The N-Acetylmuramic Acid 6-Phosphate Phosphatase MupP Completes the Pseudomonas Peptidoglycan Recycling Pathway Leading to Intrinsic Fosfomycin Resistance.
The N-Acetylmuramic Acid 6-Phosphate Phosphatase MupP Completes the Pseudomonas Peptidoglycan Recycling Pathway Leading to Intrinsic Fosfomycin Resistance.
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DOI：
10.1128/mbio.00092-17
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发表时间：
2017-03-28
期刊：
影响因子：
6.4
通讯作者：
Mayer C
中科院分区：
文献类型：
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作者：
Borisova M;Gisin J;Mayer C
细菌细胞被包裹在网状肽聚糖（PGN）细胞壁中并由其稳定，该细胞壁在细菌生长期间经历周转。PGN周转片段经常通过称为PGN再循环的途径被细胞回收。细胞壁糖N-乙酰胞壁酸（MurNAc）的回收利用有两种不同的途径。在大肠杆菌和相关肠细菌以及大多数革兰氏阳性菌中，MurNAc通过需要MurNAc 6-磷酸醚酶（大肠杆菌中的MurQ）的分解代谢途径回收。然而，许多革兰氏阴性细菌，包括假单胞菌属，缺乏MurQ直系同源物，并使用替代的合成代谢再循环途径，绕过尿苷二磷酸（UDP）-MurNAc（PGN的第一个定向前体）的从头生物合成。具有后一种途径的细菌对抗生素磷霉素具有内在抗性，磷霉素靶向UDP-MurNAc的从头生物合成。我们在这里报告的识别和表征的磷酸酶，命名为MupP，已被预测完成合成代谢循环途径的假单胞菌属物种，但迄今为止仍然未知。它属于磷酸酶的大卤酸脱卤酶家族，并特异性地将MurNAc 6-磷酸转化为MurNAc。恶臭假单胞菌的ΔmupP突变体对磷霉素高度敏感，积累了大量的MurNAc 6-磷酸，并且显示出比野生型细胞更低的UDP-MurNAc水平，这与MupP在合成代谢PGN再循环途径中的作用以及作为磷霉素内在抗性的决定因素完全一致。许多革兰氏阴性细菌，但不是大肠杆菌，利用细胞壁补救途径，有助于UDP-MurNAc的池，UDP-MurNAc是细菌中细胞壁合成的第一个定向前体。这种补救途径特别令人感兴趣，因为它赋予对抗生素磷霉素的内在抗性，磷霉素阻断从头UDP-MurNAc生物合成。在这里，我们确定并表征了补救途径中先前缺失的酶，恶臭假单胞菌的MurNAc 6-磷酸磷酸酶MupP。MupP与合成代谢再循环途径的其他酶AnmK、AmgK和MurU一起产生UDP-MurNAc，使细菌对磷霉素具有内在抗性，因此可以作为抗微生物治疗的新型药物靶标。
Bacterial cells are encased in and stabilized by a netlike peptidoglycan (PGN) cell wall that undergoes turnover during bacterial growth. PGN turnover fragments are frequently salvaged by the cells via a pathway referred to as PGN recycling. Two different routes for the recycling of the cell wall sugar N-acetylmuramic acid (MurNAc) have been recognized in bacteria. In Escherichia coli and related enterobacteria, as well as in most Gram-positive bacteria, MurNAc is recovered via a catabolic route requiring a MurNAc 6-phosphate etherase (MurQ in E. coli) enzyme. However, many Gram-negative bacteria, including Pseudomonas species, lack a MurQ ortholog and use an alternative, anabolic recycling route that bypasses the de novo biosynthesis of uridyldiphosphate (UDP)-MurNAc, the first committed precursor of PGN. Bacteria featuring the latter pathway become intrinsically resistant to the antibiotic fosfomycin, which targets the de novo biosynthesis of UDP-MurNAc. We report here the identification and characterization of a phosphatase enzyme, named MupP, that had been predicted to complete the anabolic recycling pathway of Pseudomonas species but has remained unknown so far. It belongs to the large haloacid dehalogenase family of phosphatases and specifically converts MurNAc 6-phosphate to MurNAc. A ΔmupP mutant of Pseudomonas putida was highly susceptible to fosfomycin, accumulated large amounts of MurNAc 6-phosphate, and showed lower levels of UDP-MurNAc than wild-type cells, altogether consistent with a role for MupP in the anabolic PGN recycling route and as a determinant of intrinsic resistance to fosfomycin. Many Gram-negative bacteria, but not E. coli, make use of a cell wall salvage pathway that contributes to the pool of UDP-MurNAc, the first committed precursor of cell wall synthesis in bacteria. This salvage pathway is of particular interest because it confers intrinsic resistance to the antibiotic fosfomycin, which blocks de novo UDP-MurNAc biosynthesis. Here we identified and characterized a previously missing enzyme within the salvage pathway, the MurNAc 6-phosphate phosphatase MupP of P. putida. MupP, together with the other enzymes of the anabolic recycling pathway, AnmK, AmgK, and MurU, yields UDP-MurNAc, renders bacteria intrinsically resistant to fosfomycin, and thus may serve as a novel drug target for antimicrobial therapy.