Aggregatibacter actinomycetemcomitans leukotoxin requires β-sheets 1 and 2 of the human CD11a β-propeller for cytotoxicity
Aggregatibacter actinomycetemcomitans leukotoxin requires β-sheets 1 and 2 of the human CD11a β-propeller for cytotoxicity
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DOI：
10.1111/j.1462-5822.2007.00989.x
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发表时间：
2007-11-01
影响因子：
3.4
通讯作者：
Lally, Edward T.
中科院分区：
文献类型：
--
作者：
Kieba, Irene R.;Fong, Karen P.;Lally, Edward T.
伴放线菌聚集杆菌白细胞毒素（Ltx）是一种毒素重复序列（RTX）溶细胞素，可杀死携带人类白细胞功能相关抗原-1（LFA-1; alpha（L）/beta（2））的细胞。为了确定异源二聚体的α（L）部分是否参与Ltx识别，我们将人、小鼠和牛的α（L）cDNA转染到α（L）缺陷细胞系J-β（2）.7中，并寻找Ltx敏感性的恢复。表达牛或人α（L）与人β（2）的细胞被Ltx有效杀死，这表明牛α（L）可以在Ltx用于连接LFA-1的关键区域取代其人对应物。另一方面，表达鼠α（L）和人β（2）的细胞对Ltx的致死作用不敏感，表明毒素识别位点不存在于相应的小鼠序列中。为了进一步鉴定Ltx识别的α（L）区域，我们在J-β（2）.7细胞中构建并评估了一组嵌合的人/鼠α（L）基因。α（L）突变体组的分析表明，小鼠CD 11 a背景（包括人α（L）链β-螺旋桨β-折叠1和2的区域）上存在人N-末端128个氨基酸足以使Ltx细胞溶解。
Aggregatibacter actinomycetemcomitans leukotoxin (Ltx) is a repeats-in-toxin (RTX) cytolysin that kills human leukocyte function-associated antigen-1 (LFA-1; alpha(L)/beta(2))-bearing cells. In order to determine whether the alpha(L) portion of the heterodimer is involved in Ltx recognition, we transfected human, mouse and bovine alpha(L) cDNAs into J-beta(2).7, an alpha(L)-deficient cell line, and looked for restoration of Ltx susceptibility. Cells expressing either bovine or human alpha(L) in conjunction with human beta(2) were efficiently killed by Ltx, an indication that bovine alpha(L) could substitute for its human counterpart in critical regions used by Ltx for attachment to LFA-1. On the other hand, cells expressing murine alpha(L) and human beta(2) were not susceptible to the lethal effects of Ltx indicating that the toxin recognition sites are not present in the corresponding mouse sequence. To further identify the region(s) of alpha(L) recognized by Ltx, we constructed and evaluated a panel of chimeric human/murine alpha(L) genes in J-beta(2).7 cells. Analysis of the alpha(L) mutant panel showed that the presence of human N-terminal 128 amino acids on a mouse CD11a background, a region that includes beta-sheets 1 and 2 of the beta-propeller of the human alpha(L) chain, was sufficient for Ltx cytolysis.