Clostridium difficile Has an Original Peptidoglycan Structure with a High Level of N-Acetylglucosamine Deacetylation and Mainly 3-3 Cross-links
Clostridium difficile Has an Original Peptidoglycan Structure with a High Level of N-Acetylglucosamine Deacetylation and Mainly 3-3 Cross-links
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DOI：
10.1074/jbc.m111.259150
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发表时间：
2011-08-19
影响因子：
4.8
通讯作者：
Pons, Jean-Louis
中科院分区：
文献类型：
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作者：
Peltier, Johann;Courtin, Pascal;Pons, Jean-Louis
艰难梭菌的营养细胞壁肽聚糖的结构，通过分析其组成的muropeptides与相结合的反相高压液相色谱分离muropeptides，氨基酸分析，质谱和串联质谱。36个胞肽的结构证明了C.艰难梭菌营养细胞肽聚糖。首先，其特征在于显著高水平的N-乙酰葡糖胺脱乙酰化。此外，大多数二聚体（约75%）包含A（2）pm（3）-> A（2）pm（3）（A（2）pm，2，6-二氨基庚二酸）交联，并且仅少数更经典的Ala（4）-> A（2）pm（3）交联。此外，大量的胞肽含有以Gly而不是D-Ala结尾的修饰的四肽茎（4）。两个L，D-转肽酶同源基因存在于C.艰难梭菌630，命名为LDT（CD 1）和LDT（CD 2），被灭活。ldt（cd 1）或ldt（cd 2）的失活显著降低了3-3交联的丰度，导致肽聚糖网状结构的显著减少，并证明ldt（cd 1）和ldt（cd 2）编码的蛋白质具有冗余的L，D-转肽酶活性。在氨苄青霉素存在下，3-3交联对肽聚糖合成的贡献增加，表明该药物不抑制C.很难
The structure of the vegetative cell wall peptidoglycan of Clostridium difficile was determined by analysis of its constituent muropeptides with a combination of reverse-phase high pressure liquid chromatography separation of muropeptides, amino acid analysis, mass spectrometry and tandem mass spectrometry. The structures assigned to 36 muropeptides evidenced several original features in C. difficile vegetative cell peptidoglycan. First, it is characterized by a strikingly high level of N-acetylglucosamine deacetylation. In addition, the majority of dimers (around 75%) contains A(2)pm(3) -> A(2)pm(3) (A(2)pm, 2,6-diaminopimelic acid) cross-links and only a minority of the more classical Ala(4) -> A(2)pm(3) cross-links. Moreover, a significant amount of muropeptides contains a modified tetrapeptide stem ending in Gly instead of D-Ala(4). Two L,D-transpeptidases homologues encoding genes present in the genome of C. difficile 630 and named ldt(cd1) and ldt(cd2), were inactivated. The inactivation of either ldt(cd1) or ldt(cd2) significantly decreased the abundance of 3-3 cross-links, leading to a marked decrease of peptidoglycan reticulation and demonstrating that both ldt(cd1)-and ldt(cd2)-encoded proteins have a redundant L, D-transpeptidase activity. The contribution of 3-3 cross-links to peptidoglycan synthesis increased in the presence of ampicillin, indicating that this drug does not inhibit the L,D-transpeptidation pathway in C. difficile.