Functional analysis of D-alanylation of lipoteichoic acid in the probiotic strain Lactobacillus rhamnosus GG
Functional analysis of D-alanylation of lipoteichoic acid in the probiotic strain Lactobacillus rhamnosus GG
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DOI：
10.1128/aem.02083-06
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发表时间：
2007-06-01
影响因子：
4.4
通讯作者：
De Keersmaecker, Sigrid C. J.
中科院分区：
文献类型：
--
作者：
Velez, Monica Perea;Verhoeven, Tine L. A.;De Keersmaecker, Sigrid C. J.
脂壁酸（LTA）是一种大型两亲分子，在革兰氏阳性细菌中具有多种功能，如维持细胞壁稳态。LTA的d -丙烯酰化需要dlt操纵子编码的蛋白质，这一过程与该聚合物的电荷特性直接相关，这对其功能有很大影响。核磁共振分析证实，鼠李糖乳杆菌GG （ATCC 53103）的dltD插入失活导致LTA中d -丙烯酰酯完全缺失。这反映在细菌细胞表面特性的改变上。与野生型相比，dltD菌株的细胞长度增加了2.4倍，对胃液挑战的生存能力较低，对人β -防御素-2的敏感性增加，自溶率增加，在阴离子清洁剂存在下启动生长的能力增加，而在阳离子肽存在下启动生长的能力下降。然而，体外实验显示，在粘附人肠上皮细胞、生物膜形成和免疫调节方面没有明显差异。这些特性被认为对益生菌很重要。根据这些结果，讨论了dlt操纵子在乳酸菌中的作用。
Lipoteichoic acid (LTA) is a macroamphiphile molecule which performs several functions in gram-positive bacteria, such as maintenance of cell wall homeostasis. D-Alanylation of LTA requires the proteins encoded by the dlt operon, and this process is directly related to the charge properties of this polymer strongly contributing to its function. The insertional inactivation of dltD of the probiotic strain Lactobacillus rhamnosus GG (ATCC 53103) resulted in the complete absence Of D-alanyl esters in the LTA as confirmed by nuclear magnetic resonance analysis. This was reflected in modifications of the bacterial cell surface properties. The dltD strain showed 2.4-fold-increased cell length, a low survival capacity in response to gastric juice challenge, an increased sensitivity to human beta-defensin-2, an increased rate of autolysis, an increased capacity to initiate growth in the presence of an anionic detergent, and a decreased capacity to initiate growth in the presence of cationic peptides compared to wild-type results. However, in vitro experiments revealed no major differences for adhesion to human intestinal epithelial cells, biofilm formation, and immunomodulation. These properties are considered to be important for probiotics. The role of the dlt operon in lactobacilli is discussed in view of these results.