Related Experiment Videos
Isolation of a membrane-associated Bacteroides gingivalis glycylprolyl protease
1Department of Microbiology, University of British Columbia, Vancouver, Canada.
Abstract:
A low-molecular-weight proteolytic enzyme was purified 47-fold from outer membranes of Bacteroides gingivalis ATCC 33277 by preparative polyacrylamide gel electrophoresis. The enzyme was present in all B. gingivalis strains tested but was not found in other species of black-pigmented Bacteroides. The molecular weight, determined by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis, was 19,500 when the enzyme was heated to 100 degrees C in SDS before electrophoresis and 29,000 when it was mixed with SDS but not heated. The optimum pH, with azocasein as the substrate, was between 6.0 and 6.5. The activity was inhibited by phenylmethylsulfonyl fluoride, N-alpha-p-tosyl-L-lysine chloromethyl ketone, Hg2+, and various reducing agents. The enzyme was active against azocasein, azocoll, proline-rich protein from saliva, and the synthetic peptide glycyl-L-proline-p-nitroanilide. The enzyme did not degrade acid-soluble collagen nor did it hydrolyze various arginine- and lysine-containing synthetic substrates.
Insights
Researchers purified a novel low-molecular-weight proteolytic enzyme from Bacteroides gingivalis outer membranes. This enzyme specifically degrades proline-rich proteins, offering insights into periodontal disease mechanisms.
Area of Science:
- Microbiology
- Enzymology
- Periodontal Pathogenesis
Background:
- Bacteroides gingivalis is a key pathogen in adult periodontitis.
- Outer membrane proteins of B. gingivalis play crucial roles in virulence.
- Proteolytic enzymes are implicated in the tissue destruction associated with periodontitis.
Purpose of the Study:
- To purify and characterize a low-molecular-weight proteolytic enzyme from the outer membranes of Bacteroides gingivalis.
- To determine the substrate specificity and optimal conditions for the enzyme's activity.
- To investigate the enzyme's presence in different B. gingivalis strains.
Main Methods:
- Purification of the enzyme using preparative polyacrylamide gel electrophoresis.
- Determination of molecular weight via sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis under reducing and non-reducing conditions.
- Enzyme activity assays using various substrates including azocasein, azocoll, proline-rich protein, and synthetic peptides.
- pH optimum determination and inhibitor studies.
Main Results:
- A 47-fold purification of a low-molecular-weight proteolytic enzyme from B. gingivalis outer membranes was achieved.
- The enzyme exhibited molecular weights of 19,500 (heated) and 29,000 (unheated) in SDS-PAGE.
- Optimal activity was observed at pH 6.0-6.5, with inhibition by PMSF, TLCK, Hg2+, and reducing agents.
- The enzyme effectively degraded azocasein, azocoll, proline-rich protein, and Gly-Pro-pNA, but not collagen or arginine/lysine substrates.
- The enzyme was detected in all tested B. gingivalis strains but not in other black-pigmented Bacteroides species.
Conclusions:
- A unique low-molecular-weight proteolytic enzyme is associated with the outer membranes of Bacteroides gingivalis.
- The enzyme's substrate specificity suggests a role in the degradation of salivary proline-rich proteins, potentially contributing to virulence.
- Further characterization of this enzyme may provide therapeutic targets for periodontal disease.