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Updated: Jul 12, 2026
10:12
Protein Misfolding Cyclic Amplification of Prions
Published on: November 7, 2012
Lactococcal proteinase maturation protein PrtM is a lipoprotein
A J Haandrikman1, J Kok, G Venema
1Department of Genetics, University of Groningen, Haren, The Netherlands.
Journal of Bacteriology
|July 1, 1991
Summary
Lactococcal proteinase maturation factor PrtM is a membrane-associated lipoprotein essential for proteinase activity. Site-directed mutagenesis revealed its localization and confirmed its role in proteinase production.
Area of Science:
- Microbiology
- Molecular Biology
- Biochemistry
Background:
- Enzymatically active proteinase production in lactococci depends on the proteinase gene (prtP) and a maturation protein gene (prtM).
- Understanding the localization and function of PrtM is crucial for optimizing proteinase activity in lactococcal systems.
Purpose of the Study:
- To characterize the PrtM protein, specifically its cellular localization and post-translational modifications.
- To investigate the role of PrtM in the production of active proteinase in Lactococcus lactis.
Main Methods:
- Expression of the prtM gene in Escherichia coli and purification of the resulting 32-kDa protein.
- Generation of PrtM-specific antibodies for immunogold labeling and Western blot analysis.
- Radiolabeling with [3H]palmitic acid to identify lipid modification.
- Site-directed mutagenesis to replace Cys-24 with Ala and analysis of PrtM secretion and proteinase activity.
Main Results:
- PrtM was identified as a membrane-associated protein in Lactococcus lactis, localized to the cell envelope.
- Radiolabeling confirmed that PrtM is a lipoprotein, indicating lipid modification.
- Mutating the lipid modification site (Cys-24 to Ala) resulted in partial secretion of PrtM without affecting proteinase activity.
Conclusions:
- PrtM is a membrane-associated lipoprotein crucial for the maturation and activity of lactococcal proteinase.
- The lipid modification of PrtM is essential for its proper membrane association and likely its function in proteinase production.
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