Disruption of msl3 abolishes the synthesis of mycolipanoic and mycolipenic acids required for polyacyltrehalose synthesis in Mycobacterium tuberculosis H37Rv and causes cell aggregation
Disruption of msl3 abolishes the synthesis of mycolipanoic and mycolipenic acids required for polyacyltrehalose synthesis in Mycobacterium tuberculosis H37Rv and causes cell aggregation
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DOI：
10.1046/j.1365-2958.2002.03119.x
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发表时间：
2002-09-01
影响因子：
3.6
通讯作者：
Kolattukudy, PE
中科院分区：
文献类型：
--
作者：
Dubey, VS;Sirakova, TD;Kolattukudy, PE
含有多个甲基支链脂肪酸的结核分枝杆菌细胞壁脂在致病机制中起着重要作用，从而为新的抗分枝杆菌药物提供靶点。分枝杆菌酸合成酶基因(Mas)编码一种产生一类此类酸的酶。在基因组中鉴定出7个MAS样基因(MS1、S)。其中一个，ms13，最初被注释为两个独立的基因，PKS 3和PKS 4，现在被证明构成了一个单一的开放阅读框架，编码一个220.3 kDa的蛋白质。利用噬菌体介导的递送系统对MSL3进行干扰，并通过对引入的破坏基因侧翼区的聚合酶链式反应分析和Southern分析证实了突变体中的基因替换。生化分析表明，msl 3突变体不产生聚酰基海藻糖的主要成分菌烯酸和菌烯(邻)酸，因此缺乏这种细胞壁脂，但合成了所有其他类型的脂类。缺乏锚定表面暴露的酰基海藻糖的主要酰基链导致了一种新的生长形态；细胞相互粘连，很可能是通过暴露的疏水细胞表面之间的细胞间相互作用，表现出珠状生长形态，而不影响整体生长速度。
Cell wall lipids of Mycobacterium tuberculosis containing multiple methyl branched fatty acids play critical roles in pathogenesis and thus offer targets for new antimycobacterial drugs. Mycocerosicacid synthase gene (mas) encodes the enzyme that produces one class of such acids. Seven mas -like genes (msl s) were identified in the genome. One of them, msl 3, originally annotated as two separate genes, pks 3 and pks 4, is now shown to constitute a single open reading frame, which encodes a 220.3 kDa protein. Msl 3 was disrupted using a phage mediated delivery system and the gene replacement in the mutant was confirmed by polymerase chain reaction analysis of the flanking regions of the introduced disrupted gene and by Southern analysis. Biochemical analysis showed that the msl 3 mutant does not produce mycolipenoic acids and mycolipenic(phthienoic) acids, the major constituents of polyacyl trehaloses and thus lacks this cell wall lipid, but synthesizes all of the other classes of lipids. The absence of the major acyl chains that anchor the surface-exposed acyltrehaloses causes a novel growth morphology; the cells stick to each other, most probably via the intercellular interaction between the exposed hydrophobic cell surfaces, manifesting a bead-like growth morphology without affecting the overall growth rate.