Activation of the phagocyte NADPH oxidase involves a conformational change in Nox2. The effector in this process is p67phox and there is evidence for a change in the configuration of p67phox being required for binding to Nox2. To study this, we measured binding of p67phox to a library of Nox2 peptides and binding of NusA–Nox2 fusion proteins to p67phox. We found, serendipitously, that deletion of residues 259–279 in p67phox (p67phoxΔ(259–279)), endowed it with the ability to bind selectively to Nox2 peptide 369–383 (peptide 28). There was no binding to scrambled Nox2 peptide 28 and to Nox4 peptide 28. Binding was cysteine independent and resistant to reducing and alkylating agents. Truncations of peptide 28 revealed that the actual binding site consisted of residues 375–383. Binding of p67phoxΔ(259–279) to peptide 28 was mimicked by that of a (p67phox‐RacGTP) chimera. Both p67phoxΔ(259–279) and the (p67pho–RacGTP) chimera bound a NusA–Nox2 fusion protein, comprising residues 375–383. Specific single residue deletion mutants, within the p67phox sequence 259–279, were also bound to Nox2 peptide 28. Peptides synthesized to correspond to the 259–279 sequence in p67phox, were found to autobind p67phox, suggesting that an intramolecular bond exists in p67phox, one pole of which was located within residues 259–279. We conclude that “resting” p67phox exists in a “closed” conformation, generated by an intramolecular bond. Deletion of specific residues within the 259–279 sequence, in vitro, or interaction with RacGTP, in vivo, causes “opening” of the bond and results in binding of p67phox to a specific, previously unknown, site in Nox2.

Animals must eat, necessitating their encounter with food. At least one of the two, predator or prey, must move for the two to meet. Many predators forage for prey by one of two strategies, or foraging modes. They forage either actively, in which case their prey may be mobile or sessile, or passively by waiting in ambush, depending on prey motility. These two foraging modes have been studied extensively in lizards as a model organism (Cooper 1995, Huey & Pianka 1981, Pianka 1966, Pietruzska 1986). Many aspects of a species' biology are correlated with its foraging mode. For example, active foragers employ their chemosensory apparatus for following the prey's trail. Sit-and-wait foragers rely on their eyes to identify approaching prey (Cooper 1995). Other differences are briefly referenced elsewhere (Werner et al. 1997, 2004).