Roles of lsr2 in colony morphology and biofilm formation of Mycobacterium smegmatis
Roles of lsr2 in colony morphology and biofilm formation of Mycobacterium smegmatis
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DOI：
10.1128/jb.188.2.633-641.2006
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发表时间：
2006-01-01
影响因子：
3.2
通讯作者：
Liu, J
中科院分区：
文献类型：
--
作者：
Chen, JM;German, GJ;Liu, J
富含脂质的细胞壁是分枝杆菌属物种的定义特征。单个细胞壁组分影响不同的分枝杆菌表型，包括菌落形态、生物膜形成、抗生素抗性和毒力。在这项研究中，我们描述了一个转座子插入突变体的分枝杆菌sinegaemc（2）155，表现出改变菌落形态和缺陷的生物膜形成。该突变定位于lsr 2基因。首先被鉴定为麻风分枝杆菌的免疫显性T细胞抗原，lsr 2直向同源物已在所有测序的分枝杆菌基因组中被鉴定，并且在许多放线菌中发现同源物。虽然其确切的功能仍然未知，但定位实验表明Lsr 2是一种胞质蛋白，交联实验表明它以二聚体形式存在。细胞壁脂质成分的表征表明，M。smeglsr 2突变体缺乏两个以前未鉴定的非极性脂质。通过质谱和薄层色谱法的表征表明，这两种非极性脂质是新的含分枝菌酸酯的化合物，称为分枝菌酰-二酰基甘油（MDAGs），其中分枝菌酸（α-或α '-分枝菌酸酯）分子酯化为甘油。在与完整的lsr 2基因互补后，突变体恢复到亲本表型并且MDAG生产恢复。本研究表明，由于Lsr 2对疏水MDAGs的生物合成的影响，Lsr 2在M的殖民地形态和生物膜形成中起重要作用。恶臭
The lipid-rich cell wall is a defining feature of Mycobacterium species. Individual cell wall components affect diverse mycobacterial phenotypes including colony morphology, biofilm formation, antibiotic resistance, and virulence. In this study, we describe a transposon insertion mutant of Mycobacterium sinegmatis mc(2)155 that exhibits altered colony morphology and defects in biofilm formation. The mutation was localized to the lsr2 gene. First identified as an immunodominant T-cell antigen of Mycobacterium leprae, lsr2 orthologs have been identified in all sequenced mycobacterial genomes, and homologs are found in many actinomycetes. Although its precise function remains unknown, localization experiments indicate that Lsr2 is a cytosolic protein, and cross-linking experiments demonstrate that it exists as a dimer. Characterization of cell wall lipid components reveals that the M. smegmatis lsr2 mutant lacks two previously unidentified apolar lipids. Characterization by mass spectrometry and thin-layer chromatography indicate that these two apolar lipids are novel mycolate-containing compounds, called mycolyl-diacylglycerols (MDAGs), in which a mycolic acid (alpha- or alpha'-mycolate) molecule is esterified to a glycerol. Upon complementation with an intact lsr2 gene, the mutant reverts to the parental phenotypes and MDAG production is restored. This study demonstrates that due to its impact on the biosynthesis of the hydrophobic MDAGs, Lsr2 plays an important role in the colony morphology and biofilm formation of M. smegmatis.