Université de Versailles Saint Quentin en Yvelines, INSERM UMR1173, 78000 Versailles, France.
CNRS UMR 9004, Institut de Recherche en Infectiologie de Montpellier, Université de Montpellier, 34293 Montpellier, France.
Proc Natl Acad Sci U S A. 2018 Oct 23;115(43):E10147-E10156. doi: 10.1073/pnas.1812984115. Epub 2018 Oct 9.
is a peculiar rapid-growing (RGM) capable of surviving within eukaryotic cells thanks to an arsenal of virulence genes also found in slow-growing mycobacteria (SGM), such as A screen based on the intracellular survival in amoebae and macrophages (MΦ) of an transposon mutant library revealed the important role of MAB_0855, a yet uncharacterized Mycobacterial membrane protein Large (MmpL). Large-scale comparisons with SGM and RGM genomes uncovered MmpL12 proteins as putative orthologs of MAB_0855 and a locus-scale synteny between the and loci. A KO mutant of the gene, designated herein as , had impaired adhesion to MΦ and displayed a decreased intracellular viability. Despite retaining the ability to block phagosomal acidification, like the WT strain, the mutant was delayed in damaging the phagosomal membrane and in making contact with the cytosol. Virulence attenuation of the mutant was confirmed in vivo by impaired zebrafish killing and a diminished propensity to induce granuloma formation. The previously shown role of MmpL in lipid transport prompted us to investigate the potential lipid substrates of MmpL8 Systematic lipid analysis revealed that MmpL8 was required for the proper expression of a glycolipid entity, a glycosyl diacylated nonadecyl diol (GDND) alcohol comprising different combinations of oleic and stearic acids. This study shows the importance of MmpL8 in modifying interactions between the bacteria and phagocytic cells and in the production of a previously unknown glycolipid family.
是一种奇特的快速生长菌 (RGM)，由于其拥有与缓慢生长分枝杆菌 (SGM) 中相同的毒力基因，因此能够在真核细胞内生存。一种基于在变形虫和巨噬细胞 (MΦ) 内的胞内生存的筛选方法，揭示了 MAB_0855 的重要作用，这是一种尚未被表征的分枝杆菌膜蛋白 Large (MmpL)。与 SGM 和 RGM 基因组的大规模比较揭示了 MmpL12 蛋白是 MAB_0855 的假定直系同源物，以及 和 基因座之间的基因座级同线性。该基因的 KO 突变体，在此命名为 ，其对 MΦ 的粘附能力受损，并且表现出细胞内活力降低。尽管该突变体仍保留了阻断吞噬体酸化的能力，与 WT 菌株一样，但它在破坏吞噬体膜和与细胞质接触方面的速度较慢。在体内通过减弱对斑马鱼的杀伤能力和降低诱导肉芽肿形成的倾向，证实了突变体的毒力减弱。先前的研究表明 MmpL 在脂质转运中的作用促使我们研究 MmpL8 的潜在脂质底物。系统脂质分析表明，MmpL8 是正确表达一种糖脂实体所必需的，该实体是一种糖基二酰基十九烷二醇 (GDND) 醇，包含不同油酸和硬脂酸组合。这项研究表明了 MmpL8 在修饰细菌与吞噬细胞之间的相互作用以及产生以前未知的糖脂家族方面的重要性。
