Punj Vasu, Sharma Rachna, Zaborina Olga, Chakrabarty A M
Department of Microbiology and Immunology, University of Illinois College of Medicine, Chicago, Illinois 60612, USA.
J Bacteriol. 2003 May;185(10):3167-78. doi: 10.1128/JB.185.10.3167-3178.2003.
We previously demonstrated that several clinical and environmental isolates of Burkholderia cepacia secreted ATP-utilizing enzymes to the medium; the secretion of these enzymes by cystic fibrosis lung isolate strain 38 was shown to be greatly enhanced in the presence of alpha(2)-macroglobulin. Fractionation of the growth medium of cystic fibrosis isolate strain 71 belonging to genomovar I demonstrated the presence of two additional proteins, homologues of Pseudomonas aeruginosa azurin and cytochrome c(551), which are normally involved in electron transfer during denitrification. A Q-Sepharose column flowthrough fraction of the growth medium of B. cepacia strain 71 enriched with the azurin and cytochrome c(551) homologues triggered apoptosis in macrophages and mast cells, leading to their death. Incubation of the Q-Sepharose column flowthrough fraction with antiazurin and anti-cytochrome c(551) antibodies greatly reduced cell death. We cloned and hyperexpressed a gene from B. cepacia strain 71 that encodes the homologue of P. aeruginosa azurin. Such azurin homologues were detected in the growth medium of several strains belonging to genomovars I, III, and VI but not in the growth medium of strains belonging to other genomovars. The growth medium of the strains that elaborated the azurin homologue had high cytotoxicity towards macrophages. Purified azurin homologue was shown to induce apoptosis in macrophages in a caspase-dependent manner and was localized in both the cytosol and nucleus when incubated with or microinjected into macrophages. This is an interesting example of the interaction of a bacterial protein normally involved in cellular energetics with macrophages to effect their cell death.
我们先前证明，洋葱伯克霍尔德菌的几种临床和环境分离株会向培养基中分泌利用ATP的酶；囊性纤维化肺分离株38分泌这些酶的情况在α(2)-巨球蛋白存在时显著增强。对属于基因变种I的囊性纤维化分离株71的生长培养基进行分级分离，发现了另外两种蛋白质，它们是铜绿假单胞菌天青蛋白和细胞色素c(551)的同源物，通常在反硝化过程中参与电子传递。富含天青蛋白和细胞色素c(551)同源物的洋葱伯克霍尔德菌71菌株生长培养基的Q-琼脂糖柱流穿级分可引发巨噬细胞和肥大细胞凋亡，导致它们死亡。用抗天青蛋白和抗细胞色素c(551)抗体孵育Q-琼脂糖柱流穿级分可大大减少细胞死亡。我们克隆并超表达了来自洋葱伯克霍尔德菌71菌株的一个基因，该基因编码铜绿假单胞菌天青蛋白的同源物。在属于基因变种I、III和VI的几个菌株的生长培养基中检测到了这种天青蛋白同源物，但在属于其他基因变种的菌株的生长培养基中未检测到。产生天青蛋白同源物的菌株的生长培养基对巨噬细胞具有高细胞毒性。纯化的天青蛋白同源物被证明以半胱天冬酶依赖性方式诱导巨噬细胞凋亡，并且在与巨噬细胞孵育或显微注射到巨噬细胞中时定位于细胞质和细胞核中。这是一个通常参与细胞能量代谢的细菌蛋白与巨噬细胞相互作用导致其细胞死亡的有趣例子。
