Unique structural features of the peptidoglycan of Mycobacterium leprae
Unique structural features of the peptidoglycan of Mycobacterium leprae
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DOI：
10.1128/jb.00982-07
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发表时间：
2008-01-01
影响因子：
3.2
通讯作者：
Brennan, Patrick J.
中科院分区：
文献类型：
--
作者：
Mahapatra, Sebabrata;Crick, Dean C.;Brennan, Patrick J.
分枝杆菌属的肽聚糖结构。主要用易于培养的耻垢分枝杆菌和结核分枝杆菌进行了研究，并已证明其具有不寻常的特征，包括除了 N-乙酰化之外，还出现 N-乙醇基化、胞壁酸残基以及内消旋二氨基庚二酸残基之间的直接交联。根据早期研究的结果，来自体内的不可培养的麻风分枝杆菌的肽聚糖被认为具有来自其他分枝杆菌的肽聚糖的基本结构特征，除了报道的肽侧链中的L-丙氨酸被甘氨酸取代之外。在本研究中，我们通过液相色谱和质谱联用详细分析了麻风分枝杆菌肽聚糖的结构。与早期报道相反，以及结核分枝杆菌和耻垢分枝杆菌中的肽聚糖，麻风分枝杆菌肽聚糖的胞壁酸残基完全被N乙酰化。麻风分枝杆菌的非交联肽侧链由四肽和三肽组成，其中一些含有额外的甘氨酸残基。基于这些发现和基因组比较，可以得出结论，麻风分枝杆菌中的大规模基因组衰退并没有显着影响肽聚糖生物合成途径，除了负责 N-乙醇酰胞壁酸生物合成的非功能性 namH 基因之外。
The peptidoglycan structure of Mycobacterium spp. has been investigated primarily with the readily cultivable Mycobacterium smegmatis and Mycobacterium tuberculosis and has been shown to contain unusual features, including the occurrence of N-glycolylated, in addition to N-acetylated, muramic acid residues and direct cross-linkage between meso-diaminopimelic acid residues. Based on results from earlier studies, peptidoglycan from in vivo-derived noncultivable Mycobacterium leprae was assumed to possess the basic structural features of peptidoglycans from other mycobacteria, other than the reported replacement of L-alanine by glycine in the peptide side chains. In the present study, we have analyzed the structure of M. leprae peptidoglycan in detail by combined liquid chromatography and mass spectrometry. In contrast to earlier reports, and to the peptidoglycans in M. tuberculosis and M. smegmatis, the muramic acid residues of M. leprae peptidoglycan are exclusively N acetylated. The un-cross-linked peptide side chains of M. leprae consist of tetra- and tripeptides, some of which contain additional glycine residues. Based on these findings and genome comparisons, it can be concluded that the massive genome decay in M. leprae does not markedly affect the peptidoglycan biosynthesis pathway, with the exception of the nonfunctional namH gene responsible for N-glycolylmuramic acid biosynthesis.