CYTOSOLIC PHOX PROTEINS INTERACT WITH AND REGULATE THE ASSEMBLY OF CORONIN IN NEUTROPHILS

The NADPH oxidase generates microbicidal superoxide in phagocytes, and when defective it leads to chronic granulomatous disease (CGD), Oxida se specific proteins in the cytosol, p47(phox) and p67(phox), as well as the small GTP binding protein p21rac are important for activation o f superoxide production, Because the activity of this oxidase is norma lly tightly restricted to the phagocytic vacuole, and its temporal and spatial organisation might he regulated by cytoskeletal proteins, we examined the cytosolic phox proteins for interactions with cytoskeleta l elements, p67(phox) copurified with a 57 kDa protein, identified as coronin, an actin binding protein that is important for movement and p hagocytosis in Dictyostelium. Binding studies revealed that coronin at taches to the C-terminal half of p40(phox) a binding partner of p67(ph ox). The phox proteins and coronin had a similar distribution in the c ell, and both accumulated around the phagocytic vacuole, PMA activatio n of adherent neutrophils resulted in a major rearrangement of these p roteins, and of actin, which were lost from the periphery of the cell and condensed around the nucleus, The rearrangement of F-actin and cor onin in adherent cells, were absent, or markedly diminished, in cells from patients lacking p47(phox) or p67(phox) in which an abnormally la rge proportion of the coronin was present as part of a large complex, The cytosolic phox proteins might play a regulatory role in the reorga nisation of the cytoskeleton accompanying superoxide generation.