title: Atypical membrane-embedded phosphatidylinositol 3,4-bisphosphate (PI(3,4)P2)-binding site on p47(phox) Phox homology (PX) domain revealed by NMR.
abstract: The Phox homology (PX) domain is a functional module that targets membranes through specific interactions with phosphoinositides. The p47(phox) PX domain preferably binds phosphatidylinositol 3,4-bisphosphate (PI(3,4)P(2)) and plays a pivotal role in the assembly of phagocyte NADPH oxidase. We describe the PI(3,4)P(2) binding mode of the p47(phox) PX domain as identified by a transferred cross-saturation experiment. The identified PI(3,4)P(2)-binding site, which includes the residues of helices α1 and α1' and the following loop up to the distorted left-handed PP(II) helix, is located at a unique position, as compared with the phosphoinositide-binding sites of all other PX domains characterized thus far. Mutational analyses corroborated the results of the transferred cross-saturation experiments. Moreover, experiments with intact cells demonstrated the importance of this unique binding site for the function of the NADPH oxidase. The low affinity and selectivity of the atypical phosphoinositide-binding site on the p47(phox) PX domain suggest that different types of phosphoinositides sequentially bind to the p47(phox) PX domain, allowing the regulation of the multiple events that characterize the assembly and activation of phagocyte NADPH oxidase.
authors.affiliation: Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033; Japan Biological Informatics Consortium, Tokyo 104-0032.
authors.forename: Pavlos
authors.initials: P
authors.lastname: Stampoulis
authors.affiliation: Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033.
authors.forename: Takumi
authors.initials: T
authors.lastname: Ueda
authors.affiliation: Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033.
authors.forename: Masahiko
authors.initials: M
authors.lastname: Matsumoto
authors.affiliation: Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Terasawa
authors.affiliation: Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582.
authors.forename: Kei
authors.initials: K
authors.lastname: Miyano
authors.affiliation: Graduate School of Medical Sciences, Kyushu University, Fukuoka 812-8582.
authors.forename: Hideki
authors.initials: H
authors.lastname: Sumimoto
authors.affiliation: Graduate School of Pharmaceutical Sciences, University of Tokyo, Tokyo 113-0033; Biomedicinal Information Research Center, National Institute of Advanced Industrial Science and Technology, Tokyo 135-0064, Japan. Electronic address: shimada@iw-nmr.f.u-tokyo.ac.jp.
authors.forename: Ichio
authors.initials: I
authors.lastname: Shimada
mesh_terms: D001665:Binding Sites; D004789:Enzyme Activation / Q000502:physiology; D006801:Humans; D019255:NADPH Oxidases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D018129:Phosphatidylinositol Phosphates / Q000737:chemistry* / Q000378:metabolism; D017433:Protein Structure, Secondary
chemical_list: D018129:Phosphatidylinositol Phosphates; C060980:phosphatidylinositol 3,4-diphosphate; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1