Characterization of leukotoxin from a clinical strain of Actinobacillus actinomycetemcomitans
Characterization of leukotoxin from a clinical strain of Actinobacillus actinomycetemcomitans
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DOI：
10.1016/j.micpath.2005.10.005
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发表时间：
2006-02-01
影响因子：
3.8
通讯作者：
Kachlany, SC
中科院分区：
文献类型：
--
作者：
Diaz, R;Al Ghofaily, L;Kachlany, SC
伴放线放线杆菌（Actinobacillusactinomycetemcomitans）是一种革兰氏阴性病原体，其是局部侵袭性牙周炎（localizedaggressiveperiodontitis，牙周炎）的病原体，牙周炎是一种主要影响青少年的快速进展和严重的口腔疾病。A.伴放线菌也见于口腔外感染，包括感染性心内膜炎。A.伴随放线菌产生RTX（毒素重复序列）外毒素，白细胞毒素（LtxA）。LtxA特异性杀死人类和旧世界猴的白细胞。我们目前对A. Actinomyceteincomitans LtxA是基于来自菌株JP2的蛋白质，菌株JP2是一种非粘附性实验室分离物。由于实验室分离株可丧失毒力特性，我们希望检查来自临床分离株NJ 14500的LtxA。我们发现，LtxA的本地化模式没有不同的菌株之间。用NJ4500进行的亚细胞定位研究表明，LtxA定位于外膜，并且LtxA与细胞表面之间的相互作用是特异性的。表面定位的LtxA没有被去除与NaCl处理和蛋白酶保护实验表明，约10 kDa的LtxA暴露。我们从NJ4500中纯化了分泌型LtxA，发现该毒素的比活性大于JP2分泌型LtxA。对于其他RTX毒素，脂肪酸修饰影响毒素活性，并且A.放线菌共生菌LtxA被修饰。我们通过二维凝胶电泳表明，NJ4500 LtxA比JP2 LtxA更高度修饰，这表明活性的差异可能是由于差异修饰。研究A.因此，伴放线菌的致病机理应考虑临床分离株的LtxA。(c)2005爱思唯尔有限公司保留所有权利。
Actinobacillus actinomycetemcomitans is a Gram negative pathogen that is the etiologic agent of localized aggressive periodontitis (LAP), a rapidly progressing and severe disease of the oral cavity that affects predominantly adolescents. A. actinomycetemcomitans is also found in extraoral infections including infective endocarditis. As one of its many virulence determinants, A. actinomycetemcomitans produces the RTX (repeats in toxin) exotoxin, leukotoxin (LtxA). LtxA specifically kills leukocytes of humans and Old World Monkeys. All of our current knowledge of A. actinomyceteincomitans LtxA is based on the protein from strain JP2, a nonadherent laboratory isolate. Because laboratory isolates can lose virulence properties, we wished to examine LtxA from a clinical isolate, NJ14500. We show that localization patterns of LtxA do not differ between the strains. Subcellular localization studies with NJ4500 revealed that LtxA localizes to the outer membrane and that the interaction between LtxA and the surface of cells is specific. Surface localized LtxA was not removed with NaCl treatment and protease protection experiments revealed that approximately 10 kDa of LtxA is exposed. We purified secreted LtxA from NJ4500 and found that the specific activity of this toxin was greater than that of secreted LtxA from JP2. For other RTX toxins, fatty acid modification affects toxin activity, and A. actinomycetemcomitans LtxA is predicted to be modified. We show by two-dimensional gel electrophoresis that NJ4500 LtxA is more highly modified than JP2 LtxA, suggesting that the difference in activities could be due to differential modification. Studies of A. actinomycetemcomitans pathogenesis should therefore consider LtxA from clinical isolates. (c) 2005 Elsevier Ltd. All rights reserved.