IBBMC, Université Paris XI, Bât. 430, 91405 Orsay Cedex, France; CNRS UMR8619, Orsay, France.
J Struct Biol. 2010 Jan;169(1):45-53. doi: 10.1016/j.jsb.2009.08.009. Epub 2009 Aug 31.
The NADPH oxidase complex is involved in the destruction of phagocytosed pathogens through the production of reactive oxygen species. This activatable complex consists of a membranous heterodimeric flavocytochrome b, a small G-protein Rac1/Rac2 and cytosolic factors, p47(phox), p67(phox) and p40(phox). p67(phox), due to its modular structure, is the NADPH oxidase component for which global structure information is most scarce despite its mandatory role in activation and its central position in the whole complex organization. Indeed, p67(phox) is the only factor establishing interaction with all others. In this study, we report the SAXS analysis of p67(phox). Our data reveals that p67(phox) behaves as a multidomain protein with semi-flexible linkers. On the one hand, it appears to be a very elongated molecule with its various domains organized as beads on a string. Linkers are predicted to be partially or mainly unstructured and features of our experimental data do point towards inter-domain flexibility. On the other hand, our work also suggests that the protein is not as extended as unstructured linkers could allow, thereby implying the existence of intra-molecular interactions within p67(phox). We suggest that the dual character of p67(phox) conformation in solution is central to ensure the numerous interactions to be accommodated.
NADPH 氧化酶复合物通过产生活性氧物质参与吞噬病原体的破坏。这种可激活的复合物由膜异二聚体 flavocytochrome b、小 G 蛋白 Rac1/Rac2 和胞质因子 p47(phox)、p67(phox)和 p40(phox)组成。由于其模块化结构，p67(phox)是 NADPH 氧化酶的组成部分，尽管它在激活中具有强制性作用且在整个复合物组织中处于核心地位，但全球结构信息却最为稀缺。事实上，p67(phox)是唯一与所有其他因子建立相互作用的因子。在这项研究中，我们报告了 p67(phox)的 SAXS 分析。我们的数据表明，p67(phox)表现为一种具有半柔性连接体的多结构域蛋白。一方面，它似乎是一种非常细长的分子，其各个结构域排列如串珠。预测连接体部分或主要无结构，我们的实验数据特征也指向结构域间的灵活性。另一方面，我们的工作还表明，该蛋白质并不像无结构连接体允许的那样伸展，从而意味着 p67(phox) 内存在分子内相互作用。我们认为，p67(phox)在溶液中的构象的双重特征对于确保容纳众多相互作用至关重要。
