A 29-kDa protein associated with p67phox expresses both peroxiredoxin and phospholipase A2 activity and enhances superoxide anion production by a cell-free system of NADPH oxidase activity.
Production of toxic oxygen metabolites provides a mechanism for microbicidal activity of the neutrophil. The NADPH oxidase enzyme system initiates the production of oxygen metabolites by reducing oxygen to form superoxide anion (O(2)()). With stimulation of the respiratory burst, cytosolic oxidase components, p47(phox), p67(phox), and Rac, translocate to the phagolysomal and plasma membranes where they form a complex with cytochrome b(558) and express enzyme activity. A 29-kDa neutrophil protein (p29) was identified by co-immunoprecipitation with p67(phox). N-terminal sequence analysis of p29 revealed homology to an open reading frame gene described in a myeloid leukemia cell line. A cDNA for p29 identical to the open reading frame protein was amplified from RNA of neutrophils. Significant interaction between p29 and p67(phox) was demonstrated using a yeast two-hybrid system. A recombinant (rh) p29 was expressed in Sf9 cells resulting in a protein with an apparent molecular weight of 34,000. The rh-p29 showed immunoreactivity with the original rabbit antiserum that detected p47(phox) and p67(phox). In addition, rh-p29 exhibited PLA(2) activity, which was Ca(2+) independent, optimal at low pH, and preferential for phosphatidylcholine substrates. The recombinant protein protected glutathione synthetase and directly inactivated H(2)O(2). By activity and sequence homology, rh-p29 can be classified as a peroxiredoxin. Finally, O(2)() production by plasma membrane and recombinant cytosolic oxidase components in the SDS-activated, cell-free NADPH oxidase system were enhanced by rh-p29. This effect was not inhibited by PLA(2) inhibitors. Thus, p29 is a novel protein that associates with p67 and has peroxiredoxin activity. This protein has a potential role in protecting the NADPH oxidase by inactivating H(2)O(2) or altering signaling pathways affected by H(2)O(2).
Bonfils Blood Center, Denver, Colorado 80230, USA.
Patrick J
PJ
Leavey
Carolina
C
Gonzalez-Aller
Gail
G
Thurman
Michael
M
Kleinberg
Lori
L
Rinckel
Daniel W
DW
Ambruso
Stefanie
S
Freeman
Frans A
FA
Kuypers
Daniel R
DR
Ambruso
D000818:Animals; D000975:Antioxidants / Q000302:isolation & purification / Q000378:metabolism*; D002458:Cell Fractionation; D002474:Cell-Free System; D005974:Glutamate-Ammonia Ligase / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D008970:Molecular Weight; D019255:NADPH Oxidases / Q000378:metabolism*; D009504:Neutrophils / Q000166:cytology / Q000378:metabolism; D016877:Oxidants / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D010544:Peroxidases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D054464:Peroxiredoxins; D010741:Phospholipases A / Q000378:metabolism*; D054467:Phospholipases A2; D010750:Phosphoproteins / Q000378:metabolism*; D011485:Protein Binding; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
D000975:Antioxidants; D016877:Oxidants; D010750:Phosphoproteins; D011994:Recombinant Proteins; C079789:neutrophil cytosol factor 67K; D013481:Superoxides; D006861:Hydrogen Peroxide; D010544:Peroxidases; D054464:Peroxiredoxins; D019255:NADPH Oxidases; D010741:Phospholipases A; D054467:Phospholipases A2; D005974:Glutamate-Ammonia Ligase; D010100:Oxygen