Novel factors required for OM integrity.

(A) Genetic interaction sub-network in rich medium. (B) Aggravating interactions between lptD and yfgH, yceK, and ytfN. (C) Proposed mechanism of drug hypersensitivity (I) modeled on [68]: envelope deficiency results in a porous OM (dashes), thereby allowing vancomycin (VAN) into the periplasm where it blocks PG cross-linking, weakening the cell wall and resulting in cytoplasmic membrane bulges in single mutant strains (II) or catastrophic cell wall failure and lysis in double mutants (III); scale bar equals 2 µm. Quantification (percentage) of bulged or lysed cells following vancomycin treatment according to strain genotype; error bars indicate standard deviation (IV). (D) Growth inhibition of strains treated with vancomycin. Graph shows mean drug disk halo diameter and standard deviation (error bars) in three independent experiments; p-value calculated using Student's t-test. (E) SDS-PAGE immunoblot analyses of marker protein levels in indicated strains during logarithmic growth in rich medium; periplasmic maltose-binding protein (MBP) used as loading control.(A) 丰富培养基中的遗传相互作用子网（genetic interaction sub-network）。(B) lptD与yfgH、yceK及ytfN之间的加重型相互作用。(C) 参照文献[68]构建的药物超敏性拟议机制：(I) 包膜缺陷导致外膜（Outer Membrane, OM）呈多孔状态（以虚线标注），使万古霉素（vancomycin, VAN）得以进入周质空间，阻断肽聚糖（Peptidoglycan, PG）交联反应，削弱细胞壁强度；单突变菌株会因此出现细胞质膜凸起(II)，双突变菌株则会发生严重的细胞壁破裂与细胞裂解(III)；比例尺为2 µm。(IV) 按菌株基因型分类，统计万古霉素处理后凸起或裂解细胞的百分比，误差棒代表标准差（standard deviation）。(D) 受试菌株经万古霉素处理后的生长抑制实验。图表展示了三次独立实验中药物纸片抑菌圈直径的均值与标准差（误差棒），p值通过学生t检验（Student's t-test）计算得出。(E) 对丰富培养基中对数生长期的指定菌株的标记蛋白表达水平进行SDS-聚丙烯酰胺凝胶电泳免疫印迹（SDS-PAGE immunoblot）分析；以周质空间麦芽糖结合蛋白（maltose-binding protein, MBP）作为上样对照。