title: Calcium Regulates the Activity and Structural Stability of Tpr, a Bacterial Calpain-like Peptidase.
abstract: Porphyromonas gingivalis is a peptide-fermenting asaccharolytic periodontal pathogen. Its genome contains several genes encoding cysteine peptidases other than gingipains. One of these genes (PG1055) encodes a protein called Tpr (thiol protease) that has sequence similarity to cysteine peptidases of the papain and calpain families. In this study we biochemically characterize Tpr. We found that the 55-kDa Tpr inactive zymogen proteolytically processes itself into active forms of 48, 37, and 33 kDa via sequential truncations at the N terminus. These processed molecular forms of Tpr are associated with the bacterial outer membrane where they are likely responsible for the generation of metabolic peptides required for survival of the pathogen. Both autoprocessing and activity were dependent on calcium concentrations >1 mm, consistent with the protein's activity within the intestinal and inflammatory milieus. Calcium also stabilized the Tpr structure and rendered the protein fully resistant to proteolytic degradation by gingipains. Together, our findings suggest that Tpr is an example of a bacterial calpain, a calcium-responsive peptidase that may generate substrates required for the peptide-fermenting metabolism of P. gingivalis. Aside from nutrient generation, Tpr may also be involved in evasion of host immune response through degradation of the antimicrobial peptide LL-37 and complement proteins C3, C4, and C5. Taken together, these results indicate that Tpr likely represents an important pathogenesis factor for P. gingivalis.
authors.affiliation: Department of Microbiology, Faculty of Biochemistry, Biophysics, and Biotechnology, Jagiellonian University, 30-387 Krakow, Poland,; Department of Laboratory Medicine, Division of Clinical Chemistry and Pharmacology, Lund University, Lund, 22 100 Sweden,. Electronic address: dominika.staniec@uj.edu.pl.
authors.forename: Dominika
authors.initials: D
authors.lastname: Staniec
authors.affiliation: Department of Microbiology, Faculty of Biochemistry, Biophysics, and Biotechnology, Jagiellonian University, 30-387 Krakow, Poland,; Malopolska Center of Biotechnology, Jagiellonian University, 30-387 Krakow, Poland.
authors.forename: Miroslaw
authors.initials: M
authors.lastname: Ksiazek
authors.affiliation: Center for Insoluble Protein Structures (inSPIN) and Interdisciplinary Nanoscience Center (iNANO) at the Department of Molecular Biology, Aarhus University, Aarhus DK-8000, Denmark.
authors.forename: Ida B
authors.initials: IB
authors.lastname: Thøgersen
authors.affiliation: Center for Insoluble Protein Structures (inSPIN) and Interdisciplinary Nanoscience Center (iNANO) at the Department of Molecular Biology, Aarhus University, Aarhus DK-8000, Denmark.
authors.forename: Jan J
authors.initials: JJ
authors.lastname: Enghild
authors.affiliation: Department of Microbiology, Faculty of Biochemistry, Biophysics, and Biotechnology, Jagiellonian University, 30-387 Krakow, Poland.
authors.forename: Aneta
authors.initials: A
authors.lastname: Sroka
authors.affiliation: Department of Microbiology, Faculty of Biochemistry, Biophysics, and Biotechnology, Jagiellonian University, 30-387 Krakow, Poland.
authors.forename: Danuta
authors.initials: D
authors.lastname: Bryzek
authors.affiliation: Department of Pathology, Stanford University School of Medicine, Stanford, California 94305.
authors.forename: Matthew
authors.initials: M
authors.lastname: Bogyo
authors.affiliation: Department of Laboratory Medicine, Division of Clinical Chemistry and Pharmacology, Lund University, Lund, 22 100 Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Abrahamson
authors.affiliation: Department of Microbiology, Faculty of Biochemistry, Biophysics, and Biotechnology, Jagiellonian University, 30-387 Krakow, Poland,; Malopolska Center of Biotechnology, Jagiellonian University, 30-387 Krakow, Poland; Department of Oral Immunology and Infectious Diseases, University of Louisville School of Dentistry, Louisville, Kentucky 40202.
authors.forename: Jan
authors.initials: J
authors.lastname: Potempa
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism*; D002154:Calpain / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002364:Caseins / Q000378:metabolism; D020134:Catalytic Domain / Q000235:genetics; D002417:Cattle; D010450:Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D005340:Fibrinogen / Q000378:metabolism; D005353:Fibronectins / Q000378:metabolism; D005798:Genes, Bacterial; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016966:Porphyromonas gingivalis / Q000201:enzymology* / Q000235:genetics / Q000472:pathogenicity; D059748:Proteolysis; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D054804:Cathelicidins
chemical_list: D023181:Antimicrobial Cationic Peptides; D001426:Bacterial Proteins; D002364:Caseins; D005353:Fibronectins; D011994:Recombinant Proteins; D005340:Fibrinogen; D010450:Endopeptidases; D002154:Calpain; C115394:tpr protease; D002118:Calcium; D054804:Cathelicidins
keywords: calcium; calcium-dependent activity; calpain; enzyme processing; periodontal disease; virulence factor