1. Calcium Regulates the Activity and Structural Stability of Tpr, a Bacterial Calpain-like Peptidase.
- Author
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Staniec D, Ksiazek M, Thøgersen IB, Enghild JJ, Sroka A, Bryzek D, Bogyo M, Abrahamson M, and Potempa J
- Subjects
- Amino Acid Sequence, Animals, Antimicrobial Cationic Peptides metabolism, Bacterial Proteins chemistry, Bacterial Proteins genetics, Calpain chemistry, Calpain genetics, Calpain metabolism, Caseins metabolism, Catalytic Domain genetics, Cattle, Endopeptidases chemistry, Endopeptidases genetics, Enzyme Stability, Fibrinogen metabolism, Fibronectins metabolism, Genes, Bacterial, Humans, Kinetics, Molecular Sequence Data, Mutagenesis, Site-Directed, Porphyromonas gingivalis genetics, Porphyromonas gingivalis pathogenicity, Proteolysis, Recombinant Proteins chemistry, Recombinant Proteins genetics, Recombinant Proteins metabolism, Substrate Specificity, Cathelicidins, Bacterial Proteins metabolism, Calcium metabolism, Endopeptidases metabolism, Porphyromonas gingivalis enzymology
- 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., (© 2015 by The American Society for Biochemistry and Molecular Biology, Inc.)
- Published
- 2015
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