Honbou Kazuya, Minakami Reiko, Yuzawa Satoru, Takeya Ryu, Suzuki Nobuo N, Kamakura Sachiko, Sumimoto Hideki, Inagaki Fuyuhiko
Laboratory of Structural Biology, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo, Japan.
EMBO J. 2007 Feb 21;26(4):1176-86. doi: 10.1038/sj.emboj.7601561. Epub 2007 Feb 8.
The superoxide-producing phagocyte NADPH oxidase is activated during phagocytosis to destroy ingested microbes. The adaptor protein p40phox associates via the PB1 domain with the essential oxidase activator p67phox, and is considered to function by recruiting p67phox to phagosomes; in this process, the PX domain of p40phox binds to phosphatidylinositol 3-phosphate [PtdIns(3)P], a lipid abundant in the phagosomal membrane. Here we show that the PtdIns(3)P-binding activity of p40phox is normally inhibited by the PB1 domain both in vivo and in vitro. The crystal structure of the full-length p40phox reveals that the inhibition is mediated via intramolecular interaction between the PB1 and PX domains. The interface of the p40phox PB1 domain for the PX domain localizes on the opposite side of that for the p67phox PB1 domain, and thus the PB1-mediated PX regulation occurs without preventing the PB1-PB1 association with p67phox.
产生超氧化物的吞噬细胞NADPH氧化酶在吞噬作用过程中被激活，以破坏摄入的微生物。衔接蛋白p40phox通过PB1结构域与必需的氧化酶激活剂p67phox结合，并被认为通过将p67phox募集到吞噬体来发挥作用；在此过程中，p40phox的PX结构域与磷脂酰肌醇3-磷酸[PtdIns(3)P]结合，PtdIns(3)P是吞噬体膜中丰富的一种脂质。我们在此表明，p40phox的PtdIns(3)P结合活性在体内和体外通常都受到PB1结构域的抑制。全长p40phox的晶体结构表明，这种抑制是通过PB1和PX结构域之间的分子内相互作用介导的。p40phox PB1结构域与PX结构域的界面位于与p67phox PB1结构域的界面相反的一侧，因此PB1介导的PX调节在不阻止PB1与p67phox的PB1结合的情况下发生。
