Institut Pasteur, Université de Paris-Cité, CNRS UMR6047, Genetics of Biofilms Laboratory, Paris, France.
Department of Functional Genomics, Interfaculty Institute for Genetics and Functional Genomics, University Medicine Greifswald, Greifswald, Germany.
Microbiol Spectr. 2023 Aug 17;11(4):e0176723. doi: 10.1128/spectrum.01767-23. Epub 2023 Jun 22.
Many eukaryotic membrane-dependent functions are often spatially and temporally regulated by membrane microdomains (FMMs), also known as lipid rafts. These domains are enriched in polyisoprenoid lipids and scaffolding proteins belonging to the tomatin, rohibitin, lotillin, and flK/C (SPFH) protein superfamily that was also identified in Gram-positive bacteria. In contrast, little is still known about FMMs in Gram-negative bacteria. In Escherichia coli K-12, 4 SPFH proteins, YqiK, QmcA, HflK, and HflC, were shown to localize in discrete polar or lateral inner membrane locations, raising the possibility that E. coli SPFH proteins could contribute to the assembly of inner membrane FMMs and the regulation of cellular processes. Here, we studied the determinant of the localization of QmcA and HflC and showed that FMM-associated cardiolipin lipid biosynthesis is required for their native localization pattern. Using Biolog phenotypic arrays, we showed that a mutant lacking all SPFH genes displayed increased sensitivity to aminoglycosides and oxidative stress that is due to the absence of HflKC. Our study therefore provides further insights into the contribution of SPFH proteins to stress tolerance in E. coli. Eukaryotic cells often segregate physiological processes in cholesterol-rich functional membrane microdomains. These domains are also called lipid rafts and contain proteins of the tomatin, rohibitin, lotillin, and flK/C (SPFH) superfamily, which are also present in prokaryotes but have been mostly studied in Gram-positive bacteria. Here, we showed that the cell localization of the SPFH proteins QmcA and HflKC in the Gram-negative bacterium E. coli is altered in the absence of cardiolipin lipid synthesis. This suggests that cardiolipins contribute to E. coli membrane microdomain assembly. Using a broad phenotypic analysis, we also showed that HflKC contribute to E. coli tolerance to aminoglycosides and oxidative stress. Our study, therefore, provides new insights into the cellular processes associated with SPFH proteins in E. coli.
真核细胞经常将生理过程分隔在富含胆固醇的功能性膜微域中。这些域也称为脂质筏，包含 tomatin、rohibitin、lotillin 和 flK/C（SPFH）超家族的蛋白质，该超家族也存在于原核生物中，但主要在革兰氏阳性菌中进行了研究。在这里，我们表明，在缺乏心磷脂脂质合成的情况下，革兰氏阴性菌大肠杆菌中 SPFH 蛋白 QmcA 和 HflKC 的细胞定位会发生改变。这表明心磷脂有助于大肠杆菌膜微域的组装。通过广泛的表型分析，我们还表明 HflKC 有助于大肠杆菌耐受氨基糖苷类药物和氧化应激。因此，我们的研究为大肠杆菌中与 SPFH 蛋白相关的细胞过程提供了新的见解。
