PapA3 is an acyltransferase required for polyacyltrehalose biosynthesis in Mycobacterium tuberculosis.
PapA3 is an acyltransferase required for polyacyltrehalose biosynthesis in Mycobacterium tuberculosis.
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DOI：
10.1074/jbc.m809088200
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发表时间：
2009-05-08
期刊：
影响因子：
--
通讯作者：
Bertozzi CR
中科院分区：
文献类型：
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作者：
Hatzios SK;Schelle MW;Holsclaw CM;Behrens CR;Botyanszki Z;Lin FL;Carlson BL;Kumar P;Leary JA;Bertozzi CR
结核分枝杆菌拥有不寻常的细胞壁，其中充满了毒力增强的脂质。致病性结核分枝杆菌特有的一种细胞壁分子是聚酰海藻糖 (PAT)，一种五酰化的、基于海藻糖的糖脂。尽管 PAT 的生物合成基因簇已被鉴定并发现与已深入研究的结核分枝杆菌细胞壁成分 sulfolipid-1 相似，但人们对 PAT 的生物合成知之甚少。在这项研究中，我们试图阐明 papA3 的功能，该基因来自编码假定的酰基转移酶的 PAT 基因座。为了确定 PapA3 是否参与 PAT 组装，我们异源表达该蛋白并评估其体外酰基转移酶活性。纯化的酶催化海藻糖与两个棕榈酰基的连续酯化，产生类似于结核分枝杆菌的2,3-二酰基海藻糖糖脂的二酰化产物。值得注意的是，PapA3 对海藻糖具有选择性。没有观察到其他结构相关的二糖的活性。结核分枝杆菌 papA3 基因的破坏导致细菌脂质提取物中 PAT 的丢失。突变菌株的补充恢复了 PAT 的产生，证明 PapA3 对于这种糖脂的体内生物合成至关重要。此外，我们确定 PAT 生物合成机制与 sulfolipid-1 的生物合成机制不存在串扰，尽管它们具有相关的结构。
Mycobacterium tuberculosis possesses an unusual cell wall that is replete with virulence-enhancing lipids. One cell wall molecule unique to pathogenic M. tuberculosis is polyacyltrehalose (PAT), a pentaacylated, trehalose-based glycolipid. Little is known about the biosynthesis of PAT, although its biosynthetic gene cluster has been identified and found to resemble that of the better studied M. tuberculosis cell wall component sulfolipid-1. In this study, we sought to elucidate the function of papA3, a gene from the PAT locus encoding a putative acyltransferase. To determine whether PapA3 participates in PAT assembly, we expressed the protein heterologously and evaluated its acyltransferase activity in vitro. The purified enzyme catalyzed the sequential esterification of trehalose with two palmitoyl groups, generating a diacylated product similar to the 2,3-diacyltrehalose glycolipids of M. tuberculosis. Notably, PapA3 was selective for trehalose; no activity was observed with other structurally related disaccharides. Disruption of the papA3 gene from M. tuberculosis resulted in the loss of PAT from bacterial lipid extracts. Complementation of the mutant strain restored PAT production, demonstrating that PapA3 is essential for the biosynthesis of this glycolipid in vivo. Furthermore, we determined that the PAT biosynthetic machinery has no cross-talk with that for sulfolipid-1 despite their related structures.