Molecular mechanism for activation of the reactive-oxygen-species-producing phagocyte NADPH oxidaae that is involved in host defense

NADPH氧化酶是一种产生活性氧的酶，在寄主防御中起着至关重要的作用。吞噬细胞NADPH氧化酶的催化核心是膜结合的细胞色素Fb&lt；558&gt；，由gp91；lt；Phox&gt；和p22^&lt；Phox&gt；酶的激活需要刺激诱导特定的适配蛋白(p47^&lt；Phox&gt；，p67^&lt；Phox&gt；和P0^&lt；Phox&gt；，每个都包含SH3结构域)的膜移位：它们与膜上的细胞色素相互作用。在本项目中，我们研究了氧化酶激活的分子机制，并获得了以下新的发现：(1)我们发现p47^；lt；Phox&gt；通过两个SH3结构域与p22^&lt；Phox&gt；结合，这种相互作用识别p22^&lt；Phox&gt；的一个富含脯氨酸的区域(PRR)，这种相互作用是酶激活所必需的。(2)我们发现p47；lt；Phox&gt；的px结构域的磷脂酰肌醇结合活性是吞噬细胞氧化酶激活所必需的。(3)我们发现p67^；lt；Phox&gt；通过C-末端SH3结构域与p47^&lt；Phox&gt；以一种新的方式相互作用，并确定了p67^&lt；Phox&gt；SH3结构域与p47^&lt；Phox&gt；Prr之间的配合物的核磁共振结构。(4)我们已经证明，p40；；Phox&gt；通过促进p47；lt；Phox&gt；和p67^&lt；Phox&gt；的膜转位而促进了氧化酶的激活，这种作用是通过与p67^&lt；Phox&gt；的相互作用来实现的。(5)我们鉴定并克隆了p47；lt；Phox&gt；和p67^&lt；Phox&gt；分别命名为p41；lt；NOx&gt；和p51^&lt；NOx&gt；的新同源物，表明p41^&lt；NOx&gt；和p51^&lt；NOx&gt；不仅可以激活gp91；

The NADPH oxidase is an enzyme that produces reactive oxygen species, which play a crucial role in host defense. The catalytic core of the phagocyte NADPH oxidase is membrane-integrated cytochrome fb_<558>, comprising gp91^<phox> and p22^<phox>. Activation of the oxidase requires stimulus-induced membrane translocation of specific adaptor proteins(p47^<phox>,p67^<phox>, and p0^<phox>, each containing SH3 domain) : they interact with the cytochrome at the membrane. In the present project, we investigated the molecular mechanism for the oxidase activation, and obtained the following novel findings, (1)We have shown that p47^<phox> binds to p22^<phox> via the two SH3 domains in a manner where they recognize one proline-rich region(PRR) of p22^<phox> ; this interaction is essential for the oxidase activation. (2)We have revealed that the phosphoinositide-binding activity of the PX domain of p47^<phox> is required for activation of the phagocyte oxidase. (3)We have shown that p67^<phox> interacts with p47^<phox> via the C-terminal SH3 domain in a novel fashion, and determined the NMR structure of a complex between the p67^<phox> SH3 domain and the p47^<phox> PRR. (4)We have demonstrated that p40^<phox> facilitates the oxidase activation by enhancing the membrane translocation of p47^<phox> and p67^<phox> which effect is mediated via its interaction with p67^<phox>. (5)We have identified and cloned novel homologues of p47^<phox> and p67^<phox>, designated p41^<nox> and p51^<nox>, respectively, and shown that p41^<nox> and p51^<nox> can activate not only gp91^<phox> but also Nox1.