CNC-Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra, Portugal.
Sci Rep. 2011;1:177. doi: 10.1038/srep00177. Epub 2011 Nov 30.
Mycobacteria synthesize intracellular methylglucose lipopolysaccharides (MGLP) proposed to regulate fatty acid synthesis. Although their structures have been elucidated, the identity of most biosynthetic genes remains unknown. The first step in MGLP biosynthesis is catalyzed by a glucosyl-3-phosphoglycerate synthase (GpgS, Rv1208 in Mycobacterium tuberculosis H37Rv). However, a typical glucosyl-3-phosphoglycerate phosphatase (GpgP, EC3.1.3.70) for dephosphorylation of glucosyl-3-phosphoglycerate to glucosylglycerate, was absent from mycobacterial genomes. We purified the native GpgP from Mycobacterium vanbaalenii and identified the corresponding gene deduced from amino acid sequences by mass spectrometry. The M. tuberculosis ortholog (Rv2419c), annotated as a putative phosphoglycerate mutase (PGM, EC5.4.2.1), was expressed and functionally characterized as a new GpgP. Regardless of the high specificity for glucosyl-3-phosphoglycerate, the mycobacterial GpgP is not a sequence homolog of known isofunctional GpgPs. The assignment of a new function in M. tuberculosis genome expands our understanding of this organism's genetic repertoire and of the early events in MGLP biosynthesis.
分枝杆菌合成细胞内甲基葡萄糖脂多糖（MGLP），据推测其可以调节脂肪酸的合成。尽管它们的结构已经阐明，但大多数生物合成基因的身份仍然未知。MGLP 生物合成的第一步是由葡萄糖基-3-磷酸甘油酸合酶（GpgS，结核分枝杆菌 H37Rv 中的 Rv1208）催化。然而，用于将葡萄糖基-3-磷酸甘油酸去磷酸化为葡萄糖基甘油酸的典型葡萄糖基-3-磷酸甘油酸磷酸酶（GpgP，EC3.1.3.70）在分枝杆菌基因组中缺失。我们从分枝杆菌属 vanbaalenii 中纯化了天然 GpgP，并通过质谱鉴定了相应的基因。从氨基酸序列推断出结核分枝杆菌的同源物（Rv2419c）被注释为一个假定的磷酸甘油酸变位酶（PGM，EC5.4.2.1），并被表达和功能表征为一种新的 GpgP。尽管对葡萄糖基-3-磷酸甘油酸具有高度特异性，但分枝杆菌的 GpgP 不是已知同工型 GpgP 的序列同源物。在结核分枝杆菌基因组中赋予新的功能扩展了我们对该生物体遗传基因库的理解，以及对 MGLP 生物合成早期事件的理解。
