Aggregatibacter actinomycetemcomitans LtxC is required for leukotoxin activity and initial interaction between toxin and host cells
Aggregatibacter actinomycetemcomitans LtxC is required for leukotoxin activity and initial interaction between toxin and host cells
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DOI：
10.1016/j.gene.2009.05.002
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发表时间：
2009-08-15
期刊：
影响因子：
3.5
通讯作者：
Kachlany, Scott C.
中科院分区：
文献类型：
--
作者：
Balashova, Nataliya V.;Shah, Chintan;Kachlany, Scott C.
伴放线聚集杆菌（Aggregatibacteractinomycetemcomitans）是一种产生RTX毒素（毒素中的重复序列）、白细胞毒素（LtxA）的人类病原体。基于其他RTX毒素系统，预测ltx操纵子的第一个基因ltxC的产物参与LtxA的脂肪酸修饰。确定ltxC在A.在放线菌共生菌中，我们使用随机诱变在高白细胞毒性菌株JP2N中产生ltxC突变。来自ltxC突变体的毒素（LtxA（ltxc））被表达并分泌到细胞培养上清液中，但不能裂解人白细胞或红细胞。LtxA（ltxc）和来自菌株JP2N的LtxA（LtxA（wt））的质谱分析揭示了两种不同的肽，并且该数据表明来自野生型菌株的LtxA的两个内部赖氨酸残基被修饰。在阻断实验中，用LtxA（ltxc）预处理细胞不能阻止LtxA（wt）对细胞的杀伤，而且，与LtxA（wt）相反，LtxA（ltxc）不引起人白细胞内钙水平的增加。加在一起。我们的数据表明，ltxC是A中LtxA的完全活性和修饰所必需的。这种修饰对于毒素与宿主细胞的初始结合是重要的，如细胞内钙水平的增加所定义的。(C)2009爱思唯尔有限公司版权所有。
Aggregatibacter actinomycetemcomitans is a human pathogen that produces the RTX toxin (repeats in toxin), leukotoxin (LtxA). Based on other RTX toxin systems, the product of ltxC, the first gene of the ltx operon, is predicted to be involved in fatty acid modification of LtxA. To determine the function of ltxC in A. actinomycetemcomitans, we generated an ltxC mutation in the highly leukotoxic strain JP2N using random mutagenesis. The toxin from the ltxC mutant (LtxA(ltxc)) was expressed and secreted into the cell culture supernatant but could not lyse human leukocytes or erythrocytes. Mass spectrometric analysis of LtxA(ltxc) and LtxA from strain JP2N (LtxA(wt)) revealed two peptides that differed and this data suggests that two internal lysine residues of LtxA from the wild-type strain are modified. In blocking experiments, pre-treatment of cells with LtxA(ltxc) was unable to prevent LtxA(wt) from killing cells.Furthermore, in contrast to LtxA(wt), LtxA(ltxc) did not cause an increase in intracellular calcium levels in human leukocytes. Taken together. our data show that ltxC is required for full activity and modification of LtxA in A. actinomycetemcomitans and that modification is important for initial binding of toxin to host cells, as defined by an increase in intracellular calcium levels. (C) 2009 Elsevier B.V. All rights reserved.