革兰氏阴性菌细胞外膜（Outer Membrane, OM）外侧的关键组分脂多糖（Lipopolysaccharide, LPS）是影响致病菌细胞外膜特性的重要毒力因子，但目前对细菌LPS的致病机制缺乏深入研究。该研究首次对大肠杆菌（Escherichia coli）W3110野生菌株和LPS结构突变株ΔwaaC和Δ(lpxL lpxM lpxP)进行差异脂质组学研究，探究LPS结构变化对脂质组的影响。结果表明E. coli的LPS相关结构缺失会显著改变细胞脂质种类和相对含量，这与其OM特性改变密切相关。其中ΔwaaC和Δ(lpxL lpxM lpxP) OM渗透性较W3110提高13.59%~19.00%，细胞膜流动性降低23.71%~32.84%。差异脂质组学显示，W3110鉴定出22亚类416种脂质，2株突变株脂质种类均减少，但出现新脂质CL(14:0/14:0/15:0/12:0)-H，CL(17:3/15:0/12:0/14:0)-H和CL(18:3/12:0/14:0/15:0)-H。此外，2株突变株多数脂质含量变化明显，尤其是单不饱和PE减少3.07%~9.02%，单不饱和CL增加1.11%~1.73%。ΔwaaC与Δ(lpxL lpxM lpxP)脂质组也存在较大差异。该研究揭示LPS结构变化引发脂质种类和相对强度显著改变，这是E. coli的OM特性变化的重要原因。

Lipopolysaccharide (LPS), a key component on the outer side of the outer membrane (OM) of Gramnegative bacteria, is an important virulence factor affecting the characteristics of the outer cell membrane of pathogenic bacteria. However, at present, there is a lack of in-depth research on the pathogenic mechanism of bacterial LPS. In this study, differential lipidomic studies were carried out for the first time on the wild Escherichia coli strain W3110 and its LPS structural mutants ΔwaaC and Δ(lpxL lpxM lpxP), and the effects of LPS structural changes on lipidome. The results indicated that the loss of LPS-related structure in E. coli significantly altered the type and relative content of cell lipids, which was closely related to the change of OM characteristics. Compared with W3110, the permeability of ΔwaaC and Δ(lpxL lpxM lpxP) increased by 13.59% to 19.00%, and the fluidity of the OM decreased by 23.71% to 32.84%. Differential lipidomics revealed that 416 lipids of 22 subclasses were identified in W3110. The types of lipid species of the two mutant strains were reduced, while new lipids such as CL(14:0/14:0/15:0/12:0)-H, CL(17:3/15:0/12:0/14:0)-H, and CL(18:3/12:0/14:0/15:0)-H appeared in both mutants. In addition, most of the lipid contents of the two mutant strains changed significantly, in particular, the monounsaturated PE decreased by 3.07%~9.02%, and the monounsaturated CL increased by 1.11%~1.73%. There were also large differences in lipidome between ΔwaaC and Δ(lpxL lpxM lpxP). This study revealed that the structural changes of LPS resulted in significant alterations in lipid type and relative strength, which was an important factor for the change in the OM characteristics of E. coli.

国家重点研发计划政府间国际科技创新合作项目（2023YFE0104400）