A monoclonal antibody (MCPR3-7) interfering with the activity of proteinase 3 by an allosteric mechanism.
J. Biol. Chem. 288, 26635-26648 (2013)
Proteinase 3 (PR3) is an abundant serine protease of neutrophil granules and a major target of autoantibodies (PR3 anti-neutrophil cytoplasmic antibodies) in granulomatosis with polyangiitis. Some of the PR3 synthesized by promyelocytes in the bone marrow escapes the targeting to granules and occurs on the plasma membrane of naive and primed neutrophils. This membrane-associated PR3 antigen may represent pro-PR3, mature PR3, or both forms. To discriminate between mature PR3 and its inactive zymogen, which have different conformations, we generated and identified a monoclonal antibody called MCPR3-7. It bound much better to pro-PR3 than to mature PR3. This monoclonal antibody greatly reduced the catalytic activity of mature PR3 toward extended peptide substrates. Using diverse techniques and multiple recombinant PR3 variants, we characterized its binding properties and found that MCPR3-7 preferentially bound to the so-called activation domain of the zymogen and changed the conformation of mature PR3, resulting in impaired catalysis and inactivation by α1-proteinase inhibitor (α1-antitrypsin). Noncovalent as well as covalent complexation between PR3 and α1-proteinase inhibitor was delayed in the presence of MCPR3-7, but cleavage of certain thioester and paranitroanilide substrates with small residues in the P1 position was not inhibited. We conclude that MCPR3-7 reduces PR3 activity by an allosteric mechanism affecting the S1' pocket and further prime side interactions with substrates. In addition, MCPR3-7 prevents binding of PR3 to cellular membranes. Inhibitory antibodies targeting the activation domain of PR3 could be exploited as highly selective inhibitors of PR3, scavengers, and clearers of the PR3 autoantigen in granulomatosis with polyangiitis.
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Publication type
Article: Journal article
Document type
Scientific Article
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Keywords
Allostery; Antibodies; Autoimmunity; Neutrophil; Protease; Protease Inhibitor; Proteinase 3; Thermophoresis; Zymogen; α1-Proteinase Inhibitor; Antineutrophil Cytoplasmic Antibodies; Wegeners-granulomatosis; Serine Proteases; Neutrophil Elastase; Crystal-structure; Immune-system; Cathepsin-g; Pr3; Autoantigen; Distinct
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Language
english
Publication Year
2013
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2013
ISSN (print) / ISBN
0021-9258
e-ISSN
1083-351X
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Volume: 288,
Issue: 37,
Pages: 26635-26648
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American Society for Biochemistry and Molecular Biology
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Bethesda
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Peer reviewed
POF-Topic(s)
30202 - Environmental Health
Research field(s)
Lung Research
PSP Element(s)
G-501600-005
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Erfassungsdatum
2013-12-31