Phosphorylation of p47phox directs phox homology domain from SH3 domain toward phosphoinositides, leading to phagocyte NADPH oxidase activation
AUTOR(ES)
Ago, Tetsuro
FONTE
The National Academy of Sciences
RESUMO
Protein–phosphoinositide interaction participates in targeting proteins to membranes where they function correctly and is often modulated by phosphorylation of lipids. Here we show that protein phosphorylation of p47phox, a cytoplasmic activator of the microbicidal phagocyte oxidase (phox), elicits interaction of p47phox with phosphoinositides. Although the isolated phox homology (PX) domain of p47phox can interact directly with phosphoinositides, the lipid-binding activity of this protein is normally suppressed by intramolecular interaction of the PX domain with the C-terminal Src homology 3 (SH3) domain, and hence the wild-type full-length p47phox is incapable of binding to the lipids. The W263R substitution in this SH3 domain, abrogating the interaction with the PX domain, leads to a binding of p47phox to phosphoinositides. The findings indicate that disruption of the intramolecular interaction renders the PX domain accessible to the lipids. This conformational change is likely induced by phosphorylation of p47phox, because protein kinase C treatment of the wild-type p47phox but not of a mutant protein with the S303/304/328A substitution culminates in an interaction with phosphoinositides. Furthermore, although the wild-type p47phox translocates upon cell stimulation to membranes to activate the oxidase, neither the kinase-insensitive p47phox nor lipid-binding-defective proteins, one lacking the PX domain and the other carrying the R90K substitution in this domain, migrates. Thus the protein phosphorylation-driven conformational change of p47phox enables its PX domain to bind to phosphoinositides, the interaction of which plays a crucial role in recruitment of p47phox from the cytoplasm to membranes and subsequent activation of the phagocyte oxidase.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=153580Documentos Relacionados
- Specificity of p47phox SH3 domain interactions in NADPH oxidase assembly and activation.
- Modulation of p47PHOX activity by site-specific phosphorylation: Akt-dependent activation of the NADPH oxidase
- PR-39, a proline-rich antibacterial peptide that inhibits phagocyte NADPH oxidase activity by binding to Src homology 3 domains of p47 phox.
- HBP1 Repression of the p47phox Gene: Cell Cycle Regulation via the NADPH Oxidase
- Multiple SH3 domain interactions regulate NADPH oxidase assembly in whole cells.