Activation of the phagocyte NADPH oxidase requires the regulatory proteins p47phox and p67phox, each harboring two SH3 domains. p67phox interacts with p47phox via simultaneous binding of the p67phox C-terminal SH3 domain to both the proline-rich region (PRR) of amino acid residues 360-369 and its C-terminally flanking region of p47phox; the role of the interaction in oxidase regulation has not been fully understood. Here we show that the p47phox-p67 phox interaction is disrupted not only by deletion of the PRR but also by substitution for basic residues in the extra-PRR (K383E/K385E). The substitution impaired oxidase activation partially in vitro and much more profoundly in vivo, indicating the significance of the p47phox extra-PRR. Replacement of Ser-379 in the extra-PRR, a residue known to undergo phosphorylation in stimulated cells, by aspartate attenuates the interaction and thus results in a defective superoxide production, suggesting that phosphorylation of Ser-379 is involved in oxidase regulation.
All Science Journal Classification (ASJC) codes
- Molecular Biology