The NOXO1β PX Domain Preferentially Targets PtdIns(4,5)P2 and PtdIns(3,4,5)P3

Abstract

NOXO1β is a cytosolic protein which, in conjunction with NOXA1, regulates generation of reactive oxygen species (ROS) by the Nox1 enzyme complex. NOXO1β is targeted to membranes through an N-terminal PX domain. We have used nuclear magnetic resonance spectroscopy to solve the structure of the NOXO1β PX domain and surface plasmon resonance to assess phospholipid specificity. The solution structure of the NOXO1β PX domain shows greatest similarity to the PI3K-C2α PX domain with regard to the positions and types of residues that are predicted to interact with phosphatidylinositol phosphate (PtdInsP) head groups. Surface plasmon resonance experiments identify PtdIns(4,5)P2 and PtdIns(3,4,5)P3 as preferred targets of NOXO1β PX. These findings contrast with previous lipid overlay experiments which show strongest binding to monophosphorylated PtdInsP and phosphatidylserine. Our data suggest that localized membrane accumulation of PtdIns(4,5)P2 or PtdIns(3,4,5)P2 may serve to recruit NOXO1β and activate Nox1.

Regulation of the Phosphoinositide Code by Phosphorylation of Membrane Readers

“…The literature was surveyed for lipid binding data for each PX domain, with the relevant PIP specificities for human and yeast proteins shown in Table 1 . Studies of PIP specificity and membrane affinity by PX domains of human proteins were examined including those of ARHGAP32 [ 3 , 20 ], ARHGAP33 [ 3 , 21 ], HS1BP3 [ 3 , 22 ], KIF16B [ 3 , 23 , 24 ], NISCH [ 3 , 25 ], NOXO1β [ 26 , 27 , 28 , 29 ], NOXO1γ [ 26 , 27 , 29 ], PIK3C2α [ 3 , 30 , 31 ], PIK3C2β [ 3 , 30 ], PLD1 [ 32 , 33 , 34 ], PLD2 [ 33 , 35 , 36 , 37 ], PXK [ 3 , 38 ], p40 phox [ 3 , 39 , 40 , 41 ], p47 phox [ 3 , 39 , 42 ], RPS6KC1 [ 3 , 43 , 44 ], SGK3 [ 3 , 45 , 46 ], SH3PXD2A [ 3 , 47 ], SH3PXD2B [ 47 , 48 ], SNX1 [ 3 , 49 , 50 ,…”