Efficient Preparation of UDP-MurNAc-pentapeptide and Lipid I as Peptidoglycan Precursors
Date Issued
2006
Date
2006
Author(s)
Hsu, Fu-Hsian
DOI
en-US
Abstract
UDP-MurNAc-pentapeptide和Lipid I是peptidoglycan生合成的重要的中間物, UDP-MurNAc-pentapeptide的生合成主要是發生在細菌的細胞質內,分別由六個酵素參予反應。 UDP-MurNAc-pentapeptide是酵素MraY的受質,它的功能是將muramyl -pentapeptide接到位在細胞膜上55個碳的undecaprenyl phosphate上面; 也就是所謂的Lipid I。之後MurG 再將一個GlcNAc接到 muramyl基團的羥基上面形成所謂的Lipid II。Lipid II之後再翻轉至細胞膜外側被另外兩個酵素行聚合以及交叉結合的動作,形成peptidoglycan。
為了發展新一代的抗生素,我們建立了一套有效率的方式去得到UMP以及Lipid I。UMP純化來自於一株Gram-negative的菌,稱為Bacillus cereus T, 我們利用過去已知的步驟再經過部分的修飾之後來純化UMP. 並且在UMP上面加上了了一個螢光基團,如FITC和dansyl。另外利用酵素和化學的方式去研究將UDP-MurNAc-pentapeptide和脂肪鍊接在一起,合成Lipid和它的類似物。
UDP-MurNAc-pentapeptide (UMP) and Lipid I are the key intermediates for peptidoglycan biosynthesis. The biosynthesis of UDP-MurNAc-pentapeptide takes place in the cytoplasm, where six enzymes are involved. An undecaprenyl chain is then attached to the muramyl pentapeptide to give Lipid I. Additional glycosylation of GlcNAc to the C4-OH of muramyl group produces Lipid II that is subjected to further sugar chain polymerization and peptide chain cross-linked to form peptidoglycans.
In order for development of new antibiotics, we aim to establish efficient preparation of UMP and Lipid I. UMP was purified from Bacillus cereus T on the basis of a modified procedure and labeled with a fluorescence group (such a FITC and dansyl group). Chemical and enzymatic methods were then studied to incorporate a long lipid chain for preparation of Lipid I and its analogues.
Subjects
細胞壁
抗藥性
cell wall
antibiotics resistance
Type
other