Watanabe Yoko, Tsuboi Hideyuki, Koyama Michihisa, Kubo Momoji, Del Carpio Carlos A, Broclawik Ewa, Ichiishi Eiichiro, Kohno Masahiro, Miyamoto Akira
Department of Applied Chemistry, Graduate School of Engineering, Tohoku University, 6-6-11-1302 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan.
Comput Biol Chem. 2006 Aug;30(4):303-12. doi: 10.1016/j.compbiolchem.2006.04.004. Epub 2006 Jun 22.
The phagocyte NADPH oxidase complex plays a crucial role in host defense against microbial infection through the production of superoxides. Chronic granulomatous disease (CGD) is an inherited immune deficiency caused by the absence of certain components of the NADPH oxidase. Key to the activation of the NADPH oxidase is the cytoplasmic subunit p47phox, which includes the tandem SH3 domains (N-SH3 and C-SH3). In active phagocytes, p47phox forms a stable complex with the cytoplasmic region of membrane subunit p22phox that forms a left-handed polyproline type-II (PPII) helix conformation. In this report, we have analyzed the conformational changes of p47phox-p22phox complexes of wild-type and three mutants, which have been detected in CGD patients, using molecular dynamics simulations. We have found that in the wild-type, two basal planes of PPII prism in cytoplasmic region of p22phox interacted with N-SH3 and C-SH3. In contrast, in the modeled mutants, the residue at the ape of PPII helix, which interacts simultaneously with both of the tandem SH3 domains in the wild-type, moved toward C-SH3. Furthermore, interaction energies of the cytoplasmic region of p22phox with C-SH3 tend to decrease in these mutants. All these findings led us to conclude that interactions between N-SH3 of p47phox and PPII helix, which is formed by cytoplasmic region of p22phox, may play a significant role in the activation of the NADPH oxidase.
吞噬细胞NADPH氧化酶复合物通过产生超氧化物在宿主抵御微生物感染中发挥关键作用。慢性肉芽肿病（CGD）是一种遗传性免疫缺陷病，由NADPH氧化酶某些成分缺失引起。NADPH氧化酶激活的关键是细胞质亚基p47phox，其包含串联的SH3结构域（N-SH3和C-SH3）。在活化的吞噬细胞中，p47phox与膜亚基p22phox的细胞质区域形成稳定复合物，p22phox形成左手多聚脯氨酸II型（PPII）螺旋构象。在本报告中，我们使用分子动力学模拟分析了野生型和在CGD患者中检测到的三个突变体的p47phox-p22phox复合物的构象变化。我们发现，在野生型中，p22phox细胞质区域PPII棱柱的两个基面与N-SH3和C-SH3相互作用。相比之下，在模拟的突变体中，PPII螺旋顶端的残基（在野生型中与两个串联SH3结构域同时相互作用）向C-SH3移动。此外，在这些突变体中，p22phox细胞质区域与C-SH3的相互作用能趋于降低。所有这些发现使我们得出结论，p47phox的N-SH3与由p22phox细胞质区域形成的PPII螺旋之间的相互作用可能在NADPH氧化酶的激活中起重要作用。
