Ppm1, a novel polyprenol monophosphomannose synthase from Mycobacterium tuberculosis
Ppm1, a novel polyprenol monophosphomannose synthase from Mycobacterium tuberculosis
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DOI：
10.1042/bj20020107
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发表时间：
2002-07-15
影响因子：
4.1
通讯作者：
Besra, GS
中科院分区：
文献类型：
--
作者：
Gurcha, SS;Baulard, AR;Besra, GS
多萜醇单磷酸甘露糖（Dolichol monophosphomannose，DPO）是甘露糖（Manose，Man）的一种供体，参与了多种真核生物糖基化过程。有趣的是，相关的聚戊烯醇单磷酸甘露糖（PPM）参与脂甘露聚糖和脂阿拉伯甘露聚糖的生物合成，脂甘露聚糖和脂阿拉伯甘露聚糖是在分枝杆菌中发现的称为调制蛋白的关键细菌因子。基于与已知的PPM合酶的相似性，我们已经鉴定并表征了结核分枝杆菌的PPM合酶，现在称为Mt-Ppm 1。在本研究中，我们证明，Mt-PPM 1具有一个不寻常的两个结构域的架构，其中第二个结构域是足够的PPM合成。然而，当在分枝杆菌中单独过表达时，Mt-Ppm 1的结构域1似乎增加PPM的合成。有趣的是，其他分枝杆菌如M. smegalgae，M. avium和M.麻风产生两种不同的蛋白质，它们与Mt-Ppm 1中发现的两个结构域相似。使用体外试验，我们还表明，Mt-Ppm 1转移人从GDP-人的脂质单磷酸受体的结构多样的范围。PPM合酶作为脂阿拉伯甘露聚糖生物合成中的关键酶的鉴定现在为基因破坏以产生用于随后的免疫学研究的突变体提供了有吸引力的候选物。PPM合成酶也可以作为特异性M抑制剂的靶点。结核
Dolichol monophosphomannose (DPM) is an ever-present donor of mannose (Man) in various eukaryotic glycosylation processes. Intriguingly, the related polyprenol monophosphomannose (PPM) is involved in the biosynthesis of lipomannan and lipoarabinomanan, key bacterial factors termed modulins that are found in mycobacteria. Based on similarities to known DPM synthases, we have identified and characterized the PPM synthase of Mycobacterium tuberculosis, now termed Mt-Ppm1. In the present study, we demonstrate that Mt-Ppm1 possesses an unusual two-domain architecture, by which the second domain is sufficient for PPM synthesis. However, when overexpressed separately in mycobacteria, domain 1 of Mt-Ppm1 appears to increase the synthesis of PPM. Interestingly, other mycobacteria such as M. smegmatis, M. avium and M. leprae produce two distinct proteins, which are similar to the two domains found in Mt-Ppm1. Using an in vitro assay, we also demonstrate that Mt-Ppm1 transfers Man from GDP-Man to a structurally diverse range of lipid monophosphate acceptors. The identification of the PPM synthase as a key enzyme in lipoarabinomannan biosynthesis now provides an attractive candidate for gene disruption to generate mutants for subsequent immunological studies. PPM synthase can also be exploited as a target for specific inhibitors of M. tuberculosis.