An Alternative Route for Recycling of N-Acetylglucosamine from Peptidoglycan Involves the N-Acetylglucosamine Phosphotransferase System in Escherichia coli
An Alternative Route for Recycling of N-Acetylglucosamine from Peptidoglycan Involves the N-Acetylglucosamine Phosphotransferase System in Escherichia coli
复制标题
DOI：
10.1128/jb.00448-09
复制
发表时间：
2009-09-15
影响因子：
3.2
通讯作者：
Plumbridge, Jacqueline
中科院分区：
文献类型：
--
作者：
Plumbridge, Jacqueline
此前已在大肠杆菌中鉴定出一组专门用于回收肽聚糖的氨基糖成分的酶。该完整途径包括N-乙酰氨基葡萄糖(GlcNAc)分解代谢途径的NAGA编码的酶，N-乙酰氨基葡萄糖-6-磷酸脱乙酰酶(GlcNAc6P)。NAGA的突变可能通过阻止肽聚糖的循环，导致GlcNAc6P的毫摩尔浓度积累。在专门的循环途径中，编码NAGA上游关键酶的基因突变(AMPG、NagZ、NagK、MurQ和anmK)预计会中断循环过程，减少但不能消除GlcNAc6P的积累。研究发现，GlcNAc磷酸转移酶系统(PTS)的NAGE基因突变可使在NAGA菌株中积累的GlcNAc6P的数量减少50%，并与专用循环途径的突变一起，消除所有GlcNAc6P的积累。这表明，编码NAG的PTS转运蛋白对肽聚糖的回收有重要贡献。ManXYZ编码的PTS转运蛋白在细胞质GlcNAc6P的形成中起着很小的作用，但在从细胞质中分泌GlcNAc和/或GlcNAc6P方面似乎起到了更重要的作用。
A set of enzymes dedicated to recycling of the amino sugar components of peptidoglycan has previously been identified in Escherichia coli. The complete pathway includes the nagA-encoded enzyme, N-acetylglucosamine-6-phosphate (GlcNAc6P) deacetylase, of the catabolic pathway for use of N-acetylglucosamine (GlcNAc). Mutations in nagA result in accumulation of millimolar concentrations of GlcNAc6P, presumably by preventing peptidoglycan recycling. Mutations in the genes encoding the key enzymes upstream of nagA in the dedicated recycling pathway (ampG, nagZ, nagK, murQ, and anmK), which were expected to interrupt the recycling process, reduced but did not eliminate accumulation of GlcNAc6P. A mutation in the nagE gene of the GlcNAc phosphotransferase system (PTS) was found to reduce by 50% the amount of GlcNAc6P which accumulated in a nagA strain and, together with mutations in the dedicated recycling pathway, eliminated all the GlcNAc6P accumulation. This shows that the nagE-encoded PTS transporter makes an important contribution to the recycling of peptidoglycan. The manXYZ-encoded PTS transporter makes a minor contribution to the formation of cytoplasmic GlcNAc6P but appears to have a more important role in secretion of GlcNAc and/or GlcNAc6P from the cytoplasm.