Lipoarabinomannan Localization and Abundance during Growth of Mycobacterium smegmatis
Lipoarabinomannan Localization and Abundance during Growth of Mycobacterium smegmatis
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DOI：
10.1128/jb.05299-11
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发表时间：
2011-10-01
影响因子：
3.2
通讯作者：
Crick, Dean C.
中科院分区：
文献类型：
--
作者：
Dhiman, Rakesh K.;Dinadayala, Premkumar;Crick, Dean C.
脂肪阿拉伯甘露聚糖(LAM)是一种存在于分枝杆菌中的结构不均一的两亲性脂多糖。和其他放线菌，它构成细胞壁的主要成分，并显示出广泛的免疫调节作用。对耻垢分枝杆菌亚细胞组分和球体的分析表明，LAM和脂甘露聚糖(LM)主要存在于细胞壁丰富的亚细胞组分中，并与球体制剂中是否含有霉菌酸有关，这表明LAM和LM主要与分枝杆菌的外膜有关。在这些研究过程中，细胞壁的LAM/LM含量随培养年限的变化而显着变化。污垢分枝杆菌细胞壁的LAM含量随着细菌接近稳定期而显著减少，而LM、霉菌酸和阿拉伯半乳糖的含量似乎没有变化。此外，细胞形态和抗酸染色特性随细菌生长阶段的不同而不同。在对数生长期，该菌为典型的杆状抗酸杆菌，而在稳定期，污垢分枝杆菌失去了特征的杆状，并形成了碳品红的点状抗酸染色模式。活菌数与LAM含量和表型无关。综上所述，这些结果表明，LAM主要定位于细胞壁中的真菌酸，而且耻垢分枝杆菌中LAM的细胞浓度受生长阶段的选择性调节。
Lipoarabinomannan (LAM) is a structurally heterogeneous amphipathic lipoglycan present in Mycobacterium spp. and other actinomycetes, which constitutes a major component of the cell wall and exhibits a wide spectrum of immunomodulatory effects. Analysis of Mycobacterium smegmatis subcellular fractions and spheroplasts showed that LAM and lipomannan (LM) were primarily found in a cell wall-enriched subcellular fraction and correlated with the presence (or absence) of the mycolic acids in spheroplast preparations, suggesting that LAM and LM are primarily associated with the putative outer membrane of mycobacteria. During the course of these studies significant changes in the LAM/LM content of the cell wall were noted relative to the age of the culture. The LAM content of the M. smegmatis cell wall was dramatically reduced as the bacilli approached stationary phase, whereas LM, mycolic acid, and arabinogalactan content appeared to be unchanged. In addition, cell morphology and acid-fast staining characteristics showed variations with growth phase of the bacteria. In the logarithmic phase, the bacteria were found to be classic rod-shaped acid-fast bacilli, while in the stationary phase M. smegmatis lost the characteristic rod shape and developed a punctate acid-fast staining pattern with carbolfuchsin. The number of viable bacteria was independent of LAM content and phenotype. Taken together, the results presented here suggest that LAM is primarily localized with the mycolic acids in the cell wall and that the cellular concentration of LAM in M. smegmatis is selectively modulated with the growth phase.