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Localization of peptidases in lactococci
P S Tan1, M P Chapot-Chartier, K M Pos
1Department of Microbiology, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands, and Station de Recherches Laitieres, Institute National de la Recherche Agronomique, 78350 Jouy-en-Josas, and Laboratoire de Génie des Procédés Biotechnologiques Agro-alimentaires, Institute National de la Recherche Agronomique, 7850 Thiverval-Grignon, France.
Applied and Environmental Microbiology
|January 1, 1992
Summary
Researchers studied the location of five peptidases in Lactococcus lactis. Three peptidases, including X-prolyl-dipeptidyl aminopeptidase, were found in the cell membrane, while others were intracellular.
Area of Science:
- Microbiology
- Enzymology
- Cell Biology
Background:
- Lactococcus lactis is a key bacterium in dairy fermentation.
- Understanding the localization of peptidases is crucial for its industrial applications.
- Previous studies have not fully elucidated the precise location of all peptidases within Lactococcus lactis.
Purpose of the Study:
- To determine the intracellular or extracellular localization of five key peptidases in Lactococcus lactis.
- To differentiate the localization of X-prolyl-dipeptidyl aminopeptidase, endopeptidase, and tripeptidase from other aminopeptidases.
Main Methods:
- Purification of five peptidases from Lactococcus lactis.
- Development of specific polyclonal antibodies for each purified peptidase.
- Cell fractionation followed by immunoblotting.
- Immunogold labeling combined with electron microscopy.
- Analysis of cell membrane fractions.
Main Results:
- All five studied peptidases were confirmed to be intracellular.
- Immunogold labeling revealed a peripheral localization for X-prolyl-dipeptidyl aminopeptidase, endopeptidase, and tripeptidase.
- These three peptidases were detected in cell membrane fractions, while the other two aminopeptidases were not.
Conclusions:
- X-prolyl-dipeptidyl aminopeptidase, endopeptidase, and tripeptidase are associated with the cell periphery/membrane in Lactococcus lactis.
- The two other aminopeptidases are located deeper within the cytoplasm.
- This differential localization has implications for understanding enzyme function and accessibility in Lactococcus lactis.