Three-dimensional structure of the bacterial cell wall peptidoglycan
Three-dimensional structure of the bacterial cell wall peptidoglycan
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DOI：
10.1073/pnas.0510182103
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发表时间：
2006-03-21
影响因子：
11.1
通讯作者：
Mobashery, S
中科院分区：
文献类型：
--
作者：
Meroueh, SO;Bencze, KZ;Mobashery, S
细菌肽聚糖是细胞壁的主要组成部分，其三维结构是生物化学中最重要但尚未解决的结构问题之一。肽聚糖包括交替的N-乙酰葡糖胺（NAG）和N-乙酰胞壁二糖（NAM），后者具有肽茎。相邻的肽茎通过细胞壁生物合成的转肽酶交联，以提供具有细菌所需的结构完整性的细胞壁聚合物。细胞壁及其生物合成酶是抗生素的靶标。由于其复杂性和缺乏纯样品，细胞壁的3D结构一直难以捉摸。在此，我们报告了通过NMR测定的细胞壁的2-kDa NAG-NAM（五肽）-NAG-NAM（五肽）合成片段的3D溶液结构。该肽聚糖的聚糖骨架形成右旋螺旋，NAG-NAM重复的周期为3（螺旋的每圈）。五肽的前两个氨基酸采用有限数量的构象。基于这种结构，提出了一种细菌细胞壁的模型。
The 3D structure of the bacterial peptidoglycan, the major constituent of the cell wall, is one of the most important, yet still unsolved, structural problems in biochemistry. The peptidoglycan comprises alternating N-acetylglucosamine (NAG) and N-acetylmuramic disaccharide (NAM) saccharides, the latter of which has a peptide stem. Adjacent peptide stems are cross-linked by the transpeptidase enzymes of cell wall biosynthesis to provide the cell wall polymer with the structural integrity required by the bacterium. The cell wall and its biosynthetic enzymes are targets of antibiotics. The 3D structure of the cell wall has been elusive because of its complexity and the lack of pure samples. Herein we report the 3D solution structure as determined by NMR of the 2-kDa NAG-NAM(pentapeptide)-NAG-NAM(pentapeptide) synthetic fragment of the cell wall. The glycan backbone of this peptidoglycan forms a right-handed helix with a periodicity of three for the NAG-NAM repeat (per turn of the helix). The first two amino acids of the pentapeptide adopt a limited number of conformations. Based on this structure a model for the bacterial cell wall is proposed.