Format

Send to

Choose Destination
J Biol Chem. 2014 Nov 21;289(47):32481-7. doi: 10.1074/jbc.C114.617142. Epub 2014 Oct 16.

Peptidyl arginine deiminase from Porphyromonas gingivalis abolishes anaphylatoxin C5a activity.

Author information

1
From the Department of Laboratory Medicine, Medical Protein Chemistry, Lund University, SE-205 02 Malmö, Sweden, the Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Krakow, Poland.
2
the Department of Molecular Biology and Genetics and Interdisciplinary Nanoscience Center, Aarhus University, DK-8000 Aarhus, Denmark.
3
the Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, 30-387 Krakow, Poland.
4
From the Department of Laboratory Medicine, Medical Protein Chemistry, Lund University, SE-205 02 Malmö, Sweden.
5
the Department of Oral Immunology and Infectious Diseases, University of Louisville School of Dentistry, Louisville, Kentucky 40202, and.
6
the Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, New Mexico 87131.
7
From the Department of Laboratory Medicine, Medical Protein Chemistry, Lund University, SE-205 02 Malmö, Sweden, anna.blom@med.lu.se.

Abstract

Evasion of killing by the complement system, a crucial part of innate immunity, is a key evolutionary strategy of many human pathogens. A major etiological agent of chronic periodontitis, the Gram-negative bacterium Porphyromonas gingivalis, produces a vast arsenal of virulence factors that compromise human defense mechanisms. One of these is peptidylarginine deiminase (PPAD), an enzyme unique to P. gingivalis among bacteria, which converts Arg residues in polypeptide chains into citrulline. Here, we report that PPAD citrullination of a critical C-terminal arginine of the anaphylatoxin C5a disabled the protein function. Treatment of C5a with PPAD in vitro resulted in decreased chemotaxis of human neutrophils and diminished calcium signaling in monocytic cell line U937 transfected with the C5a receptor (C5aR) and loaded with a fluorescent intracellular calcium probe: Fura-2 AM. Moreover, a low degree of citrullination of internal arginine residues by PPAD was also detected using mass spectrometry. Further, after treatment of C5 with outer membrane vesicles naturally shed by P. gingivalis, we observed generation of C5a totally citrullinated at the C-terminal Arg-74 residue (Arg74Cit). In stark contrast, only native C5a was detected after treatment with PPAD-null outer membrane vesicles. Our study suggests reduced antibacterial and proinflammatory capacity of citrullinated C5a, achieved via lower level of chemotactic potential of the modified molecule, and weaker cell activation. In the context of previous studies, which showed crosstalk between C5aR and Toll-like receptors, as well as enhanced arthritis development in mice infected with PPAD-expressing P. gingivalis, our findings support a crucial role of PPAD in the virulence of P. gingivalis.

KEYWORDS:

Bacteria; Chemotaxis; Complement System; Inflammation; Periodontal Disease

PMID:
25324545
PMCID:
PMC4239603
DOI:
10.1074/jbc.C114.617142
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center