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首页> 外文期刊>Infection and immunity >Activated complex of L-cells and Rickettsia prowazekii with N-ethylmaleimide-insensitive phospholipase A.
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Activated complex of L-cells and Rickettsia prowazekii with N-ethylmaleimide-insensitive phospholipase A.

机译：L细胞与立克次体立克次体与N-乙基马来酰亚胺不敏感的磷脂酶A的活化复合物。

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The interaction of large numbers of viable Rickettsia prowazekii cells with L-cells results in the expression of a phospholipase A activity with the concomitant release of free fatty acids and lysophosphatides from the phospholipids of the L-cell. About 50% of rickettsiae present in the suspension that was centrifuged onto an L-cell monolayer at 0 degree C to effect this interaction formed a tight L-cell-rickettsiae association from which the rickettsiae could not be removed by simple washing. Both the L-cell-rickettsiae association and the rickettsiae before association with L-cells interact with N-ethylmaleimide, so that the subsequent expression of the phospholipase A activity was inhibited (treatment of the L-cells with N-ethylmaleimide before centrifugation does not inhibit phospholipase activity). However, treatment of this association with 2,4-dinitrophenol and KCN caused much less inhibition of this phospholipase A activity than did treatment of the rickettsiae with these agents before centrifugation onto the L-cells. Incubation of the L-cell-rickettsiae association for a short time at 35 degrees C resulted in a very low level of free fatty acid formation and changed this association to an activated complex in which the phospholipase A activity was no longer sensitive to the inhibitory effects of N-ethylmaleimide. The characteristics of the association and activated complex were stable: after a 2-h incubation at 0 degrees C, the association and the activated complex retained both their basal phospholipase A activities and their characteristic responses to N-ethylmaleimide treatment. In scanning electron micrographs of the activated complexes, the rickettsiae that were initially attached were no longer visible after 45 min at 35 degrees C, and the surface of the L-cell appeared to have been etched away. These activated complexes provide a system in which modulators of the phospholipase A can be investigated without the confusion caused by the first-step receptor interaction between rickettsiae and their host cells.
机译：大量有活力的立克次体立克次体细胞与L细胞的相互作用导致磷脂酶A活性的表达，并伴随着L​​磷脂的游离脂肪酸和溶血磷脂的释放。悬浮液中存在的约50％的立克次体在0°C离心至L细胞单层以实现这种相互作用，形成了紧密的L细胞-立克次体缔合，无法通过简单洗涤将立克次体从中除去。 L细胞-立克次体缔合和与L细胞缔合前的立克次体均与N-乙基马来酰亚胺相互作用，因此磷脂酶A活性的后续表达受到抑制（离心前用N-乙基马来酰亚胺处理L细胞不会抑制磷脂酶活性）。然而，与2,4-二硝基苯酚和KCN进行这种结合的处理相比，在离心至L细胞之前，用这些药物处理立克次体的作用要少得多。 L细胞-立克次体在35°C下短时间孵育会导致极低水平的游离脂肪酸形成，并将这种结合改变为活化的复合物，其中磷脂酶A活性对抑制作用不再敏感N-乙基马来酰亚胺。缔合和活化的复合物的特性是稳定的：在0摄氏度孵育2小时后，缔合和活化的复合物既保留了其基础磷脂酶A的活性，又保留了对N-乙基马来酰亚胺处理的特征性反应。在活化复合物的扫描电子显微照片中，最初附着的立克次体在35℃45分钟后不再可见，并且L细胞的表面似乎已被蚀刻掉。这些活化的复合物提供了一种系统，其中可以研究磷脂酶A的调节剂，而不会由于立克次体与其宿主细胞之间的第一步受体相互作用而引起混淆。

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