Aguilera-Correa John Jairo, Wei Fangyu, Leclercq Louis-David, Tasrini Yara, Mullapudi Edukondalu, Daher Wassim, Nakajima Kazuki, Canaan Stéphane, Herrmann Jean-Louis, Wilmanns Matthias, Guérardel Yann, Wen Liuqing, Kremer Laurent
Centre National de la Recherche Scientifique UMR 9004, Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, Montpellier, France.
Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China.
J Biol Chem. 2024 Nov;300(11):107852. doi: 10.1016/j.jbc.2024.107852. Epub 2024 Oct 1.
Mycobacterium abscessus causes severe lung infections in cystic fibrosis patients and exhibits smooth (S) or rough (R) morphotypes. Disruption of glycopeptidolipid (GPL) production results in the S-to-R transition but the underlying molecular mechanisms of this transition remain incompletely understood. Herein, we characterized MAB_4111c in relation to GPL synthesis and investigated the effects of MAB_4111c deletion in M. abscessus pathogenicity. An enzymatic assay indicated that MAB_4111c, also designated Tle for Talose epimerase, is converting dTDP-L-Rhamnose into dTDP-6-deoxy-L-Talose. A tle deletion mutant was constructed in the S variant of M. abscessus and relative areas of Rhamnose and 6-deoxy-Talose and their methylated forms expressed as ratios of total monosaccharides, showed an altered GPL profile lacking 6-deoxy-Talose. Thus, Tle provides dTDP-6-deoxy-L-Talose, subsequently used by the glycosyltransferase Gtf1 to transfer 6-deoxy-Talose to the GPL backbone. Strikingly, the tle mutant exhibited an R morphotype, showed impaired sliding motility and biofilm formation, and these phenotypes were rescued upon functional complementation. Moreover, deletion of tle in M. abscessus results in increased pathogenicity and killing in zebrafish embryos. Together, our results underscore the importance of the dTDP-L-Rhamnose 4-epimerase activity in GPL biosynthesis and in influencing M. abscessus virulence.
脓肿分枝杆菌可导致囊性纤维化患者发生严重肺部感染，并呈现光滑（S）或粗糙（R）两种形态型。糖肽脂（GPL）产生的破坏会导致从S型向R型的转变，但这种转变的潜在分子机制仍未完全了解。在此，我们对与GPL合成相关的MAB_4111c进行了表征，并研究了MAB_4111c缺失对脓肿分枝杆菌致病性的影响。酶活性测定表明，MAB_4111c也被称为塔罗糖差向异构酶（Tle），可将dTDP-L-鼠李糖转化为dTDP-6-脱氧-L-塔罗糖。在脓肿分枝杆菌的S变体中构建了一个tle缺失突变体，鼠李糖和6-脱氧塔罗糖及其甲基化形式的相对面积以总单糖的比例表示，显示出缺乏6-脱氧塔罗糖的GPL谱改变。因此，Tle提供dTDP-6-脱氧-L-塔罗糖，随后糖基转移酶Gtf1将6-脱氧塔罗糖转移到GPL主链上。引人注目的是，tle突变体呈现R形态型，滑动运动性和生物膜形成受损，并且这些表型在功能互补后得以挽救。此外，脓肿分枝杆菌中tle的缺失导致斑马鱼胚胎中的致病性增加和杀伤作用增强。总之，我们的结果强调了dTDP-L-鼠李糖4-差向异构酶活性在GPL生物合成和影响脓肿分枝杆菌毒力方面的重要性。
