Labarre Cécile, Dautin Nathalie, Grzegorzewicz Anna, Jackson Mary, McNeil Michael, Mohiman Niloofar, Sago Laila, Bayan Nicolas
Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette cedex, France.
Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91198, Gif-sur-Yvette cedex, France; Laboratoire de Biologie Physico-Chimique des Protéines Membranaires, Université de Paris, LBPC-PM, CNRS, UMR7099, 75005, Paris, France.
Res Microbiol. 2021 Nov-Dec;172(7-8):103874. doi: 10.1016/j.resmic.2021.103874. Epub 2021 Sep 4.
LppX is an important virulence factor essential for surface localization of phthiocerol dimycocerosates (DIM) in Mycobacterium tuberculosis. Based on Concanavalin A recognition, M. tuberculosis LppX (LppX-tb) was initially proposed to be glycosylated in M. tuberculosis and more recently this glycosylation was characterized by mass spectrometry analysis on LppX-tb expressed and purified from Corynebacterium glutamicum. Here, using this model organism and Mycobacterium smegmatis, we show that S16 and T18 residues of LppX-tb are indeed glycosylated with several hexoses units. Interestingly this glycosylation is strictly dependent on the mannosyl transferase PMT which, in M. tuberculosis, has been reported to be crucial for virulence. Using a site directed mutagenesis approach, we were able to show that the absence of S16 and T18 glycosylation does not alter phthiocerol dimycocerosates (DIM) localization in M. tuberculosis.
脂阿拉伯甘露聚糖外膜蛋白X（LppX）是结核分枝杆菌中结核菌醇二霉菌酸酯（DIM）定位于细胞表面所必需的一种重要毒力因子。基于伴刀豆球蛋白A识别，结核分枝杆菌LppX（LppX-tb）最初被认为在结核分枝杆菌中发生了糖基化，最近通过对从谷氨酸棒杆菌表达和纯化的LppX-tb进行质谱分析对这种糖基化进行了表征。在此，利用这种模式生物和耻垢分枝杆菌，我们表明LppX-tb的S16和T18残基确实被多个己糖单位糖基化。有趣的是，这种糖基化严格依赖于甘露糖基转移酶PMT，在结核分枝杆菌中，据报道该酶对毒力至关重要。使用定点诱变方法，我们能够证明S16和T18糖基化的缺失不会改变结核分枝杆菌中结核菌醇二霉菌酸酯（DIM）的定位。
