Centre National de la Recherche Scientifique, Institut de Pharmacologie et de Biologie Structurale, F-31077 Toulouse, France.
Proc Natl Acad Sci U S A. 2013 Apr 16;110(16):6560-5. doi: 10.1073/pnas.1219704110. Epub 2013 Apr 2.
A posttranslational protein O-mannosylation process resembling that found in fungi and animals has been reported in the major human pathogen Mycobacterium tuberculosis (Mtb) and related actinobacteria. However, the role and incidence of this process, which is essential in eukaryotes, have never been explored in Mtb. We thus analyzed the impact of interrupting O-mannosylation in the nonpathogenic saprophyte Mycobacterium smegmatis and in the human pathogen Mtb by inactivating the respective putative protein mannosyl transferase genes Msmeg_5447 and Rv1002c. Loss of protein O-mannosylation in both mutant strains was unambiguously demonstrated by efficient mass spectrometry-based glycoproteomics analysis. Unexpectedly, although the M. smegmatis phenotype was unaffected by the lack of manno-proteins, the Mtb mutant had severely impacted growth in vitro and in cellulo associated with a strong attenuation of its pathogenicity in immunocompromised mice. These data are unique in providing evidence of the biological significance of protein O-mannosylation in mycobacteria and demonstrate the crucial contribution of this protein posttranslational modification to Mtb virulence in the host.
一种类似于真菌和动物中发现的翻译后蛋白质 O-甘露糖基化过程已在主要人类病原体结核分枝杆菌（Mtb）和相关放线菌中报道。然而，这个在真核生物中至关重要的过程的作用和发生率从未在 Mtb 中得到探索。因此，我们通过失活非致病性腐生菌分枝杆菌 smegmatis 中的假定蛋白甘露糖基转移酶基因 Msmeg_5447 和 Mtb 中的 Rv1002c，分析了中断 O-甘露糖基化的影响。通过高效基于质谱的糖蛋白组学分析，明确证明了这两个突变株中蛋白质 O-甘露糖基化的缺失。出乎意料的是，尽管 M. smegmatis 表型不受缺乏甘露糖蛋白的影响，但 Mtb 突变体在体外和细胞内的生长受到严重影响，其在免疫功能低下的小鼠中的致病性明显减弱。这些数据首次提供了蛋白质 O-甘露糖基化在分枝杆菌中的生物学意义的证据，并证明了这种蛋白质翻译后修饰对 Mtb 在宿主中的毒力的至关重要的贡献。
