title: The NOXO1β PX domain preferentially targets PtdIns(4,5)P2 and PtdIns(3,4,5)P3.
abstract: NOXO1β [NOXO1 (Nox organizer 1) β] is a cytosolic protein that, in conjunction with NOXA1 (Nox activator 1), regulates generation of reactive oxygen species by the NADPH oxidase 1 (Nox1) enzyme complex. NOXO1β is targeted to membranes through an N-terminal PX (phox homology) domain. We have used NMR spectroscopy to solve the structure of the NOXO1β PX domain and surface plasmon resonance (SPR) to assess phospholipid specificity. The solution structure of the NOXO1β PX domain shows greatest similarity to that of the phosphatidylinositol 3-kinase-C2α PX domain with regard to the positions and types of residues that are predicted to interact with phosphatidylinositol phosphate (PtdInsP) head groups. SPR experiments identify PtdIns(4,5)P(2) and PtdIns(3,4,5)P(3) as preferred targets of NOXO1β PX. These findings contrast with previous lipid overlay experiments showing strongest binding to monophosphorylated PtdInsP and phosphatidylserine. Our data suggest that localized membrane accumulation of PtdIns(4,5)P(2) or PtdIns(3,4,5)P(2) may serve to recruit NOXO1β and activate Nox1.
authors.affiliation: Department of Biochemistry, Wake Forest School of Medicine, Winston-Salem, NC 27157, USA.
authors.forename: Nicole Y
authors.initials: NY
authors.lastname: Davis
authors.forename: Linda C
authors.initials: LC
authors.lastname: McPhail
authors.forename: David A
authors.initials: DA
authors.lastname: Horita
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport / Q000737:chemistry* / Q000378:metabolism*; D000595:Amino Acid Sequence; D001665:Binding Sites; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000378:metabolism*; D018129:Phosphatidylinositol Phosphates / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D020349:Surface Plasmon Resonance
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D033942:Adaptor Proteins, Vesicular Transport; C476419:NOXO1 protein, human; D019269:Phosphatidylinositol 4,5-Diphosphate; D018129:Phosphatidylinositol Phosphates; C060974:phosphatidylinositol 3,4,5-triphosphate