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- Title
Binding of the PX domain of p47<sup>phox</sup> to phosphatidylinositol 3,4-bisphosphate and phosphatidic acid is masked by an intramolecular interaction.
- Authors
Karathanassis, Dimitrios; Stahelin, Robert V.; Bravo, Jerónimo; Perisic, Olga; Pacold, Christine M.; Cho, Wonhwa; Williams, Roger L.
- Abstract
p47phox is a key cytosolic subunit required for activation of phagocyte NADPH oxidase. The X-ray structure of the p47phox PX domain revealed two distinct basic pockets on the membrane-binding surface, each occupied by a sulfate. These two pockets have different specificities: one preferentially binds phosphatidylinositol 3,4-bisphosphate [Ptdlns(3,4)P2] and is analogous to the phophatidylinositol 3-phosphate (PtdIns3P)-binding pocket of p40phox, white the other binds anionic phospholipids such as phosphatidic acid (PtdOH) or phosphatidylserine. The preference of this second site for PtdOH may be related to previously observed activation of NADPH oxidase by PtdOH. Simultaneous occupancy of the two phospholipid-binding pockets radically increases membrane affinity. Strikingly, measurements for full-length p47phox show that membrane interaction by the PX domain is masked by an intramolecular association with the C-terminal SH3 domain (C-SH3). Either a site-specific mutation in C-SH3 (W263R) or a mimic of the phosphorylated form of p47phox [Ser(303, 304, 328, 359, 370)Glu] cause a transition from a closed to an open conformation that binds membranes with a greater affinity than the isolated PX domain.
- Publication
EMBO Journal, 2002, Vol 21, Issue 19, p5057
- ISSN
0261-4189
- Publication type
Academic Journal
- DOI
10.1093/emboj/cdf519