白质聚类的特定位点。在这里，我们报告了对大肠杆菌中一种称为 YqiK 的蛋白质的分析，该蛋白质是一种拟菌素同源物，通过形成膜相关的微域参与应激感应。大肠杆菌 yqiK 缺失突变株表现出增强的游动行为，对氨苄青霉素有抗性，但对其他应激条件的反应与野生型菌株相似。当该蛋白从质粒上以反式表达时，异常游动行为会被逆转。此外，我们证明 YqiK 与另一种在大肠杆菌中发现的浮球素同源物 QmcA 不同，后者不是冗余的。我们的结果以及文献中的数据表明，YqiK 可能参与形成离散的膜相关信号复合物，这些复合物调节和聚集信号蛋白，以产生细胞对趋化性的反应。
