Communications Chemistry ( IF 5.9 ) Pub Date : 2020-08-07 , DOI: 10.1038/s42004-020-00356-3 Shiva K Angala 1 , Wei Li 1 , Claudia M Boot 2 , Mary Jackson 1 , Michael R McNeil 1
Mycobacterial lipoarabinomannan (LAM) is in an essential cell envelope lipopolysaccharide anchored both to the plasma and outer membranes. To understand critical biological questions such as the biosynthesis, spatial organization of LAM within the cell envelope, structural remodeling during growth, and display or lack of display of LAM-based antigenicity requires a basic understanding of the primary structure of the mannan, arabinan and how they are attached to each other. Herein, using enzymatic digestions and high-resolution mass spectrometry, we show that the arabinan component of LAM is attached at the non-reducing end of the mannan rather than to internal regions. Further, we show the presence of secondary extended mannan side chains attached to the internal mannan region. Such findings lead to a significant revision of the structure of LAM and lead to guidance of biosynthetic studies and to hypotheses of the role of LAM both in the periplasm and outside the cell as a fundamental part of the dynamic mycobacterial cell envelope.
中文翻译:
分枝杆菌脂阿拉伯甘露聚糖中阿拉伯聚糖的二级延伸甘露聚糖侧链和附着
分枝杆菌脂阿拉伯甘露聚糖 (LAM) 是一种必需的细胞包膜脂多糖,固定在质膜和外膜上。要了解关键的生物学问题,例如细胞包膜内 LAM 的生物合成、空间组织、生长过程中的结构重塑以及基于 LAM 的抗原性的显示或不显示,需要基本了解甘露聚糖、阿拉伯聚糖的一级结构以及如何他们彼此相连。在此,使用酶消化和高分辨率质谱法,我们表明 LAM 的阿拉伯聚糖成分附着在甘露聚糖的非还原端,而不是内部区域。此外,我们显示了连接到内部甘露聚糖区域的二级延伸甘露聚糖侧链的存在。