Studies on the NADPH oxidase system responsible for anti-infectious activity of phagocytes

我们正在研究负责吞噬细胞抗感染活性的NADPH氧化酶系统的机制。慢性肉芽肿病（CGD）是一种遗传性疾病，患者体内不能产生超氧阴离子，易反复感染。1.Gp91是NADPH氧化酶的氧化还原中心，其分子中同时含有血红素和FAD。然而，这种黄素细胞色素的概念仅基于gp 91和其他黄素蛋白的氨基酸序列之间的相似性，没有任何直接证据。其主要原因是gp 91中的大多数突变导致其蛋白质完全缺失。我们发现了一个罕见的CGD患者谁表达的gp 91载脂蛋白。cDNA分析显示His-338突变为Try，其位于预测的FAD结合结构域。患者的生化分析显示，FAD完全丢失，体外添加试剂FAD无法纠正其产生超氧化物的活性。这些结果表明His-338对FAD掺入NADPH氧化酶是非常关键的。这是在CGD.2中发现的第一个这样的突变。还没有研究，询问NADPH氧化酶与微生物衍生毒素的关系。在这里，我们研究了曲霉菌胶毒素对NADPH氧化酶的影响。这种毒素，轴承的S-S键在其结构中，防止超氧化物生成的中性粒细胞NADPH氧化酶响应PMA的开始。胶粘毒素影响酶的活化过程，但不影响酶的催化作用。其抑制方式可能是胶质毒素的S-S键与NADPH氧化酶的巯基直接相互作用。

We are studying the mechanisms of the NADPH oxidase system responsible for anti-infectious activity of phagocytes. Patients with chronic granulomatous disease (CGD), a genetic disorder in this system, fail to generate superoxide anion and suffer from recurrent infections.1.Gp91, the redox center of the NADPH oxidase, had been considered to contain both heme and FAD in its molecule. However, this flavocytochrome concept was only based on the similarities between the amino acid sequences of gp91 and other flavoproteins, without any direct evidence. The main reason for this was that most of the mutations in gp91 lead complete absence of its protein. We discovered a rare CGD patient who expressed a gp91 apoprotein. Analysis of cDNA revealed the mutation of His-338 to Try, which resided in a predicted domain for FAD-binding. The biochemical analysis of the patient revealed that the lost FAD completely, and the addition of reagent FAD in vitro could not corrected his superoxide-generating activity. These resulted indicate that His-338 is a very critical for FAD incorporation into the NADPH oxidase. This was the first such mutation found in CGD.2. There have not been studies, which inquired the NADPH oxidase in relation to microorganism-derived toxins. Here, we investigated the effect of gliotoxin from Aspergillus on the NADPH oxidase. This toxin, bearing S-S bond in its structure, prevented the onset of superoxide generation by the neutrophil NADPH oxidase in response to PMA. Gliotoxin affected the activation process, but not the catalysis of the activated enzyme. The inhibitory mode was suggested to be direct interaction of S-S bond in gliotoxin with vicinal SH group in the NADPH oxidase.