Part:BBa_K4160004

PR3 (proteinase 3)

Proteinase 3 (PR3) (Figure 1) is a neutrophilic serine protease that is present in neutrophil granules and at their membrane.¹ PR3 degrades extracellular proteins at sites of inflammation and is known the be involved in regulating the immune system.² This part encodes for a truncated form of PR3. The propeptide sequence was removed from the PR3 sequence to eliminate the independent biological function of PR3.³ The TU-Eindhoven team 2022 fused this part to the EpoR (BBa_K4160001) to generate the GEMS receptor (BBa_K4160009 & BBa_K4160012).

Figure 1 | 3D structure of PR3. (AlphaFold: AF-D6CHE9-F1).⁴

Sequence and Features

Assembly Compatibility:

• 10
  INCOMPATIBLE WITH RFC[10]

  Illegal PstI site found at 122
  
• 12
  INCOMPATIBLE WITH RFC[12]

  Illegal PstI site found at 122
  
• 21
  COMPATIBLE WITH RFC[21]
• 23
  INCOMPATIBLE WITH RFC[23]

  Illegal PstI site found at 122
  
• 25
  INCOMPATIBLE WITH RFC[25]

  Illegal PstI site found at 122
  
• 1000
  COMPATIBLE WITH RFC[1000]

Usage and Biology

PR3 originates from the Homo sapiens (Human)⁴ It is part of the "chymotrypsin"-like neutrophil serine proteinase family, which is identified by highly considered catalytic triads for proteolytic activity.⁵ PR3 is a highly abundantly present neutrophilic protein that is transcribed in primitive monocytic and myeloid progenitor cells and expressed in granulocyte and monocyte cell lineages.⁵ PR3 is mainly expressed in neutrophils, but also mast cells and basophils. In healthy individuals, PR3 is expressed on the cellular membrane of naïve neutrophils that reside in the peripheral blood. After granule translocation to the cellular membrane, activated neutrophils secrete PR3 into the extracellular medium.⁵ PR3 operates in the immune response of neutrophils. Its function is to regulate cellular processes, activate pro-inflammatory cytokines, and cleave host proteins into antibacterial peptides.⁵

ANCA-associated vasculitis

PR3 is an important target in ANCA-associated vasculitis, an autoimmune disease characterized by necrosis in the small blood vessels.⁶ ANCA-associated vasculitis is associated with the production of pathogenic antineutrophil cytoplasmic antibodies (ANCAs), which can interact with PR3.⁶ Binding of ANCAs to PR3 allows for activation of an autoimmune reaction that results in small-vessel vasculitis and granulomatous inflammation.⁶

GEMS receptor

TU-Eindhoven 2022 used this part as an affinity domain for the Generalized Extracellular Molecule Sensor (GEMS) receptors (BBa_K416009 & BBa_K4160012). Upon binding of ANCAs to the PR3 affinity domains, the GEMS receptor should dimerize and induce the JAK/STAT pathway (Figure 2).

Figure 2 | Activation of GEMS receptor containing PR3. In the presence of ANCAs, the GEMS receptor activates through a conformational change between the two receptor subunits.

Characterization

Characterization of PR3 as an affinity domain of the GEMS receptor can be found on the BBa_K4160009, BBa_K4160010, BBa_K41600012 & BBa_K4160013 pages.

References

1. Granel J, Korkmaz B, Nouar D, et al. Pathogenicity of Proteinase 3-Anti-Neutrophil Cytoplasmic Antibody in Granulomatosis With Polyangiitis: Implications as Biomarker and Future Therapies. Front Immunol. 2021;12. doi:10.3389/FIMMU.2021.571933
2. Sugawara S. Immune Functions of Proteinase 3. Crit Rev Immunol. 2005;25(5):343-359. doi:10.1615/CRITREVIMMUNOL.V25.I5.10
3. PRTN3 - Myeloblastin - Homo sapiens (Human) | UniProtKB | UniProt. Accessed October 11, 2022. https://www.uniprot.org/uniprotkb/P24158/entry#structure
4. Crisford H, Sapey E, Stockley RA. Proteinase 3; a potential target in chronic obstructive pulmonary disease and other chronic inflammatory diseases. Respir Res 2018 191. 2018;19(1):1-10. doi:10.1186/S12931-018-0883-5
5. Kallenberg CGM. Pathogenesis of PR3-ANCA associated vasculitis. J Autoimmun. 2008;30(1-2):29-36. doi:10.1016/J.JAUT.2007.11.005